LCOV - code coverage report
Current view: top level - src/backend/access/nbtree - nbtutils.c (source / functions) Hit Total Coverage
Test: PostgreSQL 18devel Lines: 855 952 89.8 %
Date: 2025-04-22 08:15:34 Functions: 37 39 94.9 %
Legend: Lines: hit not hit

          Line data    Source code
       1             : /*-------------------------------------------------------------------------
       2             :  *
       3             :  * nbtutils.c
       4             :  *    Utility code for Postgres btree implementation.
       5             :  *
       6             :  * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
       7             :  * Portions Copyright (c) 1994, Regents of the University of California
       8             :  *
       9             :  *
      10             :  * IDENTIFICATION
      11             :  *    src/backend/access/nbtree/nbtutils.c
      12             :  *
      13             :  *-------------------------------------------------------------------------
      14             :  */
      15             : 
      16             : #include "postgres.h"
      17             : 
      18             : #include <time.h>
      19             : 
      20             : #include "access/nbtree.h"
      21             : #include "access/reloptions.h"
      22             : #include "commands/progress.h"
      23             : #include "miscadmin.h"
      24             : #include "utils/datum.h"
      25             : #include "utils/lsyscache.h"
      26             : 
      27             : #define LOOK_AHEAD_REQUIRED_RECHECKS    3
      28             : #define LOOK_AHEAD_DEFAULT_DISTANCE     5
      29             : #define NSKIPADVANCES_THRESHOLD         3
      30             : 
      31             : static inline int32 _bt_compare_array_skey(FmgrInfo *orderproc,
      32             :                                            Datum tupdatum, bool tupnull,
      33             :                                            Datum arrdatum, ScanKey cur);
      34             : static void _bt_binsrch_skiparray_skey(bool cur_elem_trig, ScanDirection dir,
      35             :                                        Datum tupdatum, bool tupnull,
      36             :                                        BTArrayKeyInfo *array, ScanKey cur,
      37             :                                        int32 *set_elem_result);
      38             : static void _bt_skiparray_set_element(Relation rel, ScanKey skey, BTArrayKeyInfo *array,
      39             :                                       int32 set_elem_result, Datum tupdatum, bool tupnull);
      40             : static void _bt_skiparray_set_isnull(Relation rel, ScanKey skey, BTArrayKeyInfo *array);
      41             : static void _bt_array_set_low_or_high(Relation rel, ScanKey skey,
      42             :                                       BTArrayKeyInfo *array, bool low_not_high);
      43             : static bool _bt_array_decrement(Relation rel, ScanKey skey, BTArrayKeyInfo *array);
      44             : static bool _bt_array_increment(Relation rel, ScanKey skey, BTArrayKeyInfo *array);
      45             : static bool _bt_advance_array_keys_increment(IndexScanDesc scan, ScanDirection dir,
      46             :                                              bool *skip_array_set);
      47             : static void _bt_rewind_nonrequired_arrays(IndexScanDesc scan, ScanDirection dir);
      48             : static bool _bt_tuple_before_array_skeys(IndexScanDesc scan, ScanDirection dir,
      49             :                                          IndexTuple tuple, TupleDesc tupdesc, int tupnatts,
      50             :                                          bool readpagetup, int sktrig, bool *scanBehind);
      51             : static bool _bt_advance_array_keys(IndexScanDesc scan, BTReadPageState *pstate,
      52             :                                    IndexTuple tuple, int tupnatts, TupleDesc tupdesc,
      53             :                                    int sktrig, bool sktrig_required);
      54             : #ifdef USE_ASSERT_CHECKING
      55             : static bool _bt_verify_arrays_bt_first(IndexScanDesc scan, ScanDirection dir);
      56             : static bool _bt_verify_keys_with_arraykeys(IndexScanDesc scan);
      57             : #endif
      58             : static bool _bt_oppodir_checkkeys(IndexScanDesc scan, ScanDirection dir,
      59             :                                   IndexTuple finaltup);
      60             : static bool _bt_check_compare(IndexScanDesc scan, ScanDirection dir,
      61             :                               IndexTuple tuple, int tupnatts, TupleDesc tupdesc,
      62             :                               bool advancenonrequired, bool forcenonrequired,
      63             :                               bool *continuescan, int *ikey);
      64             : static bool _bt_check_rowcompare(ScanKey skey,
      65             :                                  IndexTuple tuple, int tupnatts, TupleDesc tupdesc,
      66             :                                  ScanDirection dir, bool forcenonrequired, bool *continuescan);
      67             : static void _bt_checkkeys_look_ahead(IndexScanDesc scan, BTReadPageState *pstate,
      68             :                                      int tupnatts, TupleDesc tupdesc);
      69             : static int  _bt_keep_natts(Relation rel, IndexTuple lastleft,
      70             :                            IndexTuple firstright, BTScanInsert itup_key);
      71             : 
      72             : 
      73             : /*
      74             :  * _bt_mkscankey
      75             :  *      Build an insertion scan key that contains comparison data from itup
      76             :  *      as well as comparator routines appropriate to the key datatypes.
      77             :  *
      78             :  *      The result is intended for use with _bt_compare() and _bt_truncate().
      79             :  *      Callers that don't need to fill out the insertion scankey arguments
      80             :  *      (e.g. they use an ad-hoc comparison routine, or only need a scankey
      81             :  *      for _bt_truncate()) can pass a NULL index tuple.  The scankey will
      82             :  *      be initialized as if an "all truncated" pivot tuple was passed
      83             :  *      instead.
      84             :  *
      85             :  *      Note that we may occasionally have to share lock the metapage to
      86             :  *      determine whether or not the keys in the index are expected to be
      87             :  *      unique (i.e. if this is a "heapkeyspace" index).  We assume a
      88             :  *      heapkeyspace index when caller passes a NULL tuple, allowing index
      89             :  *      build callers to avoid accessing the non-existent metapage.  We
      90             :  *      also assume that the index is _not_ allequalimage when a NULL tuple
      91             :  *      is passed; CREATE INDEX callers call _bt_allequalimage() to set the
      92             :  *      field themselves.
      93             :  */
      94             : BTScanInsert
      95    11817834 : _bt_mkscankey(Relation rel, IndexTuple itup)
      96             : {
      97             :     BTScanInsert key;
      98             :     ScanKey     skey;
      99             :     TupleDesc   itupdesc;
     100             :     int         indnkeyatts;
     101             :     int16      *indoption;
     102             :     int         tupnatts;
     103             :     int         i;
     104             : 
     105    11817834 :     itupdesc = RelationGetDescr(rel);
     106    11817834 :     indnkeyatts = IndexRelationGetNumberOfKeyAttributes(rel);
     107    11817834 :     indoption = rel->rd_indoption;
     108    11817834 :     tupnatts = itup ? BTreeTupleGetNAtts(itup, rel) : 0;
     109             : 
     110             :     Assert(tupnatts <= IndexRelationGetNumberOfAttributes(rel));
     111             : 
     112             :     /*
     113             :      * We'll execute search using scan key constructed on key columns.
     114             :      * Truncated attributes and non-key attributes are omitted from the final
     115             :      * scan key.
     116             :      */
     117    11817834 :     key = palloc(offsetof(BTScanInsertData, scankeys) +
     118    11817834 :                  sizeof(ScanKeyData) * indnkeyatts);
     119    11817834 :     if (itup)
     120    11673000 :         _bt_metaversion(rel, &key->heapkeyspace, &key->allequalimage);
     121             :     else
     122             :     {
     123             :         /* Utility statement callers can set these fields themselves */
     124      144834 :         key->heapkeyspace = true;
     125      144834 :         key->allequalimage = false;
     126             :     }
     127    11817834 :     key->anynullkeys = false;    /* initial assumption */
     128    11817834 :     key->nextkey = false;        /* usual case, required by btinsert */
     129    11817834 :     key->backward = false;       /* usual case, required by btinsert */
     130    11817834 :     key->keysz = Min(indnkeyatts, tupnatts);
     131    11817834 :     key->scantid = key->heapkeyspace && itup ?
     132    23635668 :         BTreeTupleGetHeapTID(itup) : NULL;
     133    11817834 :     skey = key->scankeys;
     134    31949802 :     for (i = 0; i < indnkeyatts; i++)
     135             :     {
     136             :         FmgrInfo   *procinfo;
     137             :         Datum       arg;
     138             :         bool        null;
     139             :         int         flags;
     140             : 
     141             :         /*
     142             :          * We can use the cached (default) support procs since no cross-type
     143             :          * comparison can be needed.
     144             :          */
     145    20131968 :         procinfo = index_getprocinfo(rel, i + 1, BTORDER_PROC);
     146             : 
     147             :         /*
     148             :          * Key arguments built from truncated attributes (or when caller
     149             :          * provides no tuple) are defensively represented as NULL values. They
     150             :          * should never be used.
     151             :          */
     152    20131968 :         if (i < tupnatts)
     153    19872556 :             arg = index_getattr(itup, i + 1, itupdesc, &null);
     154             :         else
     155             :         {
     156      259412 :             arg = (Datum) 0;
     157      259412 :             null = true;
     158             :         }
     159    20131968 :         flags = (null ? SK_ISNULL : 0) | (indoption[i] << SK_BT_INDOPTION_SHIFT);
     160    20131968 :         ScanKeyEntryInitializeWithInfo(&skey[i],
     161             :                                        flags,
     162    20131968 :                                        (AttrNumber) (i + 1),
     163             :                                        InvalidStrategy,
     164             :                                        InvalidOid,
     165    20131968 :                                        rel->rd_indcollation[i],
     166             :                                        procinfo,
     167             :                                        arg);
     168             :         /* Record if any key attribute is NULL (or truncated) */
     169    20131968 :         if (null)
     170      280060 :             key->anynullkeys = true;
     171             :     }
     172             : 
     173             :     /*
     174             :      * In NULLS NOT DISTINCT mode, we pretend that there are no null keys, so
     175             :      * that full uniqueness check is done.
     176             :      */
     177    11817834 :     if (rel->rd_index->indnullsnotdistinct)
     178         186 :         key->anynullkeys = false;
     179             : 
     180    11817834 :     return key;
     181             : }
     182             : 
     183             : /*
     184             :  * free a retracement stack made by _bt_search.
     185             :  */
     186             : void
     187    21982436 : _bt_freestack(BTStack stack)
     188             : {
     189             :     BTStack     ostack;
     190             : 
     191    40348214 :     while (stack != NULL)
     192             :     {
     193    18365778 :         ostack = stack;
     194    18365778 :         stack = stack->bts_parent;
     195    18365778 :         pfree(ostack);
     196             :     }
     197    21982436 : }
     198             : 
     199             : /*
     200             :  * _bt_compare_array_skey() -- apply array comparison function
     201             :  *
     202             :  * Compares caller's tuple attribute value to a scan key/array element.
     203             :  * Helper function used during binary searches of SK_SEARCHARRAY arrays.
     204             :  *
     205             :  *      This routine returns:
     206             :  *          <0 if tupdatum < arrdatum;
     207             :  *           0 if tupdatum == arrdatum;
     208             :  *          >0 if tupdatum > arrdatum.
     209             :  *
     210             :  * This is essentially the same interface as _bt_compare: both functions
     211             :  * compare the value that they're searching for to a binary search pivot.
     212             :  * However, unlike _bt_compare, this function's "tuple argument" comes first,
     213             :  * while its "array/scankey argument" comes second.
     214             : */
     215             : static inline int32
     216      512298 : _bt_compare_array_skey(FmgrInfo *orderproc,
     217             :                        Datum tupdatum, bool tupnull,
     218             :                        Datum arrdatum, ScanKey cur)
     219             : {
     220      512298 :     int32       result = 0;
     221             : 
     222             :     Assert(cur->sk_strategy == BTEqualStrategyNumber);
     223             :     Assert(!(cur->sk_flags & (SK_BT_MINVAL | SK_BT_MAXVAL)));
     224             : 
     225      512298 :     if (tupnull)                /* NULL tupdatum */
     226             :     {
     227         228 :         if (cur->sk_flags & SK_ISNULL)
     228         132 :             result = 0;         /* NULL "=" NULL */
     229          96 :         else if (cur->sk_flags & SK_BT_NULLS_FIRST)
     230           0 :             result = -1;        /* NULL "<" NOT_NULL */
     231             :         else
     232          96 :             result = 1;         /* NULL ">" NOT_NULL */
     233             :     }
     234      512070 :     else if (cur->sk_flags & SK_ISNULL) /* NOT_NULL tupdatum, NULL arrdatum */
     235             :     {
     236       30492 :         if (cur->sk_flags & SK_BT_NULLS_FIRST)
     237          12 :             result = 1;         /* NOT_NULL ">" NULL */
     238             :         else
     239       30480 :             result = -1;        /* NOT_NULL "<" NULL */
     240             :     }
     241             :     else
     242             :     {
     243             :         /*
     244             :          * Like _bt_compare, we need to be careful of cross-type comparisons,
     245             :          * so the left value has to be the value that came from an index tuple
     246             :          */
     247      481578 :         result = DatumGetInt32(FunctionCall2Coll(orderproc, cur->sk_collation,
     248             :                                                  tupdatum, arrdatum));
     249             : 
     250             :         /*
     251             :          * We flip the sign by following the obvious rule: flip whenever the
     252             :          * column is a DESC column.
     253             :          *
     254             :          * _bt_compare does it the wrong way around (flip when *ASC*) in order
     255             :          * to compensate for passing its orderproc arguments backwards.  We
     256             :          * don't need to play these games because we find it natural to pass
     257             :          * tupdatum as the left value (and arrdatum as the right value).
     258             :          */
     259      481578 :         if (cur->sk_flags & SK_BT_DESC)
     260       45552 :             INVERT_COMPARE_RESULT(result);
     261             :     }
     262             : 
     263      512298 :     return result;
     264             : }
     265             : 
     266             : /*
     267             :  * _bt_binsrch_array_skey() -- Binary search for next matching array key
     268             :  *
     269             :  * Returns an index to the first array element >= caller's tupdatum argument.
     270             :  * This convention is more natural for forwards scan callers, but that can't
     271             :  * really matter to backwards scan callers.  Both callers require handling for
     272             :  * the case where the match we return is < tupdatum, and symmetric handling
     273             :  * for the case where our best match is > tupdatum.
     274             :  *
     275             :  * Also sets *set_elem_result to the result _bt_compare_array_skey returned
     276             :  * when we used it to compare the matching array element to tupdatum/tupnull.
     277             :  *
     278             :  * cur_elem_trig indicates if array advancement was triggered by this array's
     279             :  * scan key, and that the array is for a required scan key.  We can apply this
     280             :  * information to find the next matching array element in the current scan
     281             :  * direction using far fewer comparisons (fewer on average, compared to naive
     282             :  * binary search).  This scheme takes advantage of an important property of
     283             :  * required arrays: required arrays always advance in lockstep with the index
     284             :  * scan's progress through the index's key space.
     285             :  */
     286             : int
     287       41654 : _bt_binsrch_array_skey(FmgrInfo *orderproc,
     288             :                        bool cur_elem_trig, ScanDirection dir,
     289             :                        Datum tupdatum, bool tupnull,
     290             :                        BTArrayKeyInfo *array, ScanKey cur,
     291             :                        int32 *set_elem_result)
     292             : {
     293       41654 :     int         low_elem = 0,
     294       41654 :                 mid_elem = -1,
     295       41654 :                 high_elem = array->num_elems - 1,
     296       41654 :                 result = 0;
     297             :     Datum       arrdatum;
     298             : 
     299             :     Assert(cur->sk_flags & SK_SEARCHARRAY);
     300             :     Assert(!(cur->sk_flags & SK_BT_SKIP));
     301             :     Assert(!(cur->sk_flags & SK_ISNULL));    /* SAOP arrays never have NULLs */
     302             :     Assert(cur->sk_strategy == BTEqualStrategyNumber);
     303             : 
     304       41654 :     if (cur_elem_trig)
     305             :     {
     306             :         Assert(!ScanDirectionIsNoMovement(dir));
     307             :         Assert(cur->sk_flags & SK_BT_REQFWD);
     308             : 
     309             :         /*
     310             :          * When the scan key that triggered array advancement is a required
     311             :          * array scan key, it is now certain that the current array element
     312             :          * (plus all prior elements relative to the current scan direction)
     313             :          * cannot possibly be at or ahead of the corresponding tuple value.
     314             :          * (_bt_checkkeys must have called _bt_tuple_before_array_skeys, which
     315             :          * makes sure this is true as a condition of advancing the arrays.)
     316             :          *
     317             :          * This makes it safe to exclude array elements up to and including
     318             :          * the former-current array element from our search.
     319             :          *
     320             :          * Separately, when array advancement was triggered by a required scan
     321             :          * key, the array element immediately after the former-current element
     322             :          * is often either an exact tupdatum match, or a "close by" near-match
     323             :          * (a near-match tupdatum is one whose key space falls _between_ the
     324             :          * former-current and new-current array elements).  We'll detect both
     325             :          * cases via an optimistic comparison of the new search lower bound
     326             :          * (or new search upper bound in the case of backwards scans).
     327             :          */
     328       41336 :         if (ScanDirectionIsForward(dir))
     329             :         {
     330       41276 :             low_elem = array->cur_elem + 1; /* old cur_elem exhausted */
     331             : 
     332             :             /* Compare prospective new cur_elem (also the new lower bound) */
     333       41276 :             if (high_elem >= low_elem)
     334             :             {
     335       33222 :                 arrdatum = array->elem_values[low_elem];
     336       33222 :                 result = _bt_compare_array_skey(orderproc, tupdatum, tupnull,
     337             :                                                 arrdatum, cur);
     338             : 
     339       33222 :                 if (result <= 0)
     340             :                 {
     341             :                     /* Optimistic comparison optimization worked out */
     342       33136 :                     *set_elem_result = result;
     343       33136 :                     return low_elem;
     344             :                 }
     345          86 :                 mid_elem = low_elem;
     346          86 :                 low_elem++;     /* this cur_elem exhausted, too */
     347             :             }
     348             : 
     349        8140 :             if (high_elem < low_elem)
     350             :             {
     351             :                 /* Caller needs to perform "beyond end" array advancement */
     352        8060 :                 *set_elem_result = 1;
     353        8060 :                 return high_elem;
     354             :             }
     355             :         }
     356             :         else
     357             :         {
     358          60 :             high_elem = array->cur_elem - 1; /* old cur_elem exhausted */
     359             : 
     360             :             /* Compare prospective new cur_elem (also the new upper bound) */
     361          60 :             if (high_elem >= low_elem)
     362             :             {
     363          42 :                 arrdatum = array->elem_values[high_elem];
     364          42 :                 result = _bt_compare_array_skey(orderproc, tupdatum, tupnull,
     365             :                                                 arrdatum, cur);
     366             : 
     367          42 :                 if (result >= 0)
     368             :                 {
     369             :                     /* Optimistic comparison optimization worked out */
     370          30 :                     *set_elem_result = result;
     371          30 :                     return high_elem;
     372             :                 }
     373          12 :                 mid_elem = high_elem;
     374          12 :                 high_elem--;    /* this cur_elem exhausted, too */
     375             :             }
     376             : 
     377          30 :             if (high_elem < low_elem)
     378             :             {
     379             :                 /* Caller needs to perform "beyond end" array advancement */
     380          30 :                 *set_elem_result = -1;
     381          30 :                 return low_elem;
     382             :             }
     383             :         }
     384             :     }
     385             : 
     386         698 :     while (high_elem > low_elem)
     387             :     {
     388         438 :         mid_elem = low_elem + ((high_elem - low_elem) / 2);
     389         438 :         arrdatum = array->elem_values[mid_elem];
     390             : 
     391         438 :         result = _bt_compare_array_skey(orderproc, tupdatum, tupnull,
     392             :                                         arrdatum, cur);
     393             : 
     394         438 :         if (result == 0)
     395             :         {
     396             :             /*
     397             :              * It's safe to quit as soon as we see an equal array element.
     398             :              * This often saves an extra comparison or two...
     399             :              */
     400         138 :             low_elem = mid_elem;
     401         138 :             break;
     402             :         }
     403             : 
     404         300 :         if (result > 0)
     405         270 :             low_elem = mid_elem + 1;
     406             :         else
     407          30 :             high_elem = mid_elem;
     408             :     }
     409             : 
     410             :     /*
     411             :      * ...but our caller also cares about how its searched-for tuple datum
     412             :      * compares to the low_elem datum.  Must always set *set_elem_result with
     413             :      * the result of that comparison specifically.
     414             :      */
     415         398 :     if (low_elem != mid_elem)
     416         242 :         result = _bt_compare_array_skey(orderproc, tupdatum, tupnull,
     417         242 :                                         array->elem_values[low_elem], cur);
     418             : 
     419         398 :     *set_elem_result = result;
     420             : 
     421         398 :     return low_elem;
     422             : }
     423             : 
     424             : /*
     425             :  * _bt_binsrch_skiparray_skey() -- "Binary search" within a skip array
     426             :  *
     427             :  * Does not return an index into the array, since skip arrays don't really
     428             :  * contain elements (they generate their array elements procedurally instead).
     429             :  * Our interface matches that of _bt_binsrch_array_skey in every other way.
     430             :  *
     431             :  * Sets *set_elem_result just like _bt_binsrch_array_skey would with a true
     432             :  * array.  The value 0 indicates that tupdatum/tupnull is within the range of
     433             :  * the skip array.  We return -1 when tupdatum/tupnull is lower that any value
     434             :  * within the range of the array, and 1 when it is higher than every value.
     435             :  * Caller should pass *set_elem_result to _bt_skiparray_set_element to advance
     436             :  * the array.
     437             :  *
     438             :  * cur_elem_trig indicates if array advancement was triggered by this array's
     439             :  * scan key.  We use this to optimize-away comparisons that are known by our
     440             :  * caller to be unnecessary from context, just like _bt_binsrch_array_skey.
     441             :  */
     442             : static void
     443      165498 : _bt_binsrch_skiparray_skey(bool cur_elem_trig, ScanDirection dir,
     444             :                            Datum tupdatum, bool tupnull,
     445             :                            BTArrayKeyInfo *array, ScanKey cur,
     446             :                            int32 *set_elem_result)
     447             : {
     448             :     Assert(cur->sk_flags & SK_BT_SKIP);
     449             :     Assert(cur->sk_flags & SK_SEARCHARRAY);
     450             :     Assert(cur->sk_flags & SK_BT_REQFWD);
     451             :     Assert(array->num_elems == -1);
     452             :     Assert(!ScanDirectionIsNoMovement(dir));
     453             : 
     454      165498 :     if (array->null_elem)
     455             :     {
     456             :         Assert(!array->low_compare && !array->high_compare);
     457             : 
     458      141410 :         *set_elem_result = 0;
     459      141410 :         return;
     460             :     }
     461             : 
     462       24088 :     if (tupnull)                /* NULL tupdatum */
     463             :     {
     464          24 :         if (cur->sk_flags & SK_BT_NULLS_FIRST)
     465           0 :             *set_elem_result = -1;  /* NULL "<" NOT_NULL */
     466             :         else
     467          24 :             *set_elem_result = 1;   /* NULL ">" NOT_NULL */
     468          24 :         return;
     469             :     }
     470             : 
     471             :     /*
     472             :      * Array inequalities determine whether tupdatum is within the range of
     473             :      * caller's skip array
     474             :      */
     475       24064 :     *set_elem_result = 0;
     476       24064 :     if (ScanDirectionIsForward(dir))
     477             :     {
     478             :         /*
     479             :          * Evaluate low_compare first (unless cur_elem_trig tells us that it
     480             :          * cannot possibly fail to be satisfied), then evaluate high_compare
     481             :          */
     482       24016 :         if (!cur_elem_trig && array->low_compare &&
     483         458 :             !DatumGetBool(FunctionCall2Coll(&array->low_compare->sk_func,
     484         458 :                                             array->low_compare->sk_collation,
     485             :                                             tupdatum,
     486         458 :                                             array->low_compare->sk_argument)))
     487           0 :             *set_elem_result = -1;
     488       24016 :         else if (array->high_compare &&
     489        8104 :                  !DatumGetBool(FunctionCall2Coll(&array->high_compare->sk_func,
     490        8104 :                                                  array->high_compare->sk_collation,
     491             :                                                  tupdatum,
     492        8104 :                                                  array->high_compare->sk_argument)))
     493        6400 :             *set_elem_result = 1;
     494             :     }
     495             :     else
     496             :     {
     497             :         /*
     498             :          * Evaluate high_compare first (unless cur_elem_trig tells us that it
     499             :          * cannot possibly fail to be satisfied), then evaluate low_compare
     500             :          */
     501          48 :         if (!cur_elem_trig && array->high_compare &&
     502           6 :             !DatumGetBool(FunctionCall2Coll(&array->high_compare->sk_func,
     503           6 :                                             array->high_compare->sk_collation,
     504             :                                             tupdatum,
     505           6 :                                             array->high_compare->sk_argument)))
     506           0 :             *set_elem_result = 1;
     507          48 :         else if (array->low_compare &&
     508          24 :                  !DatumGetBool(FunctionCall2Coll(&array->low_compare->sk_func,
     509          24 :                                                  array->low_compare->sk_collation,
     510             :                                                  tupdatum,
     511          24 :                                                  array->low_compare->sk_argument)))
     512           0 :             *set_elem_result = -1;
     513             :     }
     514             : 
     515             :     /*
     516             :      * Assert that any keys that were assumed to be satisfied already (due to
     517             :      * caller passing cur_elem_trig=true) really are satisfied as expected
     518             :      */
     519             : #ifdef USE_ASSERT_CHECKING
     520             :     if (cur_elem_trig)
     521             :     {
     522             :         if (ScanDirectionIsForward(dir) && array->low_compare)
     523             :             Assert(DatumGetBool(FunctionCall2Coll(&array->low_compare->sk_func,
     524             :                                                   array->low_compare->sk_collation,
     525             :                                                   tupdatum,
     526             :                                                   array->low_compare->sk_argument)));
     527             : 
     528             :         if (ScanDirectionIsBackward(dir) && array->high_compare)
     529             :             Assert(DatumGetBool(FunctionCall2Coll(&array->high_compare->sk_func,
     530             :                                                   array->high_compare->sk_collation,
     531             :                                                   tupdatum,
     532             :                                                   array->high_compare->sk_argument)));
     533             :     }
     534             : #endif
     535             : }
     536             : 
     537             : /*
     538             :  * _bt_skiparray_set_element() -- Set skip array scan key's sk_argument
     539             :  *
     540             :  * Caller passes set_elem_result returned by _bt_binsrch_skiparray_skey for
     541             :  * caller's tupdatum/tupnull.
     542             :  *
     543             :  * We copy tupdatum/tupnull into skey's sk_argument iff set_elem_result == 0.
     544             :  * Otherwise, we set skey to either the lowest or highest value that's within
     545             :  * the range of caller's skip array (whichever is the best available match to
     546             :  * tupdatum/tupnull that is still within the range of the skip array according
     547             :  * to _bt_binsrch_skiparray_skey/set_elem_result).
     548             :  */
     549             : static void
     550      155944 : _bt_skiparray_set_element(Relation rel, ScanKey skey, BTArrayKeyInfo *array,
     551             :                           int32 set_elem_result, Datum tupdatum, bool tupnull)
     552             : {
     553             :     Assert(skey->sk_flags & SK_BT_SKIP);
     554             :     Assert(skey->sk_flags & SK_SEARCHARRAY);
     555             : 
     556      155944 :     if (set_elem_result)
     557             :     {
     558             :         /* tupdatum/tupnull is out of the range of the skip array */
     559             :         Assert(!array->null_elem);
     560             : 
     561         640 :         _bt_array_set_low_or_high(rel, skey, array, set_elem_result < 0);
     562         640 :         return;
     563             :     }
     564             : 
     565             :     /* Advance skip array to tupdatum (or tupnull) value */
     566      155304 :     if (unlikely(tupnull))
     567             :     {
     568          36 :         _bt_skiparray_set_isnull(rel, skey, array);
     569          36 :         return;
     570             :     }
     571             : 
     572             :     /* Free memory previously allocated for sk_argument if needed */
     573      155268 :     if (!array->attbyval && skey->sk_argument)
     574       80496 :         pfree(DatumGetPointer(skey->sk_argument));
     575             : 
     576             :     /* tupdatum becomes new sk_argument/new current element */
     577      155268 :     skey->sk_flags &= ~(SK_SEARCHNULL | SK_ISNULL |
     578             :                         SK_BT_MINVAL | SK_BT_MAXVAL |
     579             :                         SK_BT_NEXT | SK_BT_PRIOR);
     580      155268 :     skey->sk_argument = datumCopy(tupdatum, array->attbyval, array->attlen);
     581             : }
     582             : 
     583             : /*
     584             :  * _bt_skiparray_set_isnull() -- set skip array scan key to NULL
     585             :  */
     586             : static void
     587          48 : _bt_skiparray_set_isnull(Relation rel, ScanKey skey, BTArrayKeyInfo *array)
     588             : {
     589             :     Assert(skey->sk_flags & SK_BT_SKIP);
     590             :     Assert(skey->sk_flags & SK_SEARCHARRAY);
     591             :     Assert(array->null_elem && !array->low_compare && !array->high_compare);
     592             : 
     593             :     /* Free memory previously allocated for sk_argument if needed */
     594          48 :     if (!array->attbyval && skey->sk_argument)
     595           6 :         pfree(DatumGetPointer(skey->sk_argument));
     596             : 
     597             :     /* NULL becomes new sk_argument/new current element */
     598          48 :     skey->sk_argument = (Datum) 0;
     599          48 :     skey->sk_flags &= ~(SK_BT_MINVAL | SK_BT_MAXVAL |
     600             :                         SK_BT_NEXT | SK_BT_PRIOR);
     601          48 :     skey->sk_flags |= (SK_SEARCHNULL | SK_ISNULL);
     602          48 : }
     603             : 
     604             : /*
     605             :  * _bt_start_array_keys() -- Initialize array keys at start of a scan
     606             :  *
     607             :  * Set up the cur_elem counters and fill in the first sk_argument value for
     608             :  * each array scankey.
     609             :  */
     610             : void
     611       79394 : _bt_start_array_keys(IndexScanDesc scan, ScanDirection dir)
     612             : {
     613       79394 :     Relation    rel = scan->indexRelation;
     614       79394 :     BTScanOpaque so = (BTScanOpaque) scan->opaque;
     615             : 
     616             :     Assert(so->numArrayKeys);
     617             :     Assert(so->qual_ok);
     618             : 
     619      159368 :     for (int i = 0; i < so->numArrayKeys; i++)
     620             :     {
     621       79974 :         BTArrayKeyInfo *array = &so->arrayKeys[i];
     622       79974 :         ScanKey     skey = &so->keyData[array->scan_key];
     623             : 
     624             :         Assert(skey->sk_flags & SK_SEARCHARRAY);
     625             : 
     626       79974 :         _bt_array_set_low_or_high(rel, skey, array,
     627             :                                   ScanDirectionIsForward(dir));
     628             :     }
     629       79394 :     so->scanBehind = so->oppositeDirCheck = false;    /* reset */
     630       79394 : }
     631             : 
     632             : /*
     633             :  * _bt_array_set_low_or_high() -- Set array scan key to lowest/highest element
     634             :  *
     635             :  * Caller also passes associated scan key, which will have its argument set to
     636             :  * the lowest/highest array value in passing.
     637             :  */
     638             : static void
     639       91420 : _bt_array_set_low_or_high(Relation rel, ScanKey skey, BTArrayKeyInfo *array,
     640             :                           bool low_not_high)
     641             : {
     642             :     Assert(skey->sk_flags & SK_SEARCHARRAY);
     643             : 
     644       91420 :     if (array->num_elems != -1)
     645             :     {
     646             :         /* set low or high element for SAOP array */
     647       84636 :         int         set_elem = 0;
     648             : 
     649             :         Assert(!(skey->sk_flags & SK_BT_SKIP));
     650             : 
     651       84636 :         if (!low_not_high)
     652        8292 :             set_elem = array->num_elems - 1;
     653             : 
     654             :         /*
     655             :          * Just copy over array datum (only skip arrays require freeing and
     656             :          * allocating memory for sk_argument)
     657             :          */
     658       84636 :         array->cur_elem = set_elem;
     659       84636 :         skey->sk_argument = array->elem_values[set_elem];
     660             : 
     661       84636 :         return;
     662             :     }
     663             : 
     664             :     /* set low or high element for skip array */
     665             :     Assert(skey->sk_flags & SK_BT_SKIP);
     666             :     Assert(array->num_elems == -1);
     667             : 
     668             :     /* Free memory previously allocated for sk_argument if needed */
     669        6784 :     if (!array->attbyval && skey->sk_argument)
     670         530 :         pfree(DatumGetPointer(skey->sk_argument));
     671             : 
     672             :     /* Reset flags */
     673        6784 :     skey->sk_argument = (Datum) 0;
     674        6784 :     skey->sk_flags &= ~(SK_SEARCHNULL | SK_ISNULL |
     675             :                         SK_BT_MINVAL | SK_BT_MAXVAL |
     676             :                         SK_BT_NEXT | SK_BT_PRIOR);
     677             : 
     678        6784 :     if (array->null_elem &&
     679        5298 :         (low_not_high == ((skey->sk_flags & SK_BT_NULLS_FIRST) != 0)))
     680             :     {
     681             :         /* Requested element (either lowest or highest) has the value NULL */
     682         918 :         skey->sk_flags |= (SK_SEARCHNULL | SK_ISNULL);
     683             :     }
     684        5866 :     else if (low_not_high)
     685             :     {
     686             :         /* Setting array to lowest element (according to low_compare) */
     687        5150 :         skey->sk_flags |= SK_BT_MINVAL;
     688             :     }
     689             :     else
     690             :     {
     691             :         /* Setting array to highest element (according to high_compare) */
     692         716 :         skey->sk_flags |= SK_BT_MAXVAL;
     693             :     }
     694             : }
     695             : 
     696             : /*
     697             :  * _bt_array_decrement() -- decrement array scan key's sk_argument
     698             :  *
     699             :  * Return value indicates whether caller's array was successfully decremented.
     700             :  * Cannot decrement an array whose current element is already the first one.
     701             :  */
     702             : static bool
     703         912 : _bt_array_decrement(Relation rel, ScanKey skey, BTArrayKeyInfo *array)
     704             : {
     705         912 :     bool        uflow = false;
     706             :     Datum       dec_sk_argument;
     707             : 
     708             :     Assert(skey->sk_flags & SK_SEARCHARRAY);
     709             :     Assert(!(skey->sk_flags & (SK_BT_MAXVAL | SK_BT_NEXT | SK_BT_PRIOR)));
     710             : 
     711             :     /* SAOP array? */
     712         912 :     if (array->num_elems != -1)
     713             :     {
     714             :         Assert(!(skey->sk_flags & (SK_BT_SKIP | SK_BT_MINVAL | SK_BT_MAXVAL)));
     715          36 :         if (array->cur_elem > 0)
     716             :         {
     717             :             /*
     718             :              * Just decrement current element, and assign its datum to skey
     719             :              * (only skip arrays need us to free existing sk_argument memory)
     720             :              */
     721           6 :             array->cur_elem--;
     722           6 :             skey->sk_argument = array->elem_values[array->cur_elem];
     723             : 
     724             :             /* Successfully decremented array */
     725           6 :             return true;
     726             :         }
     727             : 
     728             :         /* Cannot decrement to before first array element */
     729          30 :         return false;
     730             :     }
     731             : 
     732             :     /* Nope, this is a skip array */
     733             :     Assert(skey->sk_flags & SK_BT_SKIP);
     734             : 
     735             :     /*
     736             :      * The sentinel value that represents the minimum value within the range
     737             :      * of a skip array (often just -inf) is never decrementable
     738             :      */
     739         876 :     if (skey->sk_flags & SK_BT_MINVAL)
     740           0 :         return false;
     741             : 
     742             :     /*
     743             :      * When the current array element is NULL, and the lowest sorting value in
     744             :      * the index is also NULL, we cannot decrement before first array element
     745             :      */
     746         876 :     if ((skey->sk_flags & SK_ISNULL) && (skey->sk_flags & SK_BT_NULLS_FIRST))
     747           0 :         return false;
     748             : 
     749             :     /*
     750             :      * Opclasses without skip support "decrement" the scan key's current
     751             :      * element by setting the PRIOR flag.  The true prior value is determined
     752             :      * by repositioning to the last index tuple < existing sk_argument/current
     753             :      * array element.  Note that this works in the usual way when the scan key
     754             :      * is already marked ISNULL (i.e. when the current element is NULL).
     755             :      */
     756         876 :     if (!array->sksup)
     757             :     {
     758             :         /* Successfully "decremented" array */
     759          12 :         skey->sk_flags |= SK_BT_PRIOR;
     760          12 :         return true;
     761             :     }
     762             : 
     763             :     /*
     764             :      * Opclasses with skip support directly decrement sk_argument
     765             :      */
     766         864 :     if (skey->sk_flags & SK_ISNULL)
     767             :     {
     768             :         Assert(!(skey->sk_flags & SK_BT_NULLS_FIRST));
     769             : 
     770             :         /*
     771             :          * Existing sk_argument/array element is NULL (for an IS NULL qual).
     772             :          *
     773             :          * "Decrement" from NULL to the high_elem value provided by opclass
     774             :          * skip support routine.
     775             :          */
     776           6 :         skey->sk_flags &= ~(SK_SEARCHNULL | SK_ISNULL);
     777          12 :         skey->sk_argument = datumCopy(array->sksup->high_elem,
     778           6 :                                       array->attbyval, array->attlen);
     779           6 :         return true;
     780             :     }
     781             : 
     782             :     /*
     783             :      * Ask opclass support routine to provide decremented copy of existing
     784             :      * non-NULL sk_argument
     785             :      */
     786         858 :     dec_sk_argument = array->sksup->decrement(rel, skey->sk_argument, &uflow);
     787         858 :     if (unlikely(uflow))
     788             :     {
     789             :         /* dec_sk_argument has undefined value (so no pfree) */
     790           0 :         if (array->null_elem && (skey->sk_flags & SK_BT_NULLS_FIRST))
     791             :         {
     792           0 :             _bt_skiparray_set_isnull(rel, skey, array);
     793             : 
     794             :             /* Successfully "decremented" array to NULL */
     795           0 :             return true;
     796             :         }
     797             : 
     798             :         /* Cannot decrement to before first array element */
     799           0 :         return false;
     800             :     }
     801             : 
     802             :     /*
     803             :      * Successfully decremented sk_argument to a non-NULL value.  Make sure
     804             :      * that the decremented value is still within the range of the array.
     805             :      */
     806         858 :     if (array->low_compare &&
     807          12 :         !DatumGetBool(FunctionCall2Coll(&array->low_compare->sk_func,
     808          12 :                                         array->low_compare->sk_collation,
     809             :                                         dec_sk_argument,
     810          12 :                                         array->low_compare->sk_argument)))
     811             :     {
     812             :         /* Keep existing sk_argument after all */
     813           6 :         if (!array->attbyval)
     814           0 :             pfree(DatumGetPointer(dec_sk_argument));
     815             : 
     816             :         /* Cannot decrement to before first array element */
     817           6 :         return false;
     818             :     }
     819             : 
     820             :     /* Accept value returned by opclass decrement callback */
     821         852 :     if (!array->attbyval && skey->sk_argument)
     822           0 :         pfree(DatumGetPointer(skey->sk_argument));
     823         852 :     skey->sk_argument = dec_sk_argument;
     824             : 
     825             :     /* Successfully decremented array */
     826         852 :     return true;
     827             : }
     828             : 
     829             : /*
     830             :  * _bt_array_increment() -- increment array scan key's sk_argument
     831             :  *
     832             :  * Return value indicates whether caller's array was successfully incremented.
     833             :  * Cannot increment an array whose current element is already the final one.
     834             :  */
     835             : static bool
     836       31402 : _bt_array_increment(Relation rel, ScanKey skey, BTArrayKeyInfo *array)
     837             : {
     838       31402 :     bool        oflow = false;
     839             :     Datum       inc_sk_argument;
     840             : 
     841             :     Assert(skey->sk_flags & SK_SEARCHARRAY);
     842             :     Assert(!(skey->sk_flags & (SK_BT_MINVAL | SK_BT_NEXT | SK_BT_PRIOR)));
     843             : 
     844             :     /* SAOP array? */
     845       31402 :     if (array->num_elems != -1)
     846             :     {
     847             :         Assert(!(skey->sk_flags & (SK_BT_SKIP | SK_BT_MINVAL | SK_BT_MAXVAL)));
     848        8316 :         if (array->cur_elem < array->num_elems - 1)
     849             :         {
     850             :             /*
     851             :              * Just increment current element, and assign its datum to skey
     852             :              * (only skip arrays need us to free existing sk_argument memory)
     853             :              */
     854          38 :             array->cur_elem++;
     855          38 :             skey->sk_argument = array->elem_values[array->cur_elem];
     856             : 
     857             :             /* Successfully incremented array */
     858          38 :             return true;
     859             :         }
     860             : 
     861             :         /* Cannot increment past final array element */
     862        8278 :         return false;
     863             :     }
     864             : 
     865             :     /* Nope, this is a skip array */
     866             :     Assert(skey->sk_flags & SK_BT_SKIP);
     867             : 
     868             :     /*
     869             :      * The sentinel value that represents the maximum value within the range
     870             :      * of a skip array (often just +inf) is never incrementable
     871             :      */
     872       23086 :     if (skey->sk_flags & SK_BT_MAXVAL)
     873         640 :         return false;
     874             : 
     875             :     /*
     876             :      * When the current array element is NULL, and the highest sorting value
     877             :      * in the index is also NULL, we cannot increment past the final element
     878             :      */
     879       22446 :     if ((skey->sk_flags & SK_ISNULL) && !(skey->sk_flags & SK_BT_NULLS_FIRST))
     880         438 :         return false;
     881             : 
     882             :     /*
     883             :      * Opclasses without skip support "increment" the scan key's current
     884             :      * element by setting the NEXT flag.  The true next value is determined by
     885             :      * repositioning to the first index tuple > existing sk_argument/current
     886             :      * array element.  Note that this works in the usual way when the scan key
     887             :      * is already marked ISNULL (i.e. when the current element is NULL).
     888             :      */
     889       22008 :     if (!array->sksup)
     890             :     {
     891             :         /* Successfully "incremented" array */
     892       14724 :         skey->sk_flags |= SK_BT_NEXT;
     893       14724 :         return true;
     894             :     }
     895             : 
     896             :     /*
     897             :      * Opclasses with skip support directly increment sk_argument
     898             :      */
     899        7284 :     if (skey->sk_flags & SK_ISNULL)
     900             :     {
     901             :         Assert(skey->sk_flags & SK_BT_NULLS_FIRST);
     902             : 
     903             :         /*
     904             :          * Existing sk_argument/array element is NULL (for an IS NULL qual).
     905             :          *
     906             :          * "Increment" from NULL to the low_elem value provided by opclass
     907             :          * skip support routine.
     908             :          */
     909          36 :         skey->sk_flags &= ~(SK_SEARCHNULL | SK_ISNULL);
     910          72 :         skey->sk_argument = datumCopy(array->sksup->low_elem,
     911          36 :                                       array->attbyval, array->attlen);
     912          36 :         return true;
     913             :     }
     914             : 
     915             :     /*
     916             :      * Ask opclass support routine to provide incremented copy of existing
     917             :      * non-NULL sk_argument
     918             :      */
     919        7248 :     inc_sk_argument = array->sksup->increment(rel, skey->sk_argument, &oflow);
     920        7248 :     if (unlikely(oflow))
     921             :     {
     922             :         /* inc_sk_argument has undefined value (so no pfree) */
     923          30 :         if (array->null_elem && !(skey->sk_flags & SK_BT_NULLS_FIRST))
     924             :         {
     925          12 :             _bt_skiparray_set_isnull(rel, skey, array);
     926             : 
     927             :             /* Successfully "incremented" array to NULL */
     928          12 :             return true;
     929             :         }
     930             : 
     931             :         /* Cannot increment past final array element */
     932          18 :         return false;
     933             :     }
     934             : 
     935             :     /*
     936             :      * Successfully incremented sk_argument to a non-NULL value.  Make sure
     937             :      * that the incremented value is still within the range of the array.
     938             :      */
     939        7218 :     if (array->high_compare &&
     940          42 :         !DatumGetBool(FunctionCall2Coll(&array->high_compare->sk_func,
     941          42 :                                         array->high_compare->sk_collation,
     942             :                                         inc_sk_argument,
     943          42 :                                         array->high_compare->sk_argument)))
     944             :     {
     945             :         /* Keep existing sk_argument after all */
     946          12 :         if (!array->attbyval)
     947           0 :             pfree(DatumGetPointer(inc_sk_argument));
     948             : 
     949             :         /* Cannot increment past final array element */
     950          12 :         return false;
     951             :     }
     952             : 
     953             :     /* Accept value returned by opclass increment callback */
     954        7206 :     if (!array->attbyval && skey->sk_argument)
     955           0 :         pfree(DatumGetPointer(skey->sk_argument));
     956        7206 :     skey->sk_argument = inc_sk_argument;
     957             : 
     958             :     /* Successfully incremented array */
     959        7206 :     return true;
     960             : }
     961             : 
     962             : /*
     963             :  * _bt_advance_array_keys_increment() -- Advance to next set of array elements
     964             :  *
     965             :  * Advances the array keys by a single increment in the current scan
     966             :  * direction.  When there are multiple array keys this can roll over from the
     967             :  * lowest order array to higher order arrays.
     968             :  *
     969             :  * Returns true if there is another set of values to consider, false if not.
     970             :  * On true result, the scankeys are initialized with the next set of values.
     971             :  * On false result, the scankeys stay the same, and the array keys are not
     972             :  * advanced (every array remains at its final element for scan direction).
     973             :  */
     974             : static bool
     975       31172 : _bt_advance_array_keys_increment(IndexScanDesc scan, ScanDirection dir,
     976             :                                  bool *skip_array_set)
     977             : {
     978       31172 :     Relation    rel = scan->indexRelation;
     979       31172 :     BTScanOpaque so = (BTScanOpaque) scan->opaque;
     980             : 
     981             :     /*
     982             :      * We must advance the last array key most quickly, since it will
     983             :      * correspond to the lowest-order index column among the available
     984             :      * qualifications
     985             :      */
     986       40594 :     for (int i = so->numArrayKeys - 1; i >= 0; i--)
     987             :     {
     988       32314 :         BTArrayKeyInfo *array = &so->arrayKeys[i];
     989       32314 :         ScanKey     skey = &so->keyData[array->scan_key];
     990             : 
     991       32314 :         if (array->num_elems == -1)
     992       23962 :             *skip_array_set = true;
     993             : 
     994       32314 :         if (ScanDirectionIsForward(dir))
     995             :         {
     996       31402 :             if (_bt_array_increment(rel, skey, array))
     997       22016 :                 return true;
     998             :         }
     999             :         else
    1000             :         {
    1001         912 :             if (_bt_array_decrement(rel, skey, array))
    1002         876 :                 return true;
    1003             :         }
    1004             : 
    1005             :         /*
    1006             :          * Couldn't increment (or decrement) array.  Handle array roll over.
    1007             :          *
    1008             :          * Start over at the array's lowest sorting value (or its highest
    1009             :          * value, for backward scans)...
    1010             :          */
    1011        9422 :         _bt_array_set_low_or_high(rel, skey, array,
    1012             :                                   ScanDirectionIsForward(dir));
    1013             : 
    1014             :         /* ...then increment (or decrement) next most significant array */
    1015             :     }
    1016             : 
    1017             :     /*
    1018             :      * The array keys are now exhausted.
    1019             :      *
    1020             :      * Restore the array keys to the state they were in immediately before we
    1021             :      * were called.  This ensures that the arrays only ever ratchet in the
    1022             :      * current scan direction.
    1023             :      *
    1024             :      * Without this, scans could overlook matching tuples when the scan
    1025             :      * direction gets reversed just before btgettuple runs out of items to
    1026             :      * return, but just after _bt_readpage prepares all the items from the
    1027             :      * scan's final page in so->currPos.  When we're on the final page it is
    1028             :      * typical for so->currPos to get invalidated once btgettuple finally
    1029             :      * returns false, which'll effectively invalidate the scan's array keys.
    1030             :      * That hasn't happened yet, though -- and in general it may never happen.
    1031             :      */
    1032        8280 :     _bt_start_array_keys(scan, -dir);
    1033             : 
    1034        8280 :     return false;
    1035             : }
    1036             : 
    1037             : /*
    1038             :  * _bt_rewind_nonrequired_arrays() -- Rewind SAOP arrays not marked required
    1039             :  *
    1040             :  * Called when _bt_advance_array_keys decides to start a new primitive index
    1041             :  * scan on the basis of the current scan position being before the position
    1042             :  * that _bt_first is capable of repositioning the scan to by applying an
    1043             :  * inequality operator required in the opposite-to-scan direction only.
    1044             :  *
    1045             :  * Although equality strategy scan keys (for both arrays and non-arrays alike)
    1046             :  * are either marked required in both directions or in neither direction,
    1047             :  * there is a sense in which non-required arrays behave like required arrays.
    1048             :  * With a qual such as "WHERE a IN (100, 200) AND b >= 3 AND c IN (5, 6, 7)",
    1049             :  * the scan key on "c" is non-required, but nevertheless enables positioning
    1050             :  * the scan at the first tuple >= "(100, 3, 5)" on the leaf level during the
    1051             :  * first descent of the tree by _bt_first.  Later on, there could also be a
    1052             :  * second descent, that places the scan right before tuples >= "(200, 3, 5)".
    1053             :  * _bt_first must never be allowed to build an insertion scan key whose "c"
    1054             :  * entry is set to a value other than 5, the "c" array's first element/value.
    1055             :  * (Actually, it's the first in the current scan direction.  This example uses
    1056             :  * a forward scan.)
    1057             :  *
    1058             :  * Calling here resets the array scan key elements for the scan's non-required
    1059             :  * arrays.  This is strictly necessary for correctness in a subset of cases
    1060             :  * involving "required in opposite direction"-triggered primitive index scans.
    1061             :  * Not all callers are at risk of _bt_first using a non-required array like
    1062             :  * this, but advancement always resets the arrays when another primitive scan
    1063             :  * is scheduled, just to keep things simple.  Array advancement even makes
    1064             :  * sure to reset non-required arrays during scans that have no inequalities.
    1065             :  * (Advancement still won't call here when there are no inequalities, though
    1066             :  * that's just because it's all handled indirectly instead.)
    1067             :  *
    1068             :  * Note: _bt_verify_arrays_bt_first is called by an assertion to enforce that
    1069             :  * everybody got this right.
    1070             :  *
    1071             :  * Note: In practice almost all SAOP arrays are marked required during
    1072             :  * preprocessing (if necessary by generating skip arrays).  It is hardly ever
    1073             :  * truly necessary to call here, but consistently doing so is simpler.
    1074             :  */
    1075             : static void
    1076        3326 : _bt_rewind_nonrequired_arrays(IndexScanDesc scan, ScanDirection dir)
    1077             : {
    1078        3326 :     Relation    rel = scan->indexRelation;
    1079        3326 :     BTScanOpaque so = (BTScanOpaque) scan->opaque;
    1080        3326 :     int         arrayidx = 0;
    1081             : 
    1082        9662 :     for (int ikey = 0; ikey < so->numberOfKeys; ikey++)
    1083             :     {
    1084        6336 :         ScanKey     cur = so->keyData + ikey;
    1085        6336 :         BTArrayKeyInfo *array = NULL;
    1086             : 
    1087        6336 :         if (!(cur->sk_flags & SK_SEARCHARRAY) ||
    1088        3380 :             cur->sk_strategy != BTEqualStrategyNumber)
    1089        2956 :             continue;
    1090             : 
    1091        3380 :         array = &so->arrayKeys[arrayidx++];
    1092             :         Assert(array->scan_key == ikey);
    1093             : 
    1094        3380 :         if ((cur->sk_flags & (SK_BT_REQFWD | SK_BT_REQBKWD)))
    1095        3380 :             continue;
    1096             : 
    1097             :         Assert(array->num_elems != -1); /* No non-required skip arrays */
    1098             : 
    1099           0 :         _bt_array_set_low_or_high(rel, cur, array,
    1100             :                                   ScanDirectionIsForward(dir));
    1101             :     }
    1102        3326 : }
    1103             : 
    1104             : /*
    1105             :  * _bt_tuple_before_array_skeys() -- too early to advance required arrays?
    1106             :  *
    1107             :  * We always compare the tuple using the current array keys (which we assume
    1108             :  * are already set in so->keyData[]).  readpagetup indicates if tuple is the
    1109             :  * scan's current _bt_readpage-wise tuple.
    1110             :  *
    1111             :  * readpagetup callers must only call here when _bt_check_compare already set
    1112             :  * continuescan=false.  We help these callers deal with _bt_check_compare's
    1113             :  * inability to distinguishing between the < and > cases (it uses equality
    1114             :  * operator scan keys, whereas we use 3-way ORDER procs).  These callers pass
    1115             :  * a _bt_check_compare-set sktrig value that indicates which scan key
    1116             :  * triggered the call (!readpagetup callers just pass us sktrig=0 instead).
    1117             :  * This information allows us to avoid wastefully checking earlier scan keys
    1118             :  * that were already deemed to have been satisfied inside _bt_check_compare.
    1119             :  *
    1120             :  * Returns false when caller's tuple is >= the current required equality scan
    1121             :  * keys (or <=, in the case of backwards scans).  This happens to readpagetup
    1122             :  * callers when the scan has reached the point of needing its array keys
    1123             :  * advanced; caller will need to advance required and non-required arrays at
    1124             :  * scan key offsets >= sktrig, plus scan keys < sktrig iff sktrig rolls over.
    1125             :  * (When we return false to readpagetup callers, tuple can only be == current
    1126             :  * required equality scan keys when caller's sktrig indicates that the arrays
    1127             :  * need to be advanced due to an unsatisfied required inequality key trigger.)
    1128             :  *
    1129             :  * Returns true when caller passes a tuple that is < the current set of
    1130             :  * equality keys for the most significant non-equal required scan key/column
    1131             :  * (or > the keys, during backwards scans).  This happens to readpagetup
    1132             :  * callers when tuple is still before the start of matches for the scan's
    1133             :  * required equality strategy scan keys.  (sktrig can't have indicated that an
    1134             :  * inequality strategy scan key wasn't satisfied in _bt_check_compare when we
    1135             :  * return true.  In fact, we automatically return false when passed such an
    1136             :  * inequality sktrig by readpagetup callers -- _bt_check_compare's initial
    1137             :  * continuescan=false doesn't really need to be confirmed here by us.)
    1138             :  *
    1139             :  * !readpagetup callers optionally pass us *scanBehind, which tracks whether
    1140             :  * any missing truncated attributes might have affected array advancement
    1141             :  * (compared to what would happen if it was shown the first non-pivot tuple on
    1142             :  * the page to the right of caller's finaltup/high key tuple instead).  It's
    1143             :  * only possible that we'll set *scanBehind to true when caller passes us a
    1144             :  * pivot tuple (with truncated -inf attributes) that we return false for.
    1145             :  */
    1146             : static bool
    1147      358532 : _bt_tuple_before_array_skeys(IndexScanDesc scan, ScanDirection dir,
    1148             :                              IndexTuple tuple, TupleDesc tupdesc, int tupnatts,
    1149             :                              bool readpagetup, int sktrig, bool *scanBehind)
    1150             : {
    1151      358532 :     BTScanOpaque so = (BTScanOpaque) scan->opaque;
    1152             : 
    1153             :     Assert(so->numArrayKeys);
    1154             :     Assert(so->numberOfKeys);
    1155             :     Assert(sktrig == 0 || readpagetup);
    1156             :     Assert(!readpagetup || scanBehind == NULL);
    1157             : 
    1158      358532 :     if (scanBehind)
    1159       87102 :         *scanBehind = false;
    1160             : 
    1161      361994 :     for (int ikey = sktrig; ikey < so->numberOfKeys; ikey++)
    1162             :     {
    1163      360934 :         ScanKey     cur = so->keyData + ikey;
    1164             :         Datum       tupdatum;
    1165             :         bool        tupnull;
    1166             :         int32       result;
    1167             : 
    1168             :         /* readpagetup calls require one ORDER proc comparison (at most) */
    1169             :         Assert(!readpagetup || ikey == sktrig);
    1170             : 
    1171             :         /*
    1172             :          * Once we reach a non-required scan key, we're completely done.
    1173             :          *
    1174             :          * Note: we deliberately don't consider the scan direction here.
    1175             :          * _bt_advance_array_keys caller requires that we track *scanBehind
    1176             :          * without concern for scan direction.
    1177             :          */
    1178      360934 :         if ((cur->sk_flags & (SK_BT_REQFWD | SK_BT_REQBKWD)) == 0)
    1179             :         {
    1180             :             Assert(!readpagetup);
    1181             :             Assert(ikey > sktrig || ikey == 0);
    1182      357472 :             return false;
    1183             :         }
    1184             : 
    1185      360934 :         if (cur->sk_attno > tupnatts)
    1186             :         {
    1187             :             Assert(!readpagetup);
    1188             : 
    1189             :             /*
    1190             :              * When we reach a high key's truncated attribute, assume that the
    1191             :              * tuple attribute's value is >= the scan's equality constraint
    1192             :              * scan keys (but set *scanBehind to let interested callers know
    1193             :              * that a truncated attribute might have affected our answer).
    1194             :              */
    1195          34 :             if (scanBehind)
    1196          34 :                 *scanBehind = true;
    1197             : 
    1198          34 :             return false;
    1199             :         }
    1200             : 
    1201             :         /*
    1202             :          * Deal with inequality strategy scan keys that _bt_check_compare set
    1203             :          * continuescan=false for
    1204             :          */
    1205      360900 :         if (cur->sk_strategy != BTEqualStrategyNumber)
    1206             :         {
    1207             :             /*
    1208             :              * When _bt_check_compare indicated that a required inequality
    1209             :              * scan key wasn't satisfied, there's no need to verify anything;
    1210             :              * caller always calls _bt_advance_array_keys with this sktrig.
    1211             :              */
    1212         618 :             if (readpagetup)
    1213         348 :                 return false;
    1214             : 
    1215             :             /*
    1216             :              * Otherwise we can't give up, since we must check all required
    1217             :              * scan keys (required in either direction) in order to correctly
    1218             :              * track *scanBehind for caller
    1219             :              */
    1220         270 :             continue;
    1221             :         }
    1222             : 
    1223      360282 :         tupdatum = index_getattr(tuple, cur->sk_attno, tupdesc, &tupnull);
    1224             : 
    1225      360282 :         if (likely(!(cur->sk_flags & (SK_BT_MINVAL | SK_BT_MAXVAL))))
    1226             :         {
    1227             :             /* Scankey has a valid/comparable sk_argument value */
    1228      357014 :             result = _bt_compare_array_skey(&so->orderProcs[ikey],
    1229             :                                             tupdatum, tupnull,
    1230             :                                             cur->sk_argument, cur);
    1231             : 
    1232      357014 :             if (result == 0)
    1233             :             {
    1234             :                 /*
    1235             :                  * Interpret result in a way that takes NEXT/PRIOR into
    1236             :                  * account
    1237             :                  */
    1238       17084 :                 if (cur->sk_flags & SK_BT_NEXT)
    1239       13862 :                     result = -1;
    1240        3222 :                 else if (cur->sk_flags & SK_BT_PRIOR)
    1241          30 :                     result = 1;
    1242             : 
    1243             :                 Assert(result == 0 || (cur->sk_flags & SK_BT_SKIP));
    1244             :             }
    1245             :         }
    1246             :         else
    1247             :         {
    1248        3268 :             BTArrayKeyInfo *array = NULL;
    1249             : 
    1250             :             /*
    1251             :              * Current array element/array = scan key value is a sentinel
    1252             :              * value that represents the lowest (or highest) possible value
    1253             :              * that's still within the range of the array.
    1254             :              *
    1255             :              * Like _bt_first, we only see MINVAL keys during forwards scans
    1256             :              * (and similarly only see MAXVAL keys during backwards scans).
    1257             :              * Even if the scan's direction changes, we'll stop at some higher
    1258             :              * order key before we can ever reach any MAXVAL (or MINVAL) keys.
    1259             :              * (However, unlike _bt_first we _can_ get to keys marked either
    1260             :              * NEXT or PRIOR, regardless of the scan's current direction.)
    1261             :              */
    1262             :             Assert(ScanDirectionIsForward(dir) ?
    1263             :                    !(cur->sk_flags & SK_BT_MAXVAL) :
    1264             :                    !(cur->sk_flags & SK_BT_MINVAL));
    1265             : 
    1266             :             /*
    1267             :              * There are no valid sk_argument values in MINVAL/MAXVAL keys.
    1268             :              * Check if tupdatum is within the range of skip array instead.
    1269             :              */
    1270        3794 :             for (int arrayidx = 0; arrayidx < so->numArrayKeys; arrayidx++)
    1271             :             {
    1272        3794 :                 array = &so->arrayKeys[arrayidx];
    1273        3794 :                 if (array->scan_key == ikey)
    1274        3268 :                     break;
    1275             :             }
    1276             : 
    1277        3268 :             _bt_binsrch_skiparray_skey(false, dir, tupdatum, tupnull,
    1278             :                                        array, cur, &result);
    1279             : 
    1280        3268 :             if (result == 0)
    1281             :             {
    1282             :                 /*
    1283             :                  * tupdatum satisfies both low_compare and high_compare, so
    1284             :                  * it's time to advance the array keys.
    1285             :                  *
    1286             :                  * Note: It's possible that the skip array will "advance" from
    1287             :                  * its MINVAL (or MAXVAL) representation to an alternative,
    1288             :                  * logically equivalent representation of the same value: a
    1289             :                  * representation where the = key gets a valid datum in its
    1290             :                  * sk_argument.  This is only possible when low_compare uses
    1291             :                  * the >= strategy (or high_compare uses the <= strategy).
    1292             :                  */
    1293        3262 :                 return false;
    1294             :             }
    1295             :         }
    1296             : 
    1297             :         /*
    1298             :          * Does this comparison indicate that caller must _not_ advance the
    1299             :          * scan's arrays just yet?
    1300             :          */
    1301      357020 :         if ((ScanDirectionIsForward(dir) && result < 0) ||
    1302        3252 :             (ScanDirectionIsBackward(dir) && result > 0))
    1303       75078 :             return true;
    1304             : 
    1305             :         /*
    1306             :          * Does this comparison indicate that caller should now advance the
    1307             :          * scan's arrays?  (Must be if we get here during a readpagetup call.)
    1308             :          */
    1309      281942 :         if (readpagetup || result != 0)
    1310             :         {
    1311             :             Assert(result != 0);
    1312      278750 :             return false;
    1313             :         }
    1314             : 
    1315             :         /*
    1316             :          * Inconclusive -- need to check later scan keys, too.
    1317             :          *
    1318             :          * This must be a finaltup precheck, or a call made from an assertion.
    1319             :          */
    1320             :         Assert(result == 0);
    1321             :     }
    1322             : 
    1323             :     Assert(!readpagetup);
    1324             : 
    1325        1060 :     return false;
    1326             : }
    1327             : 
    1328             : /*
    1329             :  * _bt_start_prim_scan() -- start scheduled primitive index scan?
    1330             :  *
    1331             :  * Returns true if _bt_checkkeys scheduled another primitive index scan, just
    1332             :  * as the last one ended.  Otherwise returns false, indicating that the array
    1333             :  * keys are now fully exhausted.
    1334             :  *
    1335             :  * Only call here during scans with one or more equality type array scan keys,
    1336             :  * after _bt_first or _bt_next return false.
    1337             :  */
    1338             : bool
    1339       89054 : _bt_start_prim_scan(IndexScanDesc scan, ScanDirection dir)
    1340             : {
    1341       89054 :     BTScanOpaque so = (BTScanOpaque) scan->opaque;
    1342             : 
    1343             :     Assert(so->numArrayKeys);
    1344             : 
    1345       89054 :     so->scanBehind = so->oppositeDirCheck = false;    /* reset */
    1346             : 
    1347             :     /*
    1348             :      * Array keys are advanced within _bt_checkkeys when the scan reaches the
    1349             :      * leaf level (more precisely, they're advanced when the scan reaches the
    1350             :      * end of each distinct set of array elements).  This process avoids
    1351             :      * repeat access to leaf pages (across multiple primitive index scans) by
    1352             :      * advancing the scan's array keys when it allows the primitive index scan
    1353             :      * to find nearby matching tuples (or when it eliminates ranges of array
    1354             :      * key space that can't possibly be satisfied by any index tuple).
    1355             :      *
    1356             :      * _bt_checkkeys sets a simple flag variable to schedule another primitive
    1357             :      * index scan.  The flag tells us what to do.
    1358             :      *
    1359             :      * We cannot rely on _bt_first always reaching _bt_checkkeys.  There are
    1360             :      * various cases where that won't happen.  For example, if the index is
    1361             :      * completely empty, then _bt_first won't call _bt_readpage/_bt_checkkeys.
    1362             :      * We also don't expect a call to _bt_checkkeys during searches for a
    1363             :      * non-existent value that happens to be lower/higher than any existing
    1364             :      * value in the index.
    1365             :      *
    1366             :      * We don't require special handling for these cases -- we don't need to
    1367             :      * be explicitly instructed to _not_ perform another primitive index scan.
    1368             :      * It's up to code under the control of _bt_first to always set the flag
    1369             :      * when another primitive index scan will be required.
    1370             :      *
    1371             :      * This works correctly, even with the tricky cases listed above, which
    1372             :      * all involve access to leaf pages "near the boundaries of the key space"
    1373             :      * (whether it's from a leftmost/rightmost page, or an imaginary empty
    1374             :      * leaf root page).  If _bt_checkkeys cannot be reached by a primitive
    1375             :      * index scan for one set of array keys, then it also won't be reached for
    1376             :      * any later set ("later" in terms of the direction that we scan the index
    1377             :      * and advance the arrays).  The array keys won't have advanced in these
    1378             :      * cases, but that's the correct behavior (even _bt_advance_array_keys
    1379             :      * won't always advance the arrays at the point they become "exhausted").
    1380             :      */
    1381       89054 :     if (so->needPrimScan)
    1382             :     {
    1383             :         Assert(_bt_verify_arrays_bt_first(scan, dir));
    1384             : 
    1385             :         /*
    1386             :          * Flag was set -- must call _bt_first again, which will reset the
    1387             :          * scan's needPrimScan flag
    1388             :          */
    1389       17960 :         return true;
    1390             :     }
    1391             : 
    1392             :     /* The top-level index scan ran out of tuples in this scan direction */
    1393       71094 :     if (scan->parallel_scan != NULL)
    1394          30 :         _bt_parallel_done(scan);
    1395             : 
    1396       71094 :     return false;
    1397             : }
    1398             : 
    1399             : /*
    1400             :  * _bt_advance_array_keys() -- Advance array elements using a tuple
    1401             :  *
    1402             :  * The scan always gets a new qual as a consequence of calling here (except
    1403             :  * when we determine that the top-level scan has run out of matching tuples).
    1404             :  * All later _bt_check_compare calls also use the same new qual that was first
    1405             :  * used here (at least until the next call here advances the keys once again).
    1406             :  * It's convenient to structure _bt_check_compare rechecks of caller's tuple
    1407             :  * (using the new qual) as one the steps of advancing the scan's array keys,
    1408             :  * so this function works as a wrapper around _bt_check_compare.
    1409             :  *
    1410             :  * Like _bt_check_compare, we'll set pstate.continuescan on behalf of the
    1411             :  * caller, and return a boolean indicating if caller's tuple satisfies the
    1412             :  * scan's new qual.  But unlike _bt_check_compare, we set so->needPrimScan
    1413             :  * when we set continuescan=false, indicating if a new primitive index scan
    1414             :  * has been scheduled (otherwise, the top-level scan has run out of tuples in
    1415             :  * the current scan direction).
    1416             :  *
    1417             :  * Caller must use _bt_tuple_before_array_skeys to determine if the current
    1418             :  * place in the scan is >= the current array keys _before_ calling here.
    1419             :  * We're responsible for ensuring that caller's tuple is <= the newly advanced
    1420             :  * required array keys once we return.  We try to find an exact match, but
    1421             :  * failing that we'll advance the array keys to whatever set of array elements
    1422             :  * comes next in the key space for the current scan direction.  Required array
    1423             :  * keys "ratchet forwards" (or backwards).  They can only advance as the scan
    1424             :  * itself advances through the index/key space.
    1425             :  *
    1426             :  * (The rules are the same for backwards scans, except that the operators are
    1427             :  * flipped: just replace the precondition's >= operator with a <=, and the
    1428             :  * postcondition's <= operator with a >=.  In other words, just swap the
    1429             :  * precondition with the postcondition.)
    1430             :  *
    1431             :  * We also deal with "advancing" non-required arrays here (or arrays that are
    1432             :  * treated as non-required for the duration of a _bt_readpage call).  Callers
    1433             :  * whose sktrig scan key is non-required specify sktrig_required=false.  These
    1434             :  * calls are the only exception to the general rule about always advancing the
    1435             :  * required array keys (the scan may not even have a required array).  These
    1436             :  * callers should just pass a NULL pstate (since there is never any question
    1437             :  * of stopping the scan).  No call to _bt_tuple_before_array_skeys is required
    1438             :  * ahead of these calls (it's already clear that any required scan keys must
    1439             :  * be satisfied by caller's tuple).
    1440             :  *
    1441             :  * Note that we deal with non-array required equality strategy scan keys as
    1442             :  * degenerate single element arrays here.  Obviously, they can never really
    1443             :  * advance in the way that real arrays can, but they must still affect how we
    1444             :  * advance real array scan keys (exactly like true array equality scan keys).
    1445             :  * We have to keep around a 3-way ORDER proc for these (using the "=" operator
    1446             :  * won't do), since in general whether the tuple is < or > _any_ unsatisfied
    1447             :  * required equality key influences how the scan's real arrays must advance.
    1448             :  *
    1449             :  * Note also that we may sometimes need to advance the array keys when the
    1450             :  * existing required array keys (and other required equality keys) are already
    1451             :  * an exact match for every corresponding value from caller's tuple.  We must
    1452             :  * do this for inequalities that _bt_check_compare set continuescan=false for.
    1453             :  * They'll advance the array keys here, just like any other scan key that
    1454             :  * _bt_check_compare stops on.  (This can even happen _after_ we advance the
    1455             :  * array keys, in which case we'll advance the array keys a second time.  That
    1456             :  * way _bt_checkkeys caller always has its required arrays advance to the
    1457             :  * maximum possible extent that its tuple will allow.)
    1458             :  */
    1459             : static bool
    1460      211190 : _bt_advance_array_keys(IndexScanDesc scan, BTReadPageState *pstate,
    1461             :                        IndexTuple tuple, int tupnatts, TupleDesc tupdesc,
    1462             :                        int sktrig, bool sktrig_required)
    1463             : {
    1464      211190 :     BTScanOpaque so = (BTScanOpaque) scan->opaque;
    1465      211190 :     Relation    rel = scan->indexRelation;
    1466      211190 :     ScanDirection dir = so->currPos.dir;
    1467      211190 :     int         arrayidx = 0;
    1468      211190 :     bool        beyond_end_advance = false,
    1469      211190 :                 skip_array_advanced = false,
    1470      211190 :                 has_required_opposite_direction_only = false,
    1471      211190 :                 all_required_satisfied = true,
    1472      211190 :                 all_satisfied = true;
    1473             : 
    1474             :     Assert(!so->needPrimScan && !so->scanBehind && !so->oppositeDirCheck);
    1475             :     Assert(_bt_verify_keys_with_arraykeys(scan));
    1476             : 
    1477      211190 :     if (sktrig_required)
    1478             :     {
    1479             :         /*
    1480             :          * Precondition array state assertion
    1481             :          */
    1482             :         Assert(!_bt_tuple_before_array_skeys(scan, dir, tuple, tupdesc,
    1483             :                                              tupnatts, false, 0, NULL));
    1484             : 
    1485             :         /*
    1486             :          * Once we return we'll have a new set of required array keys, so
    1487             :          * reset state used by "look ahead" optimization
    1488             :          */
    1489      202664 :         pstate->rechecks = 0;
    1490      202664 :         pstate->targetdistance = 0;
    1491             :     }
    1492        8526 :     else if (sktrig < so->numberOfKeys - 1 &&
    1493        8526 :              !(so->keyData[so->numberOfKeys - 1].sk_flags & SK_SEARCHARRAY))
    1494             :     {
    1495        8526 :         int         least_sign_ikey = so->numberOfKeys - 1;
    1496             :         bool        continuescan;
    1497             : 
    1498             :         /*
    1499             :          * Optimization: perform a precheck of the least significant key
    1500             :          * during !sktrig_required calls when it isn't already our sktrig
    1501             :          * (provided the precheck key is not itself an array).
    1502             :          *
    1503             :          * When the precheck works out we'll avoid an expensive binary search
    1504             :          * of sktrig's array (plus any other arrays before least_sign_ikey).
    1505             :          */
    1506             :         Assert(so->keyData[sktrig].sk_flags & SK_SEARCHARRAY);
    1507        8526 :         if (!_bt_check_compare(scan, dir, tuple, tupnatts, tupdesc, false,
    1508             :                                false, &continuescan,
    1509             :                                &least_sign_ikey))
    1510        2238 :             return false;
    1511             :     }
    1512             : 
    1513      604248 :     for (int ikey = 0; ikey < so->numberOfKeys; ikey++)
    1514             :     {
    1515      401062 :         ScanKey     cur = so->keyData + ikey;
    1516      401062 :         BTArrayKeyInfo *array = NULL;
    1517             :         Datum       tupdatum;
    1518      401062 :         bool        required = false,
    1519      401062 :                     required_opposite_direction_only = false,
    1520             :                     tupnull;
    1521             :         int32       result;
    1522      401062 :         int         set_elem = 0;
    1523             : 
    1524      401062 :         if (cur->sk_strategy == BTEqualStrategyNumber)
    1525             :         {
    1526             :             /* Manage array state */
    1527      352680 :             if (cur->sk_flags & SK_SEARCHARRAY)
    1528             :             {
    1529      219290 :                 array = &so->arrayKeys[arrayidx++];
    1530             :                 Assert(array->scan_key == ikey);
    1531             :             }
    1532             :         }
    1533             :         else
    1534             :         {
    1535             :             /*
    1536             :              * Are any inequalities required in the opposite direction only
    1537             :              * present here?
    1538             :              */
    1539       48382 :             if (((ScanDirectionIsForward(dir) &&
    1540       48382 :                   (cur->sk_flags & (SK_BT_REQBKWD))) ||
    1541           0 :                  (ScanDirectionIsBackward(dir) &&
    1542           0 :                   (cur->sk_flags & (SK_BT_REQFWD)))))
    1543       15838 :                 has_required_opposite_direction_only =
    1544       15838 :                     required_opposite_direction_only = true;
    1545             :         }
    1546             : 
    1547             :         /* Optimization: skip over known-satisfied scan keys */
    1548      401062 :         if (ikey < sktrig)
    1549       76388 :             continue;
    1550             : 
    1551      384714 :         if (cur->sk_flags & (SK_BT_REQFWD | SK_BT_REQBKWD))
    1552             :         {
    1553      384714 :             required = true;
    1554             : 
    1555      384714 :             if (cur->sk_attno > tupnatts)
    1556             :             {
    1557             :                 /* Set this just like _bt_tuple_before_array_skeys */
    1558             :                 Assert(sktrig < ikey);
    1559        2470 :                 so->scanBehind = true;
    1560             :             }
    1561             :         }
    1562             : 
    1563             :         /*
    1564             :          * Handle a required non-array scan key that the initial call to
    1565             :          * _bt_check_compare indicated triggered array advancement, if any.
    1566             :          *
    1567             :          * The non-array scan key's strategy will be <, <=, or = during a
    1568             :          * forwards scan (or any one of =, >=, or > during a backwards scan).
    1569             :          * It follows that the corresponding tuple attribute's value must now
    1570             :          * be either > or >= the scan key value (for backwards scans it must
    1571             :          * be either < or <= that value).
    1572             :          *
    1573             :          * If this is a required equality strategy scan key, this is just an
    1574             :          * optimization; _bt_tuple_before_array_skeys already confirmed that
    1575             :          * this scan key places us ahead of caller's tuple.  There's no need
    1576             :          * to repeat that work now.  (The same underlying principle also gets
    1577             :          * applied by the cur_elem_trig optimization used to speed up searches
    1578             :          * for the next array element.)
    1579             :          *
    1580             :          * If this is a required inequality strategy scan key, we _must_ rely
    1581             :          * on _bt_check_compare like this; we aren't capable of directly
    1582             :          * evaluating required inequality strategy scan keys here, on our own.
    1583             :          */
    1584      384714 :         if (ikey == sktrig && !array)
    1585             :         {
    1586             :             Assert(sktrig_required && required && all_required_satisfied);
    1587             : 
    1588             :             /* Use "beyond end" advancement.  See below for an explanation. */
    1589        7422 :             beyond_end_advance = true;
    1590        7422 :             all_satisfied = all_required_satisfied = false;
    1591             : 
    1592        7422 :             continue;
    1593             :         }
    1594             : 
    1595             :         /*
    1596             :          * Nothing more for us to do with an inequality strategy scan key that
    1597             :          * wasn't the one that _bt_check_compare stopped on, though.
    1598             :          *
    1599             :          * Note: if our later call to _bt_check_compare (to recheck caller's
    1600             :          * tuple) sets continuescan=false due to finding this same inequality
    1601             :          * unsatisfied (possible when it's required in the scan direction),
    1602             :          * we'll deal with it via a recursive "second pass" call.
    1603             :          */
    1604      377292 :         else if (cur->sk_strategy != BTEqualStrategyNumber)
    1605       47812 :             continue;
    1606             : 
    1607             :         /*
    1608             :          * Nothing for us to do with an equality strategy scan key that isn't
    1609             :          * marked required, either -- unless it's a non-required array
    1610             :          */
    1611      329480 :         else if (!required && !array)
    1612           0 :             continue;
    1613             : 
    1614             :         /*
    1615             :          * Here we perform steps for all array scan keys after a required
    1616             :          * array scan key whose binary search triggered "beyond end of array
    1617             :          * element" array advancement due to encountering a tuple attribute
    1618             :          * value > the closest matching array key (or < for backwards scans).
    1619             :          */
    1620      329480 :         if (beyond_end_advance)
    1621             :         {
    1622        1414 :             if (array)
    1623         596 :                 _bt_array_set_low_or_high(rel, cur, array,
    1624             :                                           ScanDirectionIsBackward(dir));
    1625             : 
    1626        1414 :             continue;
    1627             :         }
    1628             : 
    1629             :         /*
    1630             :          * Here we perform steps for all array scan keys after a required
    1631             :          * array scan key whose tuple attribute was < the closest matching
    1632             :          * array key when we dealt with it (or > for backwards scans).
    1633             :          *
    1634             :          * This earlier required array key already puts us ahead of caller's
    1635             :          * tuple in the key space (for the current scan direction).  We must
    1636             :          * make sure that subsequent lower-order array keys do not put us too
    1637             :          * far ahead (ahead of tuples that have yet to be seen by our caller).
    1638             :          * For example, when a tuple "(a, b) = (42, 5)" advances the array
    1639             :          * keys on "a" from 40 to 45, we must also set "b" to whatever the
    1640             :          * first array element for "b" is.  It would be wrong to allow "b" to
    1641             :          * be set based on the tuple value.
    1642             :          *
    1643             :          * Perform the same steps with truncated high key attributes.  You can
    1644             :          * think of this as a "binary search" for the element closest to the
    1645             :          * value -inf.  Again, the arrays must never get ahead of the scan.
    1646             :          */
    1647      328066 :         if (!all_required_satisfied || cur->sk_attno > tupnatts)
    1648             :         {
    1649        3392 :             if (array)
    1650         788 :                 _bt_array_set_low_or_high(rel, cur, array,
    1651             :                                           ScanDirectionIsForward(dir));
    1652             : 
    1653        3392 :             continue;
    1654             :         }
    1655             : 
    1656             :         /*
    1657             :          * Search in scankey's array for the corresponding tuple attribute
    1658             :          * value from caller's tuple
    1659             :          */
    1660      324674 :         tupdatum = index_getattr(tuple, cur->sk_attno, tupdesc, &tupnull);
    1661             : 
    1662      324674 :         if (array)
    1663             :         {
    1664      203334 :             bool        cur_elem_trig = (sktrig_required && ikey == sktrig);
    1665             : 
    1666             :             /*
    1667             :              * "Binary search" by checking if tupdatum/tupnull are within the
    1668             :              * range of the skip array
    1669             :              */
    1670      203334 :             if (array->num_elems == -1)
    1671      161710 :                 _bt_binsrch_skiparray_skey(cur_elem_trig, dir,
    1672             :                                            tupdatum, tupnull, array, cur,
    1673             :                                            &result);
    1674             : 
    1675             :             /*
    1676             :              * Binary search for the closest match from the SAOP array
    1677             :              */
    1678             :             else
    1679       41624 :                 set_elem = _bt_binsrch_array_skey(&so->orderProcs[ikey],
    1680             :                                                   cur_elem_trig, dir,
    1681             :                                                   tupdatum, tupnull, array, cur,
    1682             :                                                   &result);
    1683             :         }
    1684             :         else
    1685             :         {
    1686             :             Assert(required);
    1687             : 
    1688             :             /*
    1689             :              * This is a required non-array equality strategy scan key, which
    1690             :              * we'll treat as a degenerate single element array.
    1691             :              *
    1692             :              * This scan key's imaginary "array" can't really advance, but it
    1693             :              * can still roll over like any other array.  (Actually, this is
    1694             :              * no different to real single value arrays, which never advance
    1695             :              * without rolling over -- they can never truly advance, either.)
    1696             :              */
    1697      121340 :             result = _bt_compare_array_skey(&so->orderProcs[ikey],
    1698             :                                             tupdatum, tupnull,
    1699             :                                             cur->sk_argument, cur);
    1700             :         }
    1701             : 
    1702             :         /*
    1703             :          * Consider "beyond end of array element" array advancement.
    1704             :          *
    1705             :          * When the tuple attribute value is > the closest matching array key
    1706             :          * (or < in the backwards scan case), we need to ratchet this array
    1707             :          * forward (backward) by one increment, so that caller's tuple ends up
    1708             :          * being < final array value instead (or > final array value instead).
    1709             :          * This process has to work for all of the arrays, not just this one:
    1710             :          * it must "carry" to higher-order arrays when the set_elem that we
    1711             :          * just found happens to be the final one for the scan's direction.
    1712             :          * Incrementing (decrementing) set_elem itself isn't good enough.
    1713             :          *
    1714             :          * Our approach is to provisionally use set_elem as if it was an exact
    1715             :          * match now, then set each later/less significant array to whatever
    1716             :          * its final element is.  Once outside the loop we'll then "increment
    1717             :          * this array's set_elem" by calling _bt_advance_array_keys_increment.
    1718             :          * That way the process rolls over to higher order arrays as needed.
    1719             :          *
    1720             :          * Under this scheme any required arrays only ever ratchet forwards
    1721             :          * (or backwards), and always do so to the maximum possible extent
    1722             :          * that we can know will be safe without seeing the scan's next tuple.
    1723             :          * We don't need any special handling for required scan keys that lack
    1724             :          * a real array to advance, nor for redundant scan keys that couldn't
    1725             :          * be eliminated by _bt_preprocess_keys.  It won't matter if some of
    1726             :          * our "true" array scan keys (or even all of them) are non-required.
    1727             :          */
    1728      324674 :         if (sktrig_required && required &&
    1729      318386 :             ((ScanDirectionIsForward(dir) && result > 0) ||
    1730        1704 :              (ScanDirectionIsBackward(dir) && result < 0)))
    1731       23750 :             beyond_end_advance = true;
    1732             : 
    1733             :         Assert(all_required_satisfied && all_satisfied);
    1734      324674 :         if (result != 0)
    1735             :         {
    1736             :             /*
    1737             :              * Track whether caller's tuple satisfies our new post-advancement
    1738             :              * qual, for required scan keys, as well as for the entire set of
    1739             :              * interesting scan keys (all required scan keys plus non-required
    1740             :              * array scan keys are considered interesting.)
    1741             :              */
    1742      148466 :             all_satisfied = false;
    1743      148466 :             if (sktrig_required && required)
    1744      142700 :                 all_required_satisfied = false;
    1745             :             else
    1746             :             {
    1747             :                 /*
    1748             :                  * There's no need to advance the arrays using the best
    1749             :                  * available match for a non-required array.  Give up now.
    1750             :                  * (Though note that sktrig_required calls still have to do
    1751             :                  * all the usual post-advancement steps, including the recheck
    1752             :                  * call to _bt_check_compare.)
    1753             :                  */
    1754             :                 break;
    1755             :             }
    1756             :         }
    1757             : 
    1758             :         /* Advance array keys, even when we don't have an exact match */
    1759      318908 :         if (array)
    1760             :         {
    1761      197568 :             if (array->num_elems == -1)
    1762             :             {
    1763             :                 /* Skip array's new element is tupdatum (or MINVAL/MAXVAL) */
    1764      155944 :                 _bt_skiparray_set_element(rel, cur, array, result,
    1765             :                                           tupdatum, tupnull);
    1766      155944 :                 skip_array_advanced = true;
    1767             :             }
    1768       41624 :             else if (array->cur_elem != set_elem)
    1769             :             {
    1770             :                 /* SAOP array's new element is set_elem datum */
    1771       33492 :                 array->cur_elem = set_elem;
    1772       33492 :                 cur->sk_argument = array->elem_values[set_elem];
    1773             :             }
    1774             :         }
    1775             :     }
    1776             : 
    1777             :     /*
    1778             :      * Advance the array keys incrementally whenever "beyond end of array
    1779             :      * element" array advancement happens, so that advancement will carry to
    1780             :      * higher-order arrays (might exhaust all the scan's arrays instead, which
    1781             :      * ends the top-level scan).
    1782             :      */
    1783      208952 :     if (beyond_end_advance &&
    1784       31172 :         !_bt_advance_array_keys_increment(scan, dir, &skip_array_advanced))
    1785        8280 :         goto end_toplevel_scan;
    1786             : 
    1787             :     Assert(_bt_verify_keys_with_arraykeys(scan));
    1788             : 
    1789             :     /*
    1790             :      * Maintain a page-level count of the number of times the scan's array
    1791             :      * keys advanced in a way that affected at least one skip array
    1792             :      */
    1793      200672 :     if (sktrig_required && skip_array_advanced)
    1794      161956 :         pstate->nskipadvances++;
    1795             : 
    1796             :     /*
    1797             :      * Does tuple now satisfy our new qual?  Recheck with _bt_check_compare.
    1798             :      *
    1799             :      * Calls triggered by an unsatisfied required scan key, whose tuple now
    1800             :      * satisfies all required scan keys, but not all nonrequired array keys,
    1801             :      * will still require a recheck call to _bt_check_compare.  They'll still
    1802             :      * need its "second pass" handling of required inequality scan keys.
    1803             :      * (Might have missed a still-unsatisfied required inequality scan key
    1804             :      * that caller didn't detect as the sktrig scan key during its initial
    1805             :      * _bt_check_compare call that used the old/original qual.)
    1806             :      *
    1807             :      * Calls triggered by an unsatisfied nonrequired array scan key never need
    1808             :      * "second pass" handling of required inequalities (nor any other handling
    1809             :      * of any required scan key).  All that matters is whether caller's tuple
    1810             :      * satisfies the new qual, so it's safe to just skip the _bt_check_compare
    1811             :      * recheck when we've already determined that it can only return 'false'.
    1812             :      *
    1813             :      * Note: In practice most scan keys are marked required by preprocessing,
    1814             :      * if necessary by generating a preceding skip array.  We nevertheless
    1815             :      * often handle array keys marked required as if they were nonrequired.
    1816             :      * This behavior is requested by our _bt_check_compare caller, though only
    1817             :      * when it is passed "forcenonrequired=true" by _bt_checkkeys.
    1818             :      */
    1819      200672 :     if ((sktrig_required && all_required_satisfied) ||
    1820      148130 :         (!sktrig_required && all_satisfied))
    1821             :     {
    1822       53064 :         int         nsktrig = sktrig + 1;
    1823             :         bool        continuescan;
    1824             : 
    1825             :         Assert(all_required_satisfied);
    1826             : 
    1827             :         /* Recheck _bt_check_compare on behalf of caller */
    1828       53064 :         if (_bt_check_compare(scan, dir, tuple, tupnatts, tupdesc, false,
    1829             :                               false, &continuescan,
    1830       45298 :                               &nsktrig) &&
    1831       45298 :             !so->scanBehind)
    1832             :         {
    1833             :             /* This tuple satisfies the new qual */
    1834             :             Assert(all_satisfied && continuescan);
    1835             : 
    1836       42924 :             if (pstate)
    1837       42402 :                 pstate->continuescan = true;
    1838             : 
    1839       43146 :             return true;
    1840             :         }
    1841             : 
    1842             :         /*
    1843             :          * Consider "second pass" handling of required inequalities.
    1844             :          *
    1845             :          * It's possible that our _bt_check_compare call indicated that the
    1846             :          * scan should end due to some unsatisfied inequality that wasn't
    1847             :          * initially recognized as such by us.  Handle this by calling
    1848             :          * ourselves recursively, this time indicating that the trigger is the
    1849             :          * inequality that we missed first time around (and using a set of
    1850             :          * required array/equality keys that are now exact matches for tuple).
    1851             :          *
    1852             :          * We make a strong, general guarantee that every _bt_checkkeys call
    1853             :          * here will advance the array keys to the maximum possible extent
    1854             :          * that we can know to be safe based on caller's tuple alone.  If we
    1855             :          * didn't perform this step, then that guarantee wouldn't quite hold.
    1856             :          */
    1857       10140 :         if (unlikely(!continuescan))
    1858             :         {
    1859             :             bool        satisfied PG_USED_FOR_ASSERTS_ONLY;
    1860             : 
    1861             :             Assert(sktrig_required);
    1862             :             Assert(so->keyData[nsktrig].sk_strategy != BTEqualStrategyNumber);
    1863             : 
    1864             :             /*
    1865             :              * The tuple must use "beyond end" advancement during the
    1866             :              * recursive call, so we cannot possibly end up back here when
    1867             :              * recursing.  We'll consume a small, fixed amount of stack space.
    1868             :              */
    1869             :             Assert(!beyond_end_advance);
    1870             : 
    1871             :             /* Advance the array keys a second time using same tuple */
    1872         222 :             satisfied = _bt_advance_array_keys(scan, pstate, tuple, tupnatts,
    1873             :                                                tupdesc, nsktrig, true);
    1874             : 
    1875             :             /* This tuple doesn't satisfy the inequality */
    1876             :             Assert(!satisfied);
    1877         222 :             return false;
    1878             :         }
    1879             : 
    1880             :         /*
    1881             :          * Some non-required scan key (from new qual) still not satisfied.
    1882             :          *
    1883             :          * All scan keys required in the current scan direction must still be
    1884             :          * satisfied, though, so we can trust all_required_satisfied below.
    1885             :          */
    1886             :     }
    1887             : 
    1888             :     /*
    1889             :      * When we were called just to deal with "advancing" non-required arrays,
    1890             :      * this is as far as we can go (cannot stop the scan for these callers)
    1891             :      */
    1892      157526 :     if (!sktrig_required)
    1893             :     {
    1894             :         /* Caller's tuple doesn't match any qual */
    1895        5766 :         return false;
    1896             :     }
    1897             : 
    1898             :     /*
    1899             :      * Postcondition array state assertion (for still-unsatisfied tuples).
    1900             :      *
    1901             :      * By here we have established that the scan's required arrays (scan must
    1902             :      * have at least one required array) advanced, without becoming exhausted.
    1903             :      *
    1904             :      * Caller's tuple is now < the newly advanced array keys (or > when this
    1905             :      * is a backwards scan), except in the case where we only got this far due
    1906             :      * to an unsatisfied non-required scan key.  Verify that with an assert.
    1907             :      *
    1908             :      * Note: we don't just quit at this point when all required scan keys were
    1909             :      * found to be satisfied because we need to consider edge-cases involving
    1910             :      * scan keys required in the opposite direction only; those aren't tracked
    1911             :      * by all_required_satisfied.
    1912             :      */
    1913             :     Assert(_bt_tuple_before_array_skeys(scan, dir, tuple, tupdesc, tupnatts,
    1914             :                                         false, 0, NULL) ==
    1915             :            !all_required_satisfied);
    1916             : 
    1917             :     /*
    1918             :      * We generally permit primitive index scans to continue onto the next
    1919             :      * sibling page when the page's finaltup satisfies all required scan keys
    1920             :      * at the point where we're between pages.
    1921             :      *
    1922             :      * If caller's tuple is also the page's finaltup, and we see that required
    1923             :      * scan keys still aren't satisfied, start a new primitive index scan.
    1924             :      */
    1925      151760 :     if (!all_required_satisfied && pstate->finaltup == tuple)
    1926         584 :         goto new_prim_scan;
    1927             : 
    1928             :     /*
    1929             :      * Proactively check finaltup (don't wait until finaltup is reached by the
    1930             :      * scan) when it might well turn out to not be satisfied later on.
    1931             :      *
    1932             :      * Note: if so->scanBehind hasn't already been set for finaltup by us,
    1933             :      * it'll be set during this call to _bt_tuple_before_array_skeys.  Either
    1934             :      * way, it'll be set correctly (for the whole page) after this point.
    1935             :      */
    1936      238278 :     if (!all_required_satisfied && pstate->finaltup &&
    1937      174204 :         _bt_tuple_before_array_skeys(scan, dir, pstate->finaltup, tupdesc,
    1938      174204 :                                      BTreeTupleGetNAtts(pstate->finaltup, rel),
    1939             :                                      false, 0, &so->scanBehind))
    1940       17852 :         goto new_prim_scan;
    1941             : 
    1942             :     /*
    1943             :      * When we encounter a truncated finaltup high key attribute, we're
    1944             :      * optimistic about the chances of its corresponding required scan key
    1945             :      * being satisfied when we go on to recheck it against tuples from this
    1946             :      * page's right sibling leaf page.  We consider truncated attributes to be
    1947             :      * satisfied by required scan keys, which allows the primitive index scan
    1948             :      * to continue to the next leaf page.  We must set so->scanBehind to true
    1949             :      * to remember that the last page's finaltup had "satisfied" required scan
    1950             :      * keys for one or more truncated attribute values (scan keys required in
    1951             :      * _either_ scan direction).
    1952             :      *
    1953             :      * There is a chance that _bt_checkkeys (which checks so->scanBehind) will
    1954             :      * find that even the sibling leaf page's finaltup is < the new array
    1955             :      * keys.  When that happens, our optimistic policy will have incurred a
    1956             :      * single extra leaf page access that could have been avoided.
    1957             :      *
    1958             :      * A pessimistic policy would give backward scans a gratuitous advantage
    1959             :      * over forward scans.  We'd punish forward scans for applying more
    1960             :      * accurate information from the high key, rather than just using the
    1961             :      * final non-pivot tuple as finaltup, in the style of backward scans.
    1962             :      * Being pessimistic would also give some scans with non-required arrays a
    1963             :      * perverse advantage over similar scans that use required arrays instead.
    1964             :      *
    1965             :      * This is similar to our scan-level heuristics, below.  They also set
    1966             :      * scanBehind to speculatively continue the primscan onto the next page.
    1967             :      */
    1968      133324 :     if (so->scanBehind)
    1969             :     {
    1970             :         /* Truncated high key -- _bt_scanbehind_checkkeys recheck scheduled */
    1971             :     }
    1972             : 
    1973             :     /*
    1974             :      * Handle inequalities marked required in the opposite scan direction.
    1975             :      * They can also signal that we should start a new primitive index scan.
    1976             :      *
    1977             :      * It's possible that the scan is now positioned where "matching" tuples
    1978             :      * begin, and that caller's tuple satisfies all scan keys required in the
    1979             :      * current scan direction.  But if caller's tuple still doesn't satisfy
    1980             :      * other scan keys that are required in the opposite scan direction only
    1981             :      * (e.g., a required >= strategy scan key when scan direction is forward),
    1982             :      * it's still possible that there are many leaf pages before the page that
    1983             :      * _bt_first could skip straight to.  Groveling through all those pages
    1984             :      * will always give correct answers, but it can be very inefficient.  We
    1985             :      * must avoid needlessly scanning extra pages.
    1986             :      *
    1987             :      * Separately, it's possible that _bt_check_compare set continuescan=false
    1988             :      * for a scan key that's required in the opposite direction only.  This is
    1989             :      * a special case, that happens only when _bt_check_compare sees that the
    1990             :      * inequality encountered a NULL value.  This signals the end of non-NULL
    1991             :      * values in the current scan direction, which is reason enough to end the
    1992             :      * (primitive) scan.  If this happens at the start of a large group of
    1993             :      * NULL values, then we shouldn't expect to be called again until after
    1994             :      * the scan has already read indefinitely-many leaf pages full of tuples
    1995             :      * with NULL suffix values.  (_bt_first is expected to skip over the group
    1996             :      * of NULLs by applying a similar "deduce NOT NULL" rule of its own, which
    1997             :      * involves consing up an explicit SK_SEARCHNOTNULL key.)
    1998             :      *
    1999             :      * Apply a test against finaltup to detect and recover from the problem:
    2000             :      * if even finaltup doesn't satisfy such an inequality, we just skip by
    2001             :      * starting a new primitive index scan.  When we skip, we know for sure
    2002             :      * that all of the tuples on the current page following caller's tuple are
    2003             :      * also before the _bt_first-wise start of tuples for our new qual.  That
    2004             :      * at least suggests many more skippable pages beyond the current page.
    2005             :      * (when so->scanBehind and so->oppositeDirCheck are set, this'll happen
    2006             :      * when we test the next page's finaltup/high key instead.)
    2007             :      */
    2008      130916 :     else if (has_required_opposite_direction_only && pstate->finaltup &&
    2009        4326 :              unlikely(!_bt_oppodir_checkkeys(scan, dir, pstate->finaltup)))
    2010             :     {
    2011             :         /*
    2012             :          * Make sure that any SAOP arrays that were not marked required by
    2013             :          * preprocessing are reset to their first element for this direction
    2014             :          */
    2015           0 :         _bt_rewind_nonrequired_arrays(scan, dir);
    2016           0 :         goto new_prim_scan;
    2017             :     }
    2018             : 
    2019      130916 : continue_scan:
    2020             : 
    2021             :     /*
    2022             :      * Stick with the ongoing primitive index scan for now.
    2023             :      *
    2024             :      * It's possible that later tuples will also turn out to have values that
    2025             :      * are still < the now-current array keys (or > the current array keys).
    2026             :      * Our caller will handle this by performing what amounts to a linear
    2027             :      * search of the page, implemented by calling _bt_check_compare and then
    2028             :      * _bt_tuple_before_array_skeys for each tuple.
    2029             :      *
    2030             :      * This approach has various advantages over a binary search of the page.
    2031             :      * Repeated binary searches of the page (one binary search for every array
    2032             :      * advancement) won't outperform a continuous linear search.  While there
    2033             :      * are workloads that a naive linear search won't handle well, our caller
    2034             :      * has a "look ahead" fallback mechanism to deal with that problem.
    2035             :      */
    2036      134242 :     pstate->continuescan = true; /* Override _bt_check_compare */
    2037      134242 :     so->needPrimScan = false;    /* _bt_readpage has more tuples to check */
    2038             : 
    2039      134242 :     if (so->scanBehind)
    2040             :     {
    2041             :         /*
    2042             :          * Remember if recheck needs to call _bt_oppodir_checkkeys for next
    2043             :          * page's finaltup (see above comments about "Handle inequalities
    2044             :          * marked required in the opposite scan direction" for why).
    2045             :          */
    2046        3326 :         so->oppositeDirCheck = has_required_opposite_direction_only;
    2047             : 
    2048        3326 :         _bt_rewind_nonrequired_arrays(scan, dir);
    2049             : 
    2050             :         /*
    2051             :          * skip by setting "look ahead" mechanism's offnum for forwards scans
    2052             :          * (backwards scans check scanBehind flag directly instead)
    2053             :          */
    2054        3326 :         if (ScanDirectionIsForward(dir))
    2055        3308 :             pstate->skip = pstate->maxoff + 1;
    2056             :     }
    2057             : 
    2058             :     /* Caller's tuple doesn't match the new qual */
    2059      134242 :     return false;
    2060             : 
    2061       18436 : new_prim_scan:
    2062             : 
    2063             :     Assert(pstate->finaltup);    /* not on rightmost/leftmost page */
    2064             : 
    2065             :     /*
    2066             :      * Looks like another primitive index scan is required.  But consider
    2067             :      * continuing the current primscan based on scan-level heuristics.
    2068             :      *
    2069             :      * Continue the ongoing primitive scan (and schedule a recheck for when
    2070             :      * the scan arrives on the next sibling leaf page) when it has already
    2071             :      * read at least one leaf page before the one we're reading now.  This
    2072             :      * makes primscan scheduling more efficient when scanning subsets of an
    2073             :      * index with many distinct attribute values matching many array elements.
    2074             :      * It encourages fewer, larger primitive scans where that makes sense.
    2075             :      * This will in turn encourage _bt_readpage to apply the pstate.startikey
    2076             :      * optimization more often.
    2077             :      *
    2078             :      * Also continue the ongoing primitive index scan when it is still on the
    2079             :      * first page if there have been more than NSKIPADVANCES_THRESHOLD calls
    2080             :      * here that each advanced at least one of the scan's skip arrays
    2081             :      * (deliberately ignore advancements that only affected SAOP arrays here).
    2082             :      * A page that cycles through this many skip array elements is quite
    2083             :      * likely to neighbor similar pages, that we'll also need to read.
    2084             :      *
    2085             :      * Note: These heuristics aren't as aggressive as you might think.  We're
    2086             :      * conservative about allowing a primitive scan to step from the first
    2087             :      * leaf page it reads to the page's sibling page (we only allow it on
    2088             :      * first pages whose finaltup strongly suggests that it'll work out, as
    2089             :      * well as first pages that have a large number of skip array advances).
    2090             :      * Clearing this first page finaltup hurdle is a strong signal in itself.
    2091             :      *
    2092             :      * Note: The NSKIPADVANCES_THRESHOLD heuristic exists only to avoid
    2093             :      * pathological cases.  Specifically, cases where a skip scan should just
    2094             :      * behave like a traditional full index scan, but ends up "skipping" again
    2095             :      * and again, descending to the prior leaf page's direct sibling leaf page
    2096             :      * each time.  This misbehavior would otherwise be possible during scans
    2097             :      * that never quite manage to "clear the first page finaltup hurdle".
    2098             :      */
    2099       18436 :     if (!pstate->firstpage || pstate->nskipadvances > NSKIPADVANCES_THRESHOLD)
    2100             :     {
    2101             :         /* Schedule a recheck once on the next (or previous) page */
    2102         918 :         so->scanBehind = true;
    2103             : 
    2104             :         /* Continue the current primitive scan after all */
    2105         918 :         goto continue_scan;
    2106             :     }
    2107             : 
    2108             :     /*
    2109             :      * End this primitive index scan, but schedule another.
    2110             :      *
    2111             :      * Note: We make a soft assumption that the current scan direction will
    2112             :      * also be used within _bt_next, when it is asked to step off this page.
    2113             :      * It is up to _bt_next to cancel this scheduled primitive index scan
    2114             :      * whenever it steps to a page in the direction opposite currPos.dir.
    2115             :      */
    2116       17518 :     pstate->continuescan = false;    /* Tell _bt_readpage we're done... */
    2117       17518 :     so->needPrimScan = true; /* ...but call _bt_first again */
    2118             : 
    2119       17518 :     if (scan->parallel_scan)
    2120          36 :         _bt_parallel_primscan_schedule(scan, so->currPos.currPage);
    2121             : 
    2122             :     /* Caller's tuple doesn't match the new qual */
    2123       17518 :     return false;
    2124             : 
    2125        8280 : end_toplevel_scan:
    2126             : 
    2127             :     /*
    2128             :      * End the current primitive index scan, but don't schedule another.
    2129             :      *
    2130             :      * This ends the entire top-level scan in the current scan direction.
    2131             :      *
    2132             :      * Note: The scan's arrays (including any non-required arrays) are now in
    2133             :      * their final positions for the current scan direction.  If the scan
    2134             :      * direction happens to change, then the arrays will already be in their
    2135             :      * first positions for what will then be the current scan direction.
    2136             :      */
    2137        8280 :     pstate->continuescan = false;    /* Tell _bt_readpage we're done... */
    2138        8280 :     so->needPrimScan = false;    /* ...and don't call _bt_first again */
    2139             : 
    2140             :     /* Caller's tuple doesn't match any qual */
    2141        8280 :     return false;
    2142             : }
    2143             : 
    2144             : #ifdef USE_ASSERT_CHECKING
    2145             : /*
    2146             :  * Verify that the scan's qual state matches what we expect at the point that
    2147             :  * _bt_start_prim_scan is about to start a just-scheduled new primitive scan.
    2148             :  *
    2149             :  * We enforce a rule against non-required array scan keys: they must start out
    2150             :  * with whatever element is the first for the scan's current scan direction.
    2151             :  * See _bt_rewind_nonrequired_arrays comments for an explanation.
    2152             :  */
    2153             : static bool
    2154             : _bt_verify_arrays_bt_first(IndexScanDesc scan, ScanDirection dir)
    2155             : {
    2156             :     BTScanOpaque so = (BTScanOpaque) scan->opaque;
    2157             :     int         arrayidx = 0;
    2158             : 
    2159             :     for (int ikey = 0; ikey < so->numberOfKeys; ikey++)
    2160             :     {
    2161             :         ScanKey     cur = so->keyData + ikey;
    2162             :         BTArrayKeyInfo *array = NULL;
    2163             :         int         first_elem_dir;
    2164             : 
    2165             :         if (!(cur->sk_flags & SK_SEARCHARRAY) ||
    2166             :             cur->sk_strategy != BTEqualStrategyNumber)
    2167             :             continue;
    2168             : 
    2169             :         array = &so->arrayKeys[arrayidx++];
    2170             : 
    2171             :         if (((cur->sk_flags & SK_BT_REQFWD) && ScanDirectionIsForward(dir)) ||
    2172             :             ((cur->sk_flags & SK_BT_REQBKWD) && ScanDirectionIsBackward(dir)))
    2173             :             continue;
    2174             : 
    2175             :         if (ScanDirectionIsForward(dir))
    2176             :             first_elem_dir = 0;
    2177             :         else
    2178             :             first_elem_dir = array->num_elems - 1;
    2179             : 
    2180             :         if (array->cur_elem != first_elem_dir)
    2181             :             return false;
    2182             :     }
    2183             : 
    2184             :     return _bt_verify_keys_with_arraykeys(scan);
    2185             : }
    2186             : 
    2187             : /*
    2188             :  * Verify that the scan's "so->keyData[]" scan keys are in agreement with
    2189             :  * its array key state
    2190             :  */
    2191             : static bool
    2192             : _bt_verify_keys_with_arraykeys(IndexScanDesc scan)
    2193             : {
    2194             :     BTScanOpaque so = (BTScanOpaque) scan->opaque;
    2195             :     int         last_sk_attno = InvalidAttrNumber,
    2196             :                 arrayidx = 0;
    2197             : 
    2198             :     if (!so->qual_ok)
    2199             :         return false;
    2200             : 
    2201             :     for (int ikey = 0; ikey < so->numberOfKeys; ikey++)
    2202             :     {
    2203             :         ScanKey     cur = so->keyData + ikey;
    2204             :         BTArrayKeyInfo *array;
    2205             : 
    2206             :         if (cur->sk_strategy != BTEqualStrategyNumber ||
    2207             :             !(cur->sk_flags & SK_SEARCHARRAY))
    2208             :             continue;
    2209             : 
    2210             :         array = &so->arrayKeys[arrayidx++];
    2211             :         if (array->scan_key != ikey)
    2212             :             return false;
    2213             : 
    2214             :         if (array->num_elems == 0 || array->num_elems < -1)
    2215             :             return false;
    2216             : 
    2217             :         if (array->num_elems != -1 &&
    2218             :             cur->sk_argument != array->elem_values[array->cur_elem])
    2219             :             return false;
    2220             :         if (last_sk_attno > cur->sk_attno)
    2221             :             return false;
    2222             :         last_sk_attno = cur->sk_attno;
    2223             :     }
    2224             : 
    2225             :     if (arrayidx != so->numArrayKeys)
    2226             :         return false;
    2227             : 
    2228             :     return true;
    2229             : }
    2230             : #endif
    2231             : 
    2232             : /*
    2233             :  * Test whether an indextuple satisfies all the scankey conditions.
    2234             :  *
    2235             :  * Return true if so, false if not.  If the tuple fails to pass the qual,
    2236             :  * we also determine whether there's any need to continue the scan beyond
    2237             :  * this tuple, and set pstate.continuescan accordingly.  See comments for
    2238             :  * _bt_preprocess_keys() about how this is done.
    2239             :  *
    2240             :  * Forward scan callers can pass a high key tuple in the hopes of having
    2241             :  * us set *continuescan to false, and avoiding an unnecessary visit to
    2242             :  * the page to the right.
    2243             :  *
    2244             :  * Advances the scan's array keys when necessary for arrayKeys=true callers.
    2245             :  * Scans without any array keys must always pass arrayKeys=false.
    2246             :  *
    2247             :  * Also stops and starts primitive index scans for arrayKeys=true callers.
    2248             :  * Scans with array keys are required to set up page state that helps us with
    2249             :  * this.  The page's finaltup tuple (the page high key for a forward scan, or
    2250             :  * the page's first non-pivot tuple for a backward scan) must be set in
    2251             :  * pstate.finaltup ahead of the first call here for the page.  Set this to
    2252             :  * NULL for rightmost page (or the leftmost page for backwards scans).
    2253             :  *
    2254             :  * scan: index scan descriptor (containing a search-type scankey)
    2255             :  * pstate: page level input and output parameters
    2256             :  * arrayKeys: should we advance the scan's array keys if necessary?
    2257             :  * tuple: index tuple to test
    2258             :  * tupnatts: number of attributes in tupnatts (high key may be truncated)
    2259             :  */
    2260             : bool
    2261    59747594 : _bt_checkkeys(IndexScanDesc scan, BTReadPageState *pstate, bool arrayKeys,
    2262             :               IndexTuple tuple, int tupnatts)
    2263             : {
    2264    59747594 :     TupleDesc   tupdesc = RelationGetDescr(scan->indexRelation);
    2265    59747594 :     BTScanOpaque so = (BTScanOpaque) scan->opaque;
    2266    59747594 :     ScanDirection dir = so->currPos.dir;
    2267    59747594 :     int         ikey = pstate->startikey;
    2268             :     bool        res;
    2269             : 
    2270             :     Assert(BTreeTupleGetNAtts(tuple, scan->indexRelation) == tupnatts);
    2271             :     Assert(!so->needPrimScan && !so->scanBehind && !so->oppositeDirCheck);
    2272             :     Assert(arrayKeys || so->numArrayKeys == 0);
    2273             : 
    2274    59747594 :     res = _bt_check_compare(scan, dir, tuple, tupnatts, tupdesc, arrayKeys,
    2275    59747594 :                             pstate->forcenonrequired, &pstate->continuescan,
    2276             :                             &ikey);
    2277             : 
    2278             :     /*
    2279             :      * If _bt_check_compare relied on the pstate.startikey optimization, call
    2280             :      * again (in assert-enabled builds) to verify it didn't affect our answer.
    2281             :      *
    2282             :      * Note: we can't do this when !pstate.forcenonrequired, since any arrays
    2283             :      * before pstate.startikey won't have advanced on this page at all.
    2284             :      */
    2285             :     Assert(!pstate->forcenonrequired || arrayKeys);
    2286             : #ifdef USE_ASSERT_CHECKING
    2287             :     if (pstate->startikey > 0 && !pstate->forcenonrequired)
    2288             :     {
    2289             :         bool        dres,
    2290             :                     dcontinuescan;
    2291             :         int         dikey = 0;
    2292             : 
    2293             :         /* Pass arrayKeys=false to avoid array side-effects */
    2294             :         dres = _bt_check_compare(scan, dir, tuple, tupnatts, tupdesc, false,
    2295             :                                  pstate->forcenonrequired, &dcontinuescan,
    2296             :                                  &dikey);
    2297             :         Assert(res == dres);
    2298             :         Assert(pstate->continuescan == dcontinuescan);
    2299             : 
    2300             :         /*
    2301             :          * Should also get the same ikey result.  We need a slightly weaker
    2302             :          * assertion during arrayKeys calls, since they might be using an
    2303             :          * array that couldn't be marked required during preprocessing.
    2304             :          */
    2305             :         Assert(arrayKeys || ikey == dikey);
    2306             :         Assert(ikey <= dikey);
    2307             :     }
    2308             : #endif
    2309             : 
    2310             :     /*
    2311             :      * Only one _bt_check_compare call is required in the common case where
    2312             :      * there are no equality strategy array scan keys.  Otherwise we can only
    2313             :      * accept _bt_check_compare's answer unreservedly when it didn't set
    2314             :      * pstate.continuescan=false.
    2315             :      */
    2316    59747594 :     if (!arrayKeys || pstate->continuescan)
    2317    59493546 :         return res;
    2318             : 
    2319             :     /*
    2320             :      * _bt_check_compare call set continuescan=false in the presence of
    2321             :      * equality type array keys.  This could mean that the tuple is just past
    2322             :      * the end of matches for the current array keys.
    2323             :      *
    2324             :      * It's also possible that the scan is still _before_ the _start_ of
    2325             :      * tuples matching the current set of array keys.  Check for that first.
    2326             :      */
    2327             :     Assert(!pstate->forcenonrequired);
    2328      254048 :     if (_bt_tuple_before_array_skeys(scan, dir, tuple, tupdesc, tupnatts, true,
    2329             :                                      ikey, NULL))
    2330             :     {
    2331             :         /* Override _bt_check_compare, continue primitive scan */
    2332       51606 :         pstate->continuescan = true;
    2333             : 
    2334             :         /*
    2335             :          * We will end up here repeatedly given a group of tuples > the
    2336             :          * previous array keys and < the now-current keys (for a backwards
    2337             :          * scan it's just the same, though the operators swap positions).
    2338             :          *
    2339             :          * We must avoid allowing this linear search process to scan very many
    2340             :          * tuples from well before the start of tuples matching the current
    2341             :          * array keys (or from well before the point where we'll once again
    2342             :          * have to advance the scan's array keys).
    2343             :          *
    2344             :          * We keep the overhead under control by speculatively "looking ahead"
    2345             :          * to later still-unscanned items from this same leaf page.  We'll
    2346             :          * only attempt this once the number of tuples that the linear search
    2347             :          * process has examined starts to get out of hand.
    2348             :          */
    2349       51606 :         pstate->rechecks++;
    2350       51606 :         if (pstate->rechecks >= LOOK_AHEAD_REQUIRED_RECHECKS)
    2351             :         {
    2352             :             /* See if we should skip ahead within the current leaf page */
    2353       15404 :             _bt_checkkeys_look_ahead(scan, pstate, tupnatts, tupdesc);
    2354             : 
    2355             :             /*
    2356             :              * Might have set pstate.skip to a later page offset.  When that
    2357             :              * happens then _bt_readpage caller will inexpensively skip ahead
    2358             :              * to a later tuple from the same page (the one just after the
    2359             :              * tuple we successfully "looked ahead" to).
    2360             :              */
    2361             :         }
    2362             : 
    2363             :         /* This indextuple doesn't match the current qual, in any case */
    2364       51606 :         return false;
    2365             :     }
    2366             : 
    2367             :     /*
    2368             :      * Caller's tuple is >= the current set of array keys and other equality
    2369             :      * constraint scan keys (or <= if this is a backwards scan).  It's now
    2370             :      * clear that we _must_ advance any required array keys in lockstep with
    2371             :      * the scan.
    2372             :      */
    2373      202442 :     return _bt_advance_array_keys(scan, pstate, tuple, tupnatts, tupdesc,
    2374             :                                   ikey, true);
    2375             : }
    2376             : 
    2377             : /*
    2378             :  * Test whether caller's finaltup tuple is still before the start of matches
    2379             :  * for the current array keys.
    2380             :  *
    2381             :  * Called at the start of reading a page during a scan with array keys, though
    2382             :  * only when the so->scanBehind flag was set on the scan's prior page.
    2383             :  *
    2384             :  * Returns false if the tuple is still before the start of matches.  When that
    2385             :  * happens, caller should cut its losses and start a new primitive index scan.
    2386             :  * Otherwise returns true.
    2387             :  */
    2388             : bool
    2389        2802 : _bt_scanbehind_checkkeys(IndexScanDesc scan, ScanDirection dir,
    2390             :                          IndexTuple finaltup)
    2391             : {
    2392        2802 :     Relation    rel = scan->indexRelation;
    2393        2802 :     TupleDesc   tupdesc = RelationGetDescr(rel);
    2394        2802 :     BTScanOpaque so = (BTScanOpaque) scan->opaque;
    2395        2802 :     int         nfinaltupatts = BTreeTupleGetNAtts(finaltup, rel);
    2396             : 
    2397             :     Assert(so->numArrayKeys);
    2398             : 
    2399        2802 :     if (_bt_tuple_before_array_skeys(scan, dir, finaltup, tupdesc,
    2400             :                                      nfinaltupatts, false, 0, NULL))
    2401         442 :         return false;
    2402             : 
    2403        2360 :     if (!so->oppositeDirCheck)
    2404        2170 :         return true;
    2405             : 
    2406         190 :     return _bt_oppodir_checkkeys(scan, dir, finaltup);
    2407             : }
    2408             : 
    2409             : /*
    2410             :  * Test whether an indextuple fails to satisfy an inequality required in the
    2411             :  * opposite direction only.
    2412             :  *
    2413             :  * Caller's finaltup tuple is the page high key (for forwards scans), or the
    2414             :  * first non-pivot tuple (for backwards scans).  Called during scans with
    2415             :  * required array keys and required opposite-direction inequalities.
    2416             :  *
    2417             :  * Returns false if an inequality scan key required in the opposite direction
    2418             :  * only isn't satisfied (and any earlier required scan keys are satisfied).
    2419             :  * Otherwise returns true.
    2420             :  *
    2421             :  * An unsatisfied inequality required in the opposite direction only might
    2422             :  * well enable skipping over many leaf pages, provided another _bt_first call
    2423             :  * takes place.  This type of unsatisfied inequality won't usually cause
    2424             :  * _bt_checkkeys to stop the scan to consider array advancement/starting a new
    2425             :  * primitive index scan.
    2426             :  */
    2427             : static bool
    2428        4516 : _bt_oppodir_checkkeys(IndexScanDesc scan, ScanDirection dir,
    2429             :                       IndexTuple finaltup)
    2430             : {
    2431        4516 :     Relation    rel = scan->indexRelation;
    2432        4516 :     TupleDesc   tupdesc = RelationGetDescr(rel);
    2433        4516 :     BTScanOpaque so = (BTScanOpaque) scan->opaque;
    2434        4516 :     int         nfinaltupatts = BTreeTupleGetNAtts(finaltup, rel);
    2435             :     bool        continuescan;
    2436        4516 :     ScanDirection flipped = -dir;
    2437        4516 :     int         ikey = 0;
    2438             : 
    2439             :     Assert(so->numArrayKeys);
    2440             : 
    2441        4516 :     _bt_check_compare(scan, flipped, finaltup, nfinaltupatts, tupdesc, false,
    2442             :                       false, &continuescan,
    2443             :                       &ikey);
    2444             : 
    2445        4516 :     if (!continuescan && so->keyData[ikey].sk_strategy != BTEqualStrategyNumber)
    2446           0 :         return false;
    2447             : 
    2448        4516 :     return true;
    2449             : }
    2450             : 
    2451             : /*
    2452             :  * Determines an offset to the first scan key (an so->keyData[]-wise offset)
    2453             :  * that is _not_ guaranteed to be satisfied by every tuple from pstate.page,
    2454             :  * which is set in pstate.startikey for _bt_checkkeys calls for the page.
    2455             :  * This allows caller to save cycles on comparisons of a prefix of keys while
    2456             :  * reading pstate.page.
    2457             :  *
    2458             :  * Also determines if later calls to _bt_checkkeys (for pstate.page) should be
    2459             :  * forced to treat all required scan keys >= pstate.startikey as nonrequired
    2460             :  * (that is, if they're to be treated as if any SK_BT_REQFWD/SK_BT_REQBKWD
    2461             :  * markings that were set by preprocessing were not set at all, for the
    2462             :  * duration of _bt_checkkeys calls prior to the call for pstate.finaltup).
    2463             :  * This is indicated to caller by setting pstate.forcenonrequired.
    2464             :  *
    2465             :  * Call here at the start of reading a leaf page beyond the first one for the
    2466             :  * primitive index scan.  We consider all non-pivot tuples, so it doesn't make
    2467             :  * sense to call here when only a subset of those tuples can ever be read.
    2468             :  * This is also a good idea on performance grounds; not calling here when on
    2469             :  * the first page (first for the current primitive scan) avoids wasting cycles
    2470             :  * during selective point queries.  They typically don't stand to gain as much
    2471             :  * when we can set pstate.startikey, and are likely to notice the overhead of
    2472             :  * calling here.  (Also, allowing pstate.forcenonrequired to be set on a
    2473             :  * primscan's first page would mislead _bt_advance_array_keys, which expects
    2474             :  * pstate.nskipadvances to be representative of every first page's key space.)
    2475             :  *
    2476             :  * Caller must reset startikey and forcenonrequired ahead of the _bt_checkkeys
    2477             :  * call for pstate.finaltup iff we set forcenonrequired=true.  This will give
    2478             :  * _bt_checkkeys the opportunity to call _bt_advance_array_keys once more,
    2479             :  * with sktrig_required=true, to advance the arrays that were ignored during
    2480             :  * checks of all of the page's prior tuples.  Caller doesn't need to do this
    2481             :  * on the rightmost/leftmost page in the index (where pstate.finaltup isn't
    2482             :  * set), since forcenonrequired won't be set here by us in the first place.
    2483             :  */
    2484             : void
    2485       31892 : _bt_set_startikey(IndexScanDesc scan, BTReadPageState *pstate)
    2486             : {
    2487       31892 :     BTScanOpaque so = (BTScanOpaque) scan->opaque;
    2488       31892 :     Relation    rel = scan->indexRelation;
    2489       31892 :     TupleDesc   tupdesc = RelationGetDescr(rel);
    2490             :     ItemId      iid;
    2491             :     IndexTuple  firsttup,
    2492             :                 lasttup;
    2493       31892 :     int         startikey = 0,
    2494       31892 :                 arrayidx = 0,
    2495             :                 firstchangingattnum;
    2496       31892 :     bool        start_past_saop_eq = false;
    2497             : 
    2498             :     Assert(!so->scanBehind);
    2499             :     Assert(pstate->minoff < pstate->maxoff);
    2500             :     Assert(!pstate->firstpage);
    2501             :     Assert(pstate->startikey == 0);
    2502             :     Assert(!so->numArrayKeys || pstate->finaltup ||
    2503             :            P_RIGHTMOST(BTPageGetOpaque(pstate->page)) ||
    2504             :            P_LEFTMOST(BTPageGetOpaque(pstate->page)));
    2505             : 
    2506       31892 :     if (so->numberOfKeys == 0)
    2507       12894 :         return;
    2508             : 
    2509             :     /* minoff is an offset to the lowest non-pivot tuple on the page */
    2510       18998 :     iid = PageGetItemId(pstate->page, pstate->minoff);
    2511       18998 :     firsttup = (IndexTuple) PageGetItem(pstate->page, iid);
    2512             : 
    2513             :     /* maxoff is an offset to the highest non-pivot tuple on the page */
    2514       18998 :     iid = PageGetItemId(pstate->page, pstate->maxoff);
    2515       18998 :     lasttup = (IndexTuple) PageGetItem(pstate->page, iid);
    2516             : 
    2517             :     /* Determine the first attribute whose values change on caller's page */
    2518       18998 :     firstchangingattnum = _bt_keep_natts_fast(rel, firsttup, lasttup);
    2519             : 
    2520       28824 :     for (; startikey < so->numberOfKeys; startikey++)
    2521             :     {
    2522       22064 :         ScanKey     key = so->keyData + startikey;
    2523             :         BTArrayKeyInfo *array;
    2524             :         Datum       firstdatum,
    2525             :                     lastdatum;
    2526             :         bool        firstnull,
    2527             :                     lastnull;
    2528             :         int32       result;
    2529             : 
    2530             :         /*
    2531             :          * Determine if it's safe to set pstate.startikey to an offset to a
    2532             :          * key that comes after this key, by examining this key
    2533             :          */
    2534       22064 :         if (!(key->sk_flags & (SK_BT_REQFWD | SK_BT_REQBKWD)))
    2535             :         {
    2536             :             /* Scan key isn't marked required (corner case) */
    2537             :             Assert(!(key->sk_flags & SK_ROW_HEADER));
    2538       12238 :             break;              /* unsafe */
    2539             :         }
    2540       22064 :         if (key->sk_flags & SK_ROW_HEADER)
    2541             :         {
    2542             :             /*
    2543             :              * Can't let pstate.startikey get set to an ikey beyond a
    2544             :              * RowCompare inequality
    2545             :              */
    2546           0 :             break;              /* unsafe */
    2547             :         }
    2548       22064 :         if (key->sk_strategy != BTEqualStrategyNumber)
    2549             :         {
    2550             :             /*
    2551             :              * Scalar inequality key.
    2552             :              *
    2553             :              * It's definitely safe for _bt_checkkeys to avoid assessing this
    2554             :              * inequality when the page's first and last non-pivot tuples both
    2555             :              * satisfy the inequality (since the same must also be true of all
    2556             :              * the tuples in between these two).
    2557             :              *
    2558             :              * Unlike the "=" case, it doesn't matter if this attribute has
    2559             :              * more than one distinct value (though it _is_ necessary for any
    2560             :              * and all _prior_ attributes to contain no more than one distinct
    2561             :              * value amongst all of the tuples from pstate.page).
    2562             :              */
    2563        4886 :             if (key->sk_attno > firstchangingattnum)  /* >, not >= */
    2564         432 :                 break;          /* unsafe, preceding attr has multiple
    2565             :                                  * distinct values */
    2566             : 
    2567        4454 :             firstdatum = index_getattr(firsttup, key->sk_attno, tupdesc, &firstnull);
    2568        4454 :             lastdatum = index_getattr(lasttup, key->sk_attno, tupdesc, &lastnull);
    2569             : 
    2570        4454 :             if (key->sk_flags & SK_ISNULL)
    2571             :             {
    2572             :                 /* IS NOT NULL key */
    2573             :                 Assert(key->sk_flags & SK_SEARCHNOTNULL);
    2574             : 
    2575         196 :                 if (firstnull || lastnull)
    2576             :                     break;      /* unsafe */
    2577             : 
    2578             :                 /* Safe, IS NOT NULL key satisfied by every tuple */
    2579        9578 :                 continue;
    2580             :             }
    2581             : 
    2582             :             /* Test firsttup */
    2583        4258 :             if (firstnull ||
    2584        4258 :                 !DatumGetBool(FunctionCall2Coll(&key->sk_func,
    2585             :                                                 key->sk_collation, firstdatum,
    2586             :                                                 key->sk_argument)))
    2587             :                 break;          /* unsafe */
    2588             : 
    2589             :             /* Test lasttup */
    2590        4258 :             if (lastnull ||
    2591        4258 :                 !DatumGetBool(FunctionCall2Coll(&key->sk_func,
    2592             :                                                 key->sk_collation, lastdatum,
    2593             :                                                 key->sk_argument)))
    2594             :                 break;          /* unsafe */
    2595             : 
    2596             :             /* Safe, scalar inequality satisfied by every tuple */
    2597        4158 :             continue;
    2598             :         }
    2599             : 
    2600             :         /* Some = key (could be a scalar = key, could be an array = key) */
    2601             :         Assert(key->sk_strategy == BTEqualStrategyNumber);
    2602             : 
    2603       17178 :         if (!(key->sk_flags & SK_SEARCHARRAY))
    2604             :         {
    2605             :             /*
    2606             :              * Scalar = key (possibly an IS NULL key).
    2607             :              *
    2608             :              * It is unsafe to set pstate.startikey to an ikey beyond this
    2609             :              * key, unless the = key is satisfied by every possible tuple on
    2610             :              * the page (possible only when attribute has just one distinct
    2611             :              * value among all tuples on the page).
    2612             :              */
    2613       13664 :             if (key->sk_attno >= firstchangingattnum)
    2614       11002 :                 break;          /* unsafe, multiple distinct attr values */
    2615             : 
    2616        2662 :             firstdatum = index_getattr(firsttup, key->sk_attno, tupdesc,
    2617             :                                        &firstnull);
    2618        2662 :             if (key->sk_flags & SK_ISNULL)
    2619             :             {
    2620             :                 /* IS NULL key */
    2621             :                 Assert(key->sk_flags & SK_SEARCHNULL);
    2622             : 
    2623           0 :                 if (!firstnull)
    2624           0 :                     break;      /* unsafe */
    2625             : 
    2626             :                 /* Safe, IS NULL key satisfied by every tuple */
    2627           0 :                 continue;
    2628             :             }
    2629        2662 :             if (firstnull ||
    2630        2662 :                 !DatumGetBool(FunctionCall2Coll(&key->sk_func,
    2631             :                                                 key->sk_collation, firstdatum,
    2632             :                                                 key->sk_argument)))
    2633             :                 break;          /* unsafe */
    2634             : 
    2635             :             /* Safe, scalar = key satisfied by every tuple */
    2636        2662 :             continue;
    2637             :         }
    2638             : 
    2639             :         /* = array key (could be a SAOP array, could be a skip array) */
    2640        3514 :         array = &so->arrayKeys[arrayidx++];
    2641             :         Assert(array->scan_key == startikey);
    2642        3514 :         if (array->num_elems != -1)
    2643             :         {
    2644             :             /*
    2645             :              * SAOP array = key.
    2646             :              *
    2647             :              * Handle this like we handle scalar = keys (though binary search
    2648             :              * for a matching element, to avoid relying on key's sk_argument).
    2649             :              */
    2650         644 :             if (key->sk_attno >= firstchangingattnum)
    2651         644 :                 break;          /* unsafe, multiple distinct attr values */
    2652             : 
    2653           0 :             firstdatum = index_getattr(firsttup, key->sk_attno, tupdesc,
    2654             :                                        &firstnull);
    2655           0 :             _bt_binsrch_array_skey(&so->orderProcs[startikey],
    2656             :                                    false, NoMovementScanDirection,
    2657             :                                    firstdatum, firstnull, array, key,
    2658             :                                    &result);
    2659           0 :             if (result != 0)
    2660           0 :                 break;          /* unsafe */
    2661             : 
    2662             :             /* Safe, SAOP = key satisfied by every tuple */
    2663           0 :             start_past_saop_eq = true;
    2664           0 :             continue;
    2665             :         }
    2666             : 
    2667             :         /*
    2668             :          * Skip array = key
    2669             :          */
    2670             :         Assert(key->sk_flags & SK_BT_SKIP);
    2671        2870 :         if (array->null_elem)
    2672             :         {
    2673             :             /*
    2674             :              * Non-range skip array = key.
    2675             :              *
    2676             :              * Safe, non-range skip array "satisfied" by every tuple on page
    2677             :              * (safe even when "key->sk_attno > firstchangingattnum").
    2678             :              */
    2679        2562 :             continue;
    2680             :         }
    2681             : 
    2682             :         /*
    2683             :          * Range skip array = key.
    2684             :          *
    2685             :          * Handle this like we handle scalar inequality keys (but avoid using
    2686             :          * key's sk_argument directly, as in the SAOP array case).
    2687             :          */
    2688         308 :         if (key->sk_attno > firstchangingattnum)  /* >, not >= */
    2689          48 :             break;              /* unsafe, preceding attr has multiple
    2690             :                                  * distinct values */
    2691             : 
    2692         260 :         firstdatum = index_getattr(firsttup, key->sk_attno, tupdesc, &firstnull);
    2693         260 :         lastdatum = index_getattr(lasttup, key->sk_attno, tupdesc, &lastnull);
    2694             : 
    2695             :         /* Test firsttup */
    2696         260 :         _bt_binsrch_skiparray_skey(false, ForwardScanDirection,
    2697             :                                    firstdatum, firstnull, array, key,
    2698             :                                    &result);
    2699         260 :         if (result != 0)
    2700           0 :             break;              /* unsafe */
    2701             : 
    2702             :         /* Test lasttup */
    2703         260 :         _bt_binsrch_skiparray_skey(false, ForwardScanDirection,
    2704             :                                    lastdatum, lastnull, array, key,
    2705             :                                    &result);
    2706         260 :         if (result != 0)
    2707          12 :             break;              /* unsafe */
    2708             : 
    2709             :         /* Safe, range skip array satisfied by every tuple on page */
    2710             :     }
    2711             : 
    2712             :     /*
    2713             :      * Use of forcenonrequired is typically undesirable, since it'll force
    2714             :      * _bt_readpage caller to read every tuple on the page -- even though, in
    2715             :      * general, it might well be possible to end the scan on an earlier tuple.
    2716             :      * However, caller must use forcenonrequired when start_past_saop_eq=true,
    2717             :      * since the usual required array behavior might fail to roll over to the
    2718             :      * SAOP array.
    2719             :      *
    2720             :      * We always prefer forcenonrequired=true during scans with skip arrays
    2721             :      * (except on the first page of each primitive index scan), though -- even
    2722             :      * when "startikey == 0".  That way, _bt_advance_array_keys's low-order
    2723             :      * key precheck optimization can always be used (unless on the first page
    2724             :      * of the scan).  It seems slightly preferable to check more tuples when
    2725             :      * that allows us to do significantly less skip array maintenance.
    2726             :      */
    2727       18998 :     pstate->forcenonrequired = (start_past_saop_eq || so->skipScan);
    2728       18998 :     pstate->startikey = startikey;
    2729             : 
    2730             :     /*
    2731             :      * _bt_readpage caller is required to call _bt_checkkeys against page's
    2732             :      * finaltup with forcenonrequired=false whenever we initially set
    2733             :      * forcenonrequired=true.  That way the scan's arrays will reliably track
    2734             :      * its progress through the index's key space.
    2735             :      *
    2736             :      * We don't expect this when _bt_readpage caller has no finaltup due to
    2737             :      * its page being the rightmost (or the leftmost, during backwards scans).
    2738             :      * When we see that _bt_readpage has no finaltup, back out of everything.
    2739             :      */
    2740             :     Assert(!pstate->forcenonrequired || so->numArrayKeys);
    2741       18998 :     if (pstate->forcenonrequired && !pstate->finaltup)
    2742             :     {
    2743         480 :         pstate->forcenonrequired = false;
    2744         480 :         pstate->startikey = 0;
    2745             :     }
    2746             : }
    2747             : 
    2748             : /*
    2749             :  * Test whether an indextuple satisfies current scan condition.
    2750             :  *
    2751             :  * Return true if so, false if not.  If not, also sets *continuescan to false
    2752             :  * when it's also not possible for any later tuples to pass the current qual
    2753             :  * (with the scan's current set of array keys, in the current scan direction),
    2754             :  * in addition to setting *ikey to the so->keyData[] subscript/offset for the
    2755             :  * unsatisfied scan key (needed when caller must consider advancing the scan's
    2756             :  * array keys).
    2757             :  *
    2758             :  * This is a subroutine for _bt_checkkeys.  We provisionally assume that
    2759             :  * reaching the end of the current set of required keys (in particular the
    2760             :  * current required array keys) ends the ongoing (primitive) index scan.
    2761             :  * Callers without array keys should just end the scan right away when they
    2762             :  * find that continuescan has been set to false here by us.  Things are more
    2763             :  * complicated for callers with array keys.
    2764             :  *
    2765             :  * Callers with array keys must first consider advancing the arrays when
    2766             :  * continuescan has been set to false here by us.  They must then consider if
    2767             :  * it really does make sense to end the current (primitive) index scan, in
    2768             :  * light of everything that is known at that point.  (In general when we set
    2769             :  * continuescan=false for these callers it must be treated as provisional.)
    2770             :  *
    2771             :  * We deal with advancing unsatisfied non-required arrays directly, though.
    2772             :  * This is safe, since by definition non-required keys can't end the scan.
    2773             :  * This is just how we determine if non-required arrays are just unsatisfied
    2774             :  * by the current array key, or if they're truly unsatisfied (that is, if
    2775             :  * they're unsatisfied by every possible array key).
    2776             :  *
    2777             :  * Pass advancenonrequired=false to avoid all array related side effects.
    2778             :  * This allows _bt_advance_array_keys caller to avoid infinite recursion.
    2779             :  *
    2780             :  * Pass forcenonrequired=true to instruct us to treat all keys as nonrequired.
    2781             :  * This is used to make it safe to temporarily stop properly maintaining the
    2782             :  * scan's required arrays.  _bt_checkkeys caller (_bt_readpage, actually)
    2783             :  * determines a prefix of keys that must satisfy every possible corresponding
    2784             :  * index attribute value from its page, which is passed to us via *ikey arg
    2785             :  * (this is the first key that might be unsatisfied by tuples on the page).
    2786             :  * Obviously, we won't maintain any array keys from before *ikey, so it's
    2787             :  * quite possible for such arrays to "fall behind" the index's keyspace.
    2788             :  * Caller will need to "catch up" by passing forcenonrequired=true (alongside
    2789             :  * an *ikey=0) once the page's finaltup is reached.
    2790             :  *
    2791             :  * Note: it's safe to pass an *ikey > 0 with forcenonrequired=false, but only
    2792             :  * when caller determines that it won't affect array maintenance.
    2793             :  */
    2794             : static bool
    2795    59813700 : _bt_check_compare(IndexScanDesc scan, ScanDirection dir,
    2796             :                   IndexTuple tuple, int tupnatts, TupleDesc tupdesc,
    2797             :                   bool advancenonrequired, bool forcenonrequired,
    2798             :                   bool *continuescan, int *ikey)
    2799             : {
    2800    59813700 :     BTScanOpaque so = (BTScanOpaque) scan->opaque;
    2801             : 
    2802             :     Assert(!forcenonrequired || advancenonrequired);
    2803             : 
    2804    59813700 :     *continuescan = true;       /* default assumption */
    2805             : 
    2806   114593122 :     for (; *ikey < so->numberOfKeys; (*ikey)++)
    2807             :     {
    2808    67029882 :         ScanKey     key = so->keyData + *ikey;
    2809             :         Datum       datum;
    2810             :         bool        isNull;
    2811    67029882 :         bool        requiredSameDir = false,
    2812    67029882 :                     requiredOppositeDirOnly = false;
    2813             : 
    2814             :         /*
    2815             :          * Check if the key is required in the current scan direction, in the
    2816             :          * opposite scan direction _only_, or in neither direction (except
    2817             :          * when we're forced to treat all scan keys as nonrequired)
    2818             :          */
    2819    67029882 :         if (forcenonrequired)
    2820             :         {
    2821             :             /* treating scan's keys as non-required */
    2822             :         }
    2823    66579358 :         else if (((key->sk_flags & SK_BT_REQFWD) && ScanDirectionIsForward(dir)) ||
    2824    14099562 :                  ((key->sk_flags & SK_BT_REQBKWD) && ScanDirectionIsBackward(dir)))
    2825    52504596 :             requiredSameDir = true;
    2826    14074762 :         else if (((key->sk_flags & SK_BT_REQFWD) && ScanDirectionIsBackward(dir)) ||
    2827     5445962 :                  ((key->sk_flags & SK_BT_REQBKWD) && ScanDirectionIsForward(dir)))
    2828    14074762 :             requiredOppositeDirOnly = true;
    2829             : 
    2830    67029882 :         if (key->sk_attno > tupnatts)
    2831             :         {
    2832             :             /*
    2833             :              * This attribute is truncated (must be high key).  The value for
    2834             :              * this attribute in the first non-pivot tuple on the page to the
    2835             :              * right could be any possible value.  Assume that truncated
    2836             :              * attribute passes the qual.
    2837             :              */
    2838             :             Assert(BTreeTupleIsPivot(tuple));
    2839    18896634 :             continue;
    2840             :         }
    2841             : 
    2842             :         /*
    2843             :          * A skip array scan key uses one of several sentinel values.  We just
    2844             :          * fall back on _bt_tuple_before_array_skeys when we see such a value.
    2845             :          */
    2846    67027412 :         if (key->sk_flags & (SK_BT_MINVAL | SK_BT_MAXVAL |
    2847             :                              SK_BT_NEXT | SK_BT_PRIOR))
    2848             :         {
    2849             :             Assert(key->sk_flags & SK_SEARCHARRAY);
    2850             :             Assert(key->sk_flags & SK_BT_SKIP);
    2851             :             Assert(requiredSameDir || forcenonrequired);
    2852             : 
    2853             :             /*
    2854             :              * Cannot fall back on _bt_tuple_before_array_skeys when we're
    2855             :              * treating the scan's keys as nonrequired, though.  Just handle
    2856             :              * this like any other non-required equality-type array key.
    2857             :              */
    2858       33574 :             if (forcenonrequired)
    2859    12250460 :                 return _bt_advance_array_keys(scan, NULL, tuple, tupnatts,
    2860             :                                               tupdesc, *ikey, false);
    2861             : 
    2862       31546 :             *continuescan = false;
    2863       31546 :             return false;
    2864             :         }
    2865             : 
    2866             :         /* row-comparison keys need special processing */
    2867    66993838 :         if (key->sk_flags & SK_ROW_HEADER)
    2868             :         {
    2869        2448 :             if (_bt_check_rowcompare(key, tuple, tupnatts, tupdesc, dir,
    2870             :                                      forcenonrequired, continuescan))
    2871        2382 :                 continue;
    2872          66 :             return false;
    2873             :         }
    2874             : 
    2875    66991390 :         datum = index_getattr(tuple,
    2876    66991390 :                               key->sk_attno,
    2877             :                               tupdesc,
    2878             :                               &isNull);
    2879             : 
    2880    66991390 :         if (key->sk_flags & SK_ISNULL)
    2881             :         {
    2882             :             /* Handle IS NULL/NOT NULL tests */
    2883    18909506 :             if (key->sk_flags & SK_SEARCHNULL)
    2884             :             {
    2885       18080 :                 if (isNull)
    2886         428 :                     continue;   /* tuple satisfies this qual */
    2887             :             }
    2888             :             else
    2889             :             {
    2890             :                 Assert(key->sk_flags & SK_SEARCHNOTNULL);
    2891             :                 Assert(!(key->sk_flags & SK_BT_SKIP));
    2892    18891426 :                 if (!isNull)
    2893    18891354 :                     continue;   /* tuple satisfies this qual */
    2894             :             }
    2895             : 
    2896             :             /*
    2897             :              * Tuple fails this qual.  If it's a required qual for the current
    2898             :              * scan direction, then we can conclude no further tuples will
    2899             :              * pass, either.
    2900             :              */
    2901       17724 :             if (requiredSameDir)
    2902         156 :                 *continuescan = false;
    2903       17568 :             else if (unlikely(key->sk_flags & SK_BT_SKIP))
    2904             :             {
    2905             :                 /*
    2906             :                  * If we're treating scan keys as nonrequired, and encounter a
    2907             :                  * skip array scan key whose current element is NULL, then it
    2908             :                  * must be a non-range skip array.  It must be satisfied, so
    2909             :                  * there's no need to call _bt_advance_array_keys to check.
    2910             :                  */
    2911             :                 Assert(forcenonrequired && *ikey > 0);
    2912           0 :                 continue;
    2913             :             }
    2914             : 
    2915             :             /*
    2916             :              * This indextuple doesn't match the qual.
    2917             :              */
    2918       17724 :             return false;
    2919             :         }
    2920             : 
    2921    48081884 :         if (isNull)
    2922             :         {
    2923         228 :             if (key->sk_flags & SK_BT_NULLS_FIRST)
    2924             :             {
    2925             :                 /*
    2926             :                  * Since NULLs are sorted before non-NULLs, we know we have
    2927             :                  * reached the lower limit of the range of values for this
    2928             :                  * index attr.  On a backward scan, we can stop if this qual
    2929             :                  * is one of the "must match" subset.  We can stop regardless
    2930             :                  * of whether the qual is > or <, so long as it's required,
    2931             :                  * because it's not possible for any future tuples to pass. On
    2932             :                  * a forward scan, however, we must keep going, because we may
    2933             :                  * have initially positioned to the start of the index.
    2934             :                  * (_bt_advance_array_keys also relies on this behavior during
    2935             :                  * forward scans.)
    2936             :                  */
    2937           0 :                 if ((requiredSameDir || requiredOppositeDirOnly) &&
    2938             :                     ScanDirectionIsBackward(dir))
    2939           0 :                     *continuescan = false;
    2940             :             }
    2941             :             else
    2942             :             {
    2943             :                 /*
    2944             :                  * Since NULLs are sorted after non-NULLs, we know we have
    2945             :                  * reached the upper limit of the range of values for this
    2946             :                  * index attr.  On a forward scan, we can stop if this qual is
    2947             :                  * one of the "must match" subset.  We can stop regardless of
    2948             :                  * whether the qual is > or <, so long as it's required,
    2949             :                  * because it's not possible for any future tuples to pass. On
    2950             :                  * a backward scan, however, we must keep going, because we
    2951             :                  * may have initially positioned to the end of the index.
    2952             :                  * (_bt_advance_array_keys also relies on this behavior during
    2953             :                  * backward scans.)
    2954             :                  */
    2955         228 :                 if ((requiredSameDir || requiredOppositeDirOnly) &&
    2956             :                     ScanDirectionIsForward(dir))
    2957         222 :                     *continuescan = false;
    2958             :             }
    2959             : 
    2960             :             /*
    2961             :              * In any case, this indextuple doesn't match the qual.
    2962             :              */
    2963         228 :             return false;
    2964             :         }
    2965             : 
    2966    48081656 :         if (!DatumGetBool(FunctionCall2Coll(&key->sk_func, key->sk_collation,
    2967             :                                             datum, key->sk_argument)))
    2968             :         {
    2969             :             /*
    2970             :              * Tuple fails this qual.  If it's a required qual for the current
    2971             :              * scan direction, then we can conclude no further tuples will
    2972             :              * pass, either.
    2973             :              *
    2974             :              * Note: because we stop the scan as soon as any required equality
    2975             :              * qual fails, it is critical that equality quals be used for the
    2976             :              * initial positioning in _bt_first() when they are available. See
    2977             :              * comments in _bt_first().
    2978             :              */
    2979    12198868 :             if (requiredSameDir)
    2980    11810196 :                 *continuescan = false;
    2981             : 
    2982             :             /*
    2983             :              * If this is a non-required equality-type array key, the tuple
    2984             :              * needs to be checked against every possible array key.  Handle
    2985             :              * this by "advancing" the scan key's array to a matching value
    2986             :              * (if we're successful then the tuple might match the qual).
    2987             :              */
    2988      388672 :             else if (advancenonrequired &&
    2989      381128 :                      key->sk_strategy == BTEqualStrategyNumber &&
    2990      291916 :                      (key->sk_flags & SK_SEARCHARRAY))
    2991        6498 :                 return _bt_advance_array_keys(scan, NULL, tuple, tupnatts,
    2992             :                                               tupdesc, *ikey, false);
    2993             : 
    2994             :             /*
    2995             :              * This indextuple doesn't match the qual.
    2996             :              */
    2997    12192370 :             return false;
    2998             :         }
    2999             :     }
    3000             : 
    3001             :     /* If we get here, the tuple passes all index quals. */
    3002    47563240 :     return true;
    3003             : }
    3004             : 
    3005             : /*
    3006             :  * Test whether an indextuple satisfies a row-comparison scan condition.
    3007             :  *
    3008             :  * Return true if so, false if not.  If not, also clear *continuescan if
    3009             :  * it's not possible for any future tuples in the current scan direction
    3010             :  * to pass the qual.
    3011             :  *
    3012             :  * This is a subroutine for _bt_checkkeys/_bt_check_compare.
    3013             :  */
    3014             : static bool
    3015        2448 : _bt_check_rowcompare(ScanKey skey, IndexTuple tuple, int tupnatts,
    3016             :                      TupleDesc tupdesc, ScanDirection dir,
    3017             :                      bool forcenonrequired, bool *continuescan)
    3018             : {
    3019        2448 :     ScanKey     subkey = (ScanKey) DatumGetPointer(skey->sk_argument);
    3020        2448 :     int32       cmpresult = 0;
    3021             :     bool        result;
    3022             : 
    3023             :     /* First subkey should be same as the header says */
    3024             :     Assert(subkey->sk_attno == skey->sk_attno);
    3025             : 
    3026             :     /* Loop over columns of the row condition */
    3027             :     for (;;)
    3028         240 :     {
    3029             :         Datum       datum;
    3030             :         bool        isNull;
    3031             : 
    3032             :         Assert(subkey->sk_flags & SK_ROW_MEMBER);
    3033             : 
    3034        2688 :         if (subkey->sk_attno > tupnatts)
    3035             :         {
    3036             :             /*
    3037             :              * This attribute is truncated (must be high key).  The value for
    3038             :              * this attribute in the first non-pivot tuple on the page to the
    3039             :              * right could be any possible value.  Assume that truncated
    3040             :              * attribute passes the qual.
    3041             :              */
    3042             :             Assert(BTreeTupleIsPivot(tuple));
    3043           6 :             cmpresult = 0;
    3044           6 :             if (subkey->sk_flags & SK_ROW_END)
    3045           6 :                 break;
    3046           0 :             subkey++;
    3047           0 :             continue;
    3048             :         }
    3049             : 
    3050        2682 :         datum = index_getattr(tuple,
    3051        2682 :                               subkey->sk_attno,
    3052             :                               tupdesc,
    3053             :                               &isNull);
    3054             : 
    3055        2682 :         if (isNull)
    3056             :         {
    3057          48 :             if (forcenonrequired)
    3058             :             {
    3059             :                 /* treating scan's keys as non-required */
    3060             :             }
    3061          48 :             else if (subkey->sk_flags & SK_BT_NULLS_FIRST)
    3062             :             {
    3063             :                 /*
    3064             :                  * Since NULLs are sorted before non-NULLs, we know we have
    3065             :                  * reached the lower limit of the range of values for this
    3066             :                  * index attr.  On a backward scan, we can stop if this qual
    3067             :                  * is one of the "must match" subset.  We can stop regardless
    3068             :                  * of whether the qual is > or <, so long as it's required,
    3069             :                  * because it's not possible for any future tuples to pass. On
    3070             :                  * a forward scan, however, we must keep going, because we may
    3071             :                  * have initially positioned to the start of the index.
    3072             :                  * (_bt_advance_array_keys also relies on this behavior during
    3073             :                  * forward scans.)
    3074             :                  */
    3075           0 :                 if ((subkey->sk_flags & (SK_BT_REQFWD | SK_BT_REQBKWD)) &&
    3076             :                     ScanDirectionIsBackward(dir))
    3077           0 :                     *continuescan = false;
    3078             :             }
    3079             :             else
    3080             :             {
    3081             :                 /*
    3082             :                  * Since NULLs are sorted after non-NULLs, we know we have
    3083             :                  * reached the upper limit of the range of values for this
    3084             :                  * index attr.  On a forward scan, we can stop if this qual is
    3085             :                  * one of the "must match" subset.  We can stop regardless of
    3086             :                  * whether the qual is > or <, so long as it's required,
    3087             :                  * because it's not possible for any future tuples to pass. On
    3088             :                  * a backward scan, however, we must keep going, because we
    3089             :                  * may have initially positioned to the end of the index.
    3090             :                  * (_bt_advance_array_keys also relies on this behavior during
    3091             :                  * backward scans.)
    3092             :                  */
    3093          48 :                 if ((subkey->sk_flags & (SK_BT_REQFWD | SK_BT_REQBKWD)) &&
    3094             :                     ScanDirectionIsForward(dir))
    3095           0 :                     *continuescan = false;
    3096             :             }
    3097             : 
    3098             :             /*
    3099             :              * In any case, this indextuple doesn't match the qual.
    3100             :              */
    3101          60 :             return false;
    3102             :         }
    3103             : 
    3104        2634 :         if (subkey->sk_flags & SK_ISNULL)
    3105             :         {
    3106             :             /*
    3107             :              * Unlike the simple-scankey case, this isn't a disallowed case
    3108             :              * (except when it's the first row element that has the NULL arg).
    3109             :              * But it can never match.  If all the earlier row comparison
    3110             :              * columns are required for the scan direction, we can stop the
    3111             :              * scan, because there can't be another tuple that will succeed.
    3112             :              */
    3113             :             Assert(subkey != (ScanKey) DatumGetPointer(skey->sk_argument));
    3114          12 :             subkey--;
    3115          12 :             if (forcenonrequired)
    3116             :             {
    3117             :                 /* treating scan's keys as non-required */
    3118             :             }
    3119          12 :             else if ((subkey->sk_flags & SK_BT_REQFWD) &&
    3120             :                      ScanDirectionIsForward(dir))
    3121           6 :                 *continuescan = false;
    3122           6 :             else if ((subkey->sk_flags & SK_BT_REQBKWD) &&
    3123             :                      ScanDirectionIsBackward(dir))
    3124           6 :                 *continuescan = false;
    3125          12 :             return false;
    3126             :         }
    3127             : 
    3128             :         /* Perform the test --- three-way comparison not bool operator */
    3129        2622 :         cmpresult = DatumGetInt32(FunctionCall2Coll(&subkey->sk_func,
    3130             :                                                     subkey->sk_collation,
    3131             :                                                     datum,
    3132             :                                                     subkey->sk_argument));
    3133             : 
    3134        2622 :         if (subkey->sk_flags & SK_BT_DESC)
    3135           0 :             INVERT_COMPARE_RESULT(cmpresult);
    3136             : 
    3137             :         /* Done comparing if unequal, else advance to next column */
    3138        2622 :         if (cmpresult != 0)
    3139        2382 :             break;
    3140             : 
    3141         240 :         if (subkey->sk_flags & SK_ROW_END)
    3142           0 :             break;
    3143         240 :         subkey++;
    3144             :     }
    3145             : 
    3146             :     /*
    3147             :      * At this point cmpresult indicates the overall result of the row
    3148             :      * comparison, and subkey points to the deciding column (or the last
    3149             :      * column if the result is "=").
    3150             :      */
    3151        2388 :     switch (subkey->sk_strategy)
    3152             :     {
    3153             :             /* EQ and NE cases aren't allowed here */
    3154         186 :         case BTLessStrategyNumber:
    3155         186 :             result = (cmpresult < 0);
    3156         186 :             break;
    3157        1590 :         case BTLessEqualStrategyNumber:
    3158        1590 :             result = (cmpresult <= 0);
    3159        1590 :             break;
    3160         240 :         case BTGreaterEqualStrategyNumber:
    3161         240 :             result = (cmpresult >= 0);
    3162         240 :             break;
    3163         372 :         case BTGreaterStrategyNumber:
    3164         372 :             result = (cmpresult > 0);
    3165         372 :             break;
    3166           0 :         default:
    3167           0 :             elog(ERROR, "unexpected strategy number %d", subkey->sk_strategy);
    3168             :             result = 0;         /* keep compiler quiet */
    3169             :             break;
    3170             :     }
    3171             : 
    3172        2388 :     if (!result && !forcenonrequired)
    3173             :     {
    3174             :         /*
    3175             :          * Tuple fails this qual.  If it's a required qual for the current
    3176             :          * scan direction, then we can conclude no further tuples will pass,
    3177             :          * either.  Note we have to look at the deciding column, not
    3178             :          * necessarily the first or last column of the row condition.
    3179             :          */
    3180           6 :         if ((subkey->sk_flags & SK_BT_REQFWD) &&
    3181             :             ScanDirectionIsForward(dir))
    3182           6 :             *continuescan = false;
    3183           0 :         else if ((subkey->sk_flags & SK_BT_REQBKWD) &&
    3184             :                  ScanDirectionIsBackward(dir))
    3185           0 :             *continuescan = false;
    3186             :     }
    3187             : 
    3188        2388 :     return result;
    3189             : }
    3190             : 
    3191             : /*
    3192             :  * Determine if a scan with array keys should skip over uninteresting tuples.
    3193             :  *
    3194             :  * This is a subroutine for _bt_checkkeys.  Called when _bt_readpage's linear
    3195             :  * search process (started after it finishes reading an initial group of
    3196             :  * matching tuples, used to locate the start of the next group of tuples
    3197             :  * matching the next set of required array keys) has already scanned an
    3198             :  * excessive number of tuples whose key space is "between arrays".
    3199             :  *
    3200             :  * When we perform look ahead successfully, we'll sets pstate.skip, which
    3201             :  * instructs _bt_readpage to skip ahead to that tuple next (could be past the
    3202             :  * end of the scan's leaf page).  Pages where the optimization is effective
    3203             :  * will generally still need to skip several times.  Each call here performs
    3204             :  * only a single "look ahead" comparison of a later tuple, whose distance from
    3205             :  * the current tuple's offset number is determined by applying heuristics.
    3206             :  */
    3207             : static void
    3208       15404 : _bt_checkkeys_look_ahead(IndexScanDesc scan, BTReadPageState *pstate,
    3209             :                          int tupnatts, TupleDesc tupdesc)
    3210             : {
    3211       15404 :     BTScanOpaque so = (BTScanOpaque) scan->opaque;
    3212       15404 :     ScanDirection dir = so->currPos.dir;
    3213             :     OffsetNumber aheadoffnum;
    3214             :     IndexTuple  ahead;
    3215             : 
    3216             :     Assert(!pstate->forcenonrequired);
    3217             : 
    3218             :     /* Avoid looking ahead when comparing the page high key */
    3219       15404 :     if (pstate->offnum < pstate->minoff)
    3220           0 :         return;
    3221             : 
    3222             :     /*
    3223             :      * Don't look ahead when there aren't enough tuples remaining on the page
    3224             :      * (in the current scan direction) for it to be worth our while
    3225             :      */
    3226       15404 :     if (ScanDirectionIsForward(dir) &&
    3227       15326 :         pstate->offnum >= pstate->maxoff - LOOK_AHEAD_DEFAULT_DISTANCE)
    3228         800 :         return;
    3229       14604 :     else if (ScanDirectionIsBackward(dir) &&
    3230          78 :              pstate->offnum <= pstate->minoff + LOOK_AHEAD_DEFAULT_DISTANCE)
    3231          24 :         return;
    3232             : 
    3233             :     /*
    3234             :      * The look ahead distance starts small, and ramps up as each call here
    3235             :      * allows _bt_readpage to skip over more tuples
    3236             :      */
    3237       14580 :     if (!pstate->targetdistance)
    3238        7978 :         pstate->targetdistance = LOOK_AHEAD_DEFAULT_DISTANCE;
    3239        6602 :     else if (pstate->targetdistance < MaxIndexTuplesPerPage / 2)
    3240        6602 :         pstate->targetdistance *= 2;
    3241             : 
    3242             :     /* Don't read past the end (or before the start) of the page, though */
    3243       14580 :     if (ScanDirectionIsForward(dir))
    3244       14526 :         aheadoffnum = Min((int) pstate->maxoff,
    3245             :                           (int) pstate->offnum + pstate->targetdistance);
    3246             :     else
    3247          54 :         aheadoffnum = Max((int) pstate->minoff,
    3248             :                           (int) pstate->offnum - pstate->targetdistance);
    3249             : 
    3250       14580 :     ahead = (IndexTuple) PageGetItem(pstate->page,
    3251       14580 :                                      PageGetItemId(pstate->page, aheadoffnum));
    3252       14580 :     if (_bt_tuple_before_array_skeys(scan, dir, ahead, tupdesc, tupnatts,
    3253             :                                      false, 0, NULL))
    3254             :     {
    3255             :         /*
    3256             :          * Success -- instruct _bt_readpage to skip ahead to very next tuple
    3257             :          * after the one we determined was still before the current array keys
    3258             :          */
    3259        5178 :         if (ScanDirectionIsForward(dir))
    3260        5142 :             pstate->skip = aheadoffnum + 1;
    3261             :         else
    3262          36 :             pstate->skip = aheadoffnum - 1;
    3263             :     }
    3264             :     else
    3265             :     {
    3266             :         /*
    3267             :          * Failure -- "ahead" tuple is too far ahead (we were too aggressive).
    3268             :          *
    3269             :          * Reset the number of rechecks, and aggressively reduce the target
    3270             :          * distance (we're much more aggressive here than we were when the
    3271             :          * distance was initially ramped up).
    3272             :          */
    3273        9402 :         pstate->rechecks = 0;
    3274        9402 :         pstate->targetdistance = Max(pstate->targetdistance / 8, 1);
    3275             :     }
    3276             : }
    3277             : 
    3278             : /*
    3279             :  * _bt_killitems - set LP_DEAD state for items an indexscan caller has
    3280             :  * told us were killed
    3281             :  *
    3282             :  * scan->opaque, referenced locally through so, contains information about the
    3283             :  * current page and killed tuples thereon (generally, this should only be
    3284             :  * called if so->numKilled > 0).
    3285             :  *
    3286             :  * The caller does not have a lock on the page and may or may not have the
    3287             :  * page pinned in a buffer.  Note that read-lock is sufficient for setting
    3288             :  * LP_DEAD status (which is only a hint).
    3289             :  *
    3290             :  * We match items by heap TID before assuming they are the right ones to
    3291             :  * delete.  We cope with cases where items have moved right due to insertions.
    3292             :  * If an item has moved off the current page due to a split, we'll fail to
    3293             :  * find it and do nothing (this is not an error case --- we assume the item
    3294             :  * will eventually get marked in a future indexscan).
    3295             :  *
    3296             :  * Note that if we hold a pin on the target page continuously from initially
    3297             :  * reading the items until applying this function, VACUUM cannot have deleted
    3298             :  * any items from the page, and so there is no need to search left from the
    3299             :  * recorded offset.  (This observation also guarantees that the item is still
    3300             :  * the right one to delete, which might otherwise be questionable since heap
    3301             :  * TIDs can get recycled.)  This holds true even if the page has been modified
    3302             :  * by inserts and page splits, so there is no need to consult the LSN.
    3303             :  *
    3304             :  * If the pin was released after reading the page, then we re-read it.  If it
    3305             :  * has been modified since we read it (as determined by the LSN), we dare not
    3306             :  * flag any entries because it is possible that the old entry was vacuumed
    3307             :  * away and the TID was re-used by a completely different heap tuple.
    3308             :  */
    3309             : void
    3310      173194 : _bt_killitems(IndexScanDesc scan)
    3311             : {
    3312      173194 :     BTScanOpaque so = (BTScanOpaque) scan->opaque;
    3313             :     Page        page;
    3314             :     BTPageOpaque opaque;
    3315             :     OffsetNumber minoff;
    3316             :     OffsetNumber maxoff;
    3317             :     int         i;
    3318      173194 :     int         numKilled = so->numKilled;
    3319      173194 :     bool        killedsomething = false;
    3320             :     bool        droppedpin PG_USED_FOR_ASSERTS_ONLY;
    3321             : 
    3322             :     Assert(BTScanPosIsValid(so->currPos));
    3323             : 
    3324             :     /*
    3325             :      * Always reset the scan state, so we don't look for same items on other
    3326             :      * pages.
    3327             :      */
    3328      173194 :     so->numKilled = 0;
    3329             : 
    3330      173194 :     if (BTScanPosIsPinned(so->currPos))
    3331             :     {
    3332             :         /*
    3333             :          * We have held the pin on this page since we read the index tuples,
    3334             :          * so all we need to do is lock it.  The pin will have prevented
    3335             :          * re-use of any TID on the page, so there is no need to check the
    3336             :          * LSN.
    3337             :          */
    3338       34688 :         droppedpin = false;
    3339       34688 :         _bt_lockbuf(scan->indexRelation, so->currPos.buf, BT_READ);
    3340             : 
    3341       34688 :         page = BufferGetPage(so->currPos.buf);
    3342             :     }
    3343             :     else
    3344             :     {
    3345             :         Buffer      buf;
    3346             : 
    3347      138506 :         droppedpin = true;
    3348             :         /* Attempt to re-read the buffer, getting pin and lock. */
    3349      138506 :         buf = _bt_getbuf(scan->indexRelation, so->currPos.currPage, BT_READ);
    3350             : 
    3351      138506 :         page = BufferGetPage(buf);
    3352      138506 :         if (BufferGetLSNAtomic(buf) == so->currPos.lsn)
    3353      138390 :             so->currPos.buf = buf;
    3354             :         else
    3355             :         {
    3356             :             /* Modified while not pinned means hinting is not safe. */
    3357         116 :             _bt_relbuf(scan->indexRelation, buf);
    3358         116 :             return;
    3359             :         }
    3360             :     }
    3361             : 
    3362      173078 :     opaque = BTPageGetOpaque(page);
    3363      173078 :     minoff = P_FIRSTDATAKEY(opaque);
    3364      173078 :     maxoff = PageGetMaxOffsetNumber(page);
    3365             : 
    3366      661288 :     for (i = 0; i < numKilled; i++)
    3367             :     {
    3368      488210 :         int         itemIndex = so->killedItems[i];
    3369      488210 :         BTScanPosItem *kitem = &so->currPos.items[itemIndex];
    3370      488210 :         OffsetNumber offnum = kitem->indexOffset;
    3371             : 
    3372             :         Assert(itemIndex >= so->currPos.firstItem &&
    3373             :                itemIndex <= so->currPos.lastItem);
    3374      488210 :         if (offnum < minoff)
    3375           0 :             continue;           /* pure paranoia */
    3376     9411070 :         while (offnum <= maxoff)
    3377             :         {
    3378     9339502 :             ItemId      iid = PageGetItemId(page, offnum);
    3379     9339502 :             IndexTuple  ituple = (IndexTuple) PageGetItem(page, iid);
    3380     9339502 :             bool        killtuple = false;
    3381             : 
    3382     9339502 :             if (BTreeTupleIsPosting(ituple))
    3383             :             {
    3384     2921756 :                 int         pi = i + 1;
    3385     2921756 :                 int         nposting = BTreeTupleGetNPosting(ituple);
    3386             :                 int         j;
    3387             : 
    3388             :                 /*
    3389             :                  * We rely on the convention that heap TIDs in the scanpos
    3390             :                  * items array are stored in ascending heap TID order for a
    3391             :                  * group of TIDs that originally came from a posting list
    3392             :                  * tuple.  This convention even applies during backwards
    3393             :                  * scans, where returning the TIDs in descending order might
    3394             :                  * seem more natural.  This is about effectiveness, not
    3395             :                  * correctness.
    3396             :                  *
    3397             :                  * Note that the page may have been modified in almost any way
    3398             :                  * since we first read it (in the !droppedpin case), so it's
    3399             :                  * possible that this posting list tuple wasn't a posting list
    3400             :                  * tuple when we first encountered its heap TIDs.
    3401             :                  */
    3402     2995170 :                 for (j = 0; j < nposting; j++)
    3403             :                 {
    3404     2992478 :                     ItemPointer item = BTreeTupleGetPostingN(ituple, j);
    3405             : 
    3406     2992478 :                     if (!ItemPointerEquals(item, &kitem->heapTid))
    3407     2919064 :                         break;  /* out of posting list loop */
    3408             : 
    3409             :                     /*
    3410             :                      * kitem must have matching offnum when heap TIDs match,
    3411             :                      * though only in the common case where the page can't
    3412             :                      * have been concurrently modified
    3413             :                      */
    3414             :                     Assert(kitem->indexOffset == offnum || !droppedpin);
    3415             : 
    3416             :                     /*
    3417             :                      * Read-ahead to later kitems here.
    3418             :                      *
    3419             :                      * We rely on the assumption that not advancing kitem here
    3420             :                      * will prevent us from considering the posting list tuple
    3421             :                      * fully dead by not matching its next heap TID in next
    3422             :                      * loop iteration.
    3423             :                      *
    3424             :                      * If, on the other hand, this is the final heap TID in
    3425             :                      * the posting list tuple, then tuple gets killed
    3426             :                      * regardless (i.e. we handle the case where the last
    3427             :                      * kitem is also the last heap TID in the last index tuple
    3428             :                      * correctly -- posting tuple still gets killed).
    3429             :                      */
    3430       73414 :                     if (pi < numKilled)
    3431       37234 :                         kitem = &so->currPos.items[so->killedItems[pi++]];
    3432             :                 }
    3433             : 
    3434             :                 /*
    3435             :                  * Don't bother advancing the outermost loop's int iterator to
    3436             :                  * avoid processing killed items that relate to the same
    3437             :                  * offnum/posting list tuple.  This micro-optimization hardly
    3438             :                  * seems worth it.  (Further iterations of the outermost loop
    3439             :                  * will fail to match on this same posting list's first heap
    3440             :                  * TID instead, so we'll advance to the next offnum/index
    3441             :                  * tuple pretty quickly.)
    3442             :                  */
    3443     2921756 :                 if (j == nposting)
    3444        2692 :                     killtuple = true;
    3445             :             }
    3446     6417746 :             else if (ItemPointerEquals(&ituple->t_tid, &kitem->heapTid))
    3447      415270 :                 killtuple = true;
    3448             : 
    3449             :             /*
    3450             :              * Mark index item as dead, if it isn't already.  Since this
    3451             :              * happens while holding a buffer lock possibly in shared mode,
    3452             :              * it's possible that multiple processes attempt to do this
    3453             :              * simultaneously, leading to multiple full-page images being sent
    3454             :              * to WAL (if wal_log_hints or data checksums are enabled), which
    3455             :              * is undesirable.
    3456             :              */
    3457     9339502 :             if (killtuple && !ItemIdIsDead(iid))
    3458             :             {
    3459             :                 /* found the item/all posting list items */
    3460      416642 :                 ItemIdMarkDead(iid);
    3461      416642 :                 killedsomething = true;
    3462      416642 :                 break;          /* out of inner search loop */
    3463             :             }
    3464     8922860 :             offnum = OffsetNumberNext(offnum);
    3465             :         }
    3466             :     }
    3467             : 
    3468             :     /*
    3469             :      * Since this can be redone later if needed, mark as dirty hint.
    3470             :      *
    3471             :      * Whenever we mark anything LP_DEAD, we also set the page's
    3472             :      * BTP_HAS_GARBAGE flag, which is likewise just a hint.  (Note that we
    3473             :      * only rely on the page-level flag in !heapkeyspace indexes.)
    3474             :      */
    3475      173078 :     if (killedsomething)
    3476             :     {
    3477      135592 :         opaque->btpo_flags |= BTP_HAS_GARBAGE;
    3478      135592 :         MarkBufferDirtyHint(so->currPos.buf, true);
    3479             :     }
    3480             : 
    3481      173078 :     _bt_unlockbuf(scan->indexRelation, so->currPos.buf);
    3482             : }
    3483             : 
    3484             : 
    3485             : /*
    3486             :  * The following routines manage a shared-memory area in which we track
    3487             :  * assignment of "vacuum cycle IDs" to currently-active btree vacuuming
    3488             :  * operations.  There is a single counter which increments each time we
    3489             :  * start a vacuum to assign it a cycle ID.  Since multiple vacuums could
    3490             :  * be active concurrently, we have to track the cycle ID for each active
    3491             :  * vacuum; this requires at most MaxBackends entries (usually far fewer).
    3492             :  * We assume at most one vacuum can be active for a given index.
    3493             :  *
    3494             :  * Access to the shared memory area is controlled by BtreeVacuumLock.
    3495             :  * In principle we could use a separate lmgr locktag for each index,
    3496             :  * but a single LWLock is much cheaper, and given the short time that
    3497             :  * the lock is ever held, the concurrency hit should be minimal.
    3498             :  */
    3499             : 
    3500             : typedef struct BTOneVacInfo
    3501             : {
    3502             :     LockRelId   relid;          /* global identifier of an index */
    3503             :     BTCycleId   cycleid;        /* cycle ID for its active VACUUM */
    3504             : } BTOneVacInfo;
    3505             : 
    3506             : typedef struct BTVacInfo
    3507             : {
    3508             :     BTCycleId   cycle_ctr;      /* cycle ID most recently assigned */
    3509             :     int         num_vacuums;    /* number of currently active VACUUMs */
    3510             :     int         max_vacuums;    /* allocated length of vacuums[] array */
    3511             :     BTOneVacInfo vacuums[FLEXIBLE_ARRAY_MEMBER];
    3512             : } BTVacInfo;
    3513             : 
    3514             : static BTVacInfo *btvacinfo;
    3515             : 
    3516             : 
    3517             : /*
    3518             :  * _bt_vacuum_cycleid --- get the active vacuum cycle ID for an index,
    3519             :  *      or zero if there is no active VACUUM
    3520             :  *
    3521             :  * Note: for correct interlocking, the caller must already hold pin and
    3522             :  * exclusive lock on each buffer it will store the cycle ID into.  This
    3523             :  * ensures that even if a VACUUM starts immediately afterwards, it cannot
    3524             :  * process those pages until the page split is complete.
    3525             :  */
    3526             : BTCycleId
    3527       22522 : _bt_vacuum_cycleid(Relation rel)
    3528             : {
    3529       22522 :     BTCycleId   result = 0;
    3530             :     int         i;
    3531             : 
    3532             :     /* Share lock is enough since this is a read-only operation */
    3533       22522 :     LWLockAcquire(BtreeVacuumLock, LW_SHARED);
    3534             : 
    3535       22522 :     for (i = 0; i < btvacinfo->num_vacuums; i++)
    3536             :     {
    3537           0 :         BTOneVacInfo *vac = &btvacinfo->vacuums[i];
    3538             : 
    3539           0 :         if (vac->relid.relId == rel->rd_lockInfo.lockRelId.relId &&
    3540           0 :             vac->relid.dbId == rel->rd_lockInfo.lockRelId.dbId)
    3541             :         {
    3542           0 :             result = vac->cycleid;
    3543           0 :             break;
    3544             :         }
    3545             :     }
    3546             : 
    3547       22522 :     LWLockRelease(BtreeVacuumLock);
    3548       22522 :     return result;
    3549             : }
    3550             : 
    3551             : /*
    3552             :  * _bt_start_vacuum --- assign a cycle ID to a just-starting VACUUM operation
    3553             :  *
    3554             :  * Note: the caller must guarantee that it will eventually call
    3555             :  * _bt_end_vacuum, else we'll permanently leak an array slot.  To ensure
    3556             :  * that this happens even in elog(FATAL) scenarios, the appropriate coding
    3557             :  * is not just a PG_TRY, but
    3558             :  *      PG_ENSURE_ERROR_CLEANUP(_bt_end_vacuum_callback, PointerGetDatum(rel))
    3559             :  */
    3560             : BTCycleId
    3561        2774 : _bt_start_vacuum(Relation rel)
    3562             : {
    3563             :     BTCycleId   result;
    3564             :     int         i;
    3565             :     BTOneVacInfo *vac;
    3566             : 
    3567        2774 :     LWLockAcquire(BtreeVacuumLock, LW_EXCLUSIVE);
    3568             : 
    3569             :     /*
    3570             :      * Assign the next cycle ID, being careful to avoid zero as well as the
    3571             :      * reserved high values.
    3572             :      */
    3573        2774 :     result = ++(btvacinfo->cycle_ctr);
    3574        2774 :     if (result == 0 || result > MAX_BT_CYCLE_ID)
    3575           0 :         result = btvacinfo->cycle_ctr = 1;
    3576             : 
    3577             :     /* Let's just make sure there's no entry already for this index */
    3578        2774 :     for (i = 0; i < btvacinfo->num_vacuums; i++)
    3579             :     {
    3580           0 :         vac = &btvacinfo->vacuums[i];
    3581           0 :         if (vac->relid.relId == rel->rd_lockInfo.lockRelId.relId &&
    3582           0 :             vac->relid.dbId == rel->rd_lockInfo.lockRelId.dbId)
    3583             :         {
    3584             :             /*
    3585             :              * Unlike most places in the backend, we have to explicitly
    3586             :              * release our LWLock before throwing an error.  This is because
    3587             :              * we expect _bt_end_vacuum() to be called before transaction
    3588             :              * abort cleanup can run to release LWLocks.
    3589             :              */
    3590           0 :             LWLockRelease(BtreeVacuumLock);
    3591           0 :             elog(ERROR, "multiple active vacuums for index \"%s\"",
    3592             :                  RelationGetRelationName(rel));
    3593             :         }
    3594             :     }
    3595             : 
    3596             :     /* OK, add an entry */
    3597        2774 :     if (btvacinfo->num_vacuums >= btvacinfo->max_vacuums)
    3598             :     {
    3599           0 :         LWLockRelease(BtreeVacuumLock);
    3600           0 :         elog(ERROR, "out of btvacinfo slots");
    3601             :     }
    3602        2774 :     vac = &btvacinfo->vacuums[btvacinfo->num_vacuums];
    3603        2774 :     vac->relid = rel->rd_lockInfo.lockRelId;
    3604        2774 :     vac->cycleid = result;
    3605        2774 :     btvacinfo->num_vacuums++;
    3606             : 
    3607        2774 :     LWLockRelease(BtreeVacuumLock);
    3608        2774 :     return result;
    3609             : }
    3610             : 
    3611             : /*
    3612             :  * _bt_end_vacuum --- mark a btree VACUUM operation as done
    3613             :  *
    3614             :  * Note: this is deliberately coded not to complain if no entry is found;
    3615             :  * this allows the caller to put PG_TRY around the start_vacuum operation.
    3616             :  */
    3617             : void
    3618        2774 : _bt_end_vacuum(Relation rel)
    3619             : {
    3620             :     int         i;
    3621             : 
    3622        2774 :     LWLockAcquire(BtreeVacuumLock, LW_EXCLUSIVE);
    3623             : 
    3624             :     /* Find the array entry */
    3625        2774 :     for (i = 0; i < btvacinfo->num_vacuums; i++)
    3626             :     {
    3627        2774 :         BTOneVacInfo *vac = &btvacinfo->vacuums[i];
    3628             : 
    3629        2774 :         if (vac->relid.relId == rel->rd_lockInfo.lockRelId.relId &&
    3630        2774 :             vac->relid.dbId == rel->rd_lockInfo.lockRelId.dbId)
    3631             :         {
    3632             :             /* Remove it by shifting down the last entry */
    3633        2774 :             *vac = btvacinfo->vacuums[btvacinfo->num_vacuums - 1];
    3634        2774 :             btvacinfo->num_vacuums--;
    3635        2774 :             break;
    3636             :         }
    3637             :     }
    3638             : 
    3639        2774 :     LWLockRelease(BtreeVacuumLock);
    3640        2774 : }
    3641             : 
    3642             : /*
    3643             :  * _bt_end_vacuum wrapped as an on_shmem_exit callback function
    3644             :  */
    3645             : void
    3646           0 : _bt_end_vacuum_callback(int code, Datum arg)
    3647             : {
    3648           0 :     _bt_end_vacuum((Relation) DatumGetPointer(arg));
    3649           0 : }
    3650             : 
    3651             : /*
    3652             :  * BTreeShmemSize --- report amount of shared memory space needed
    3653             :  */
    3654             : Size
    3655        5994 : BTreeShmemSize(void)
    3656             : {
    3657             :     Size        size;
    3658             : 
    3659        5994 :     size = offsetof(BTVacInfo, vacuums);
    3660        5994 :     size = add_size(size, mul_size(MaxBackends, sizeof(BTOneVacInfo)));
    3661        5994 :     return size;
    3662             : }
    3663             : 
    3664             : /*
    3665             :  * BTreeShmemInit --- initialize this module's shared memory
    3666             :  */
    3667             : void
    3668        2096 : BTreeShmemInit(void)
    3669             : {
    3670             :     bool        found;
    3671             : 
    3672        2096 :     btvacinfo = (BTVacInfo *) ShmemInitStruct("BTree Vacuum State",
    3673             :                                               BTreeShmemSize(),
    3674             :                                               &found);
    3675             : 
    3676        2096 :     if (!IsUnderPostmaster)
    3677             :     {
    3678             :         /* Initialize shared memory area */
    3679             :         Assert(!found);
    3680             : 
    3681             :         /*
    3682             :          * It doesn't really matter what the cycle counter starts at, but
    3683             :          * having it always start the same doesn't seem good.  Seed with
    3684             :          * low-order bits of time() instead.
    3685             :          */
    3686        2096 :         btvacinfo->cycle_ctr = (BTCycleId) time(NULL);
    3687             : 
    3688        2096 :         btvacinfo->num_vacuums = 0;
    3689        2096 :         btvacinfo->max_vacuums = MaxBackends;
    3690             :     }
    3691             :     else
    3692             :         Assert(found);
    3693        2096 : }
    3694             : 
    3695             : bytea *
    3696         362 : btoptions(Datum reloptions, bool validate)
    3697             : {
    3698             :     static const relopt_parse_elt tab[] = {
    3699             :         {"fillfactor", RELOPT_TYPE_INT, offsetof(BTOptions, fillfactor)},
    3700             :         {"vacuum_cleanup_index_scale_factor", RELOPT_TYPE_REAL,
    3701             :         offsetof(BTOptions, vacuum_cleanup_index_scale_factor)},
    3702             :         {"deduplicate_items", RELOPT_TYPE_BOOL,
    3703             :         offsetof(BTOptions, deduplicate_items)}
    3704             :     };
    3705             : 
    3706         362 :     return (bytea *) build_reloptions(reloptions, validate,
    3707             :                                       RELOPT_KIND_BTREE,
    3708             :                                       sizeof(BTOptions),
    3709             :                                       tab, lengthof(tab));
    3710             : }
    3711             : 
    3712             : /*
    3713             :  *  btproperty() -- Check boolean properties of indexes.
    3714             :  *
    3715             :  * This is optional, but handling AMPROP_RETURNABLE here saves opening the rel
    3716             :  * to call btcanreturn.
    3717             :  */
    3718             : bool
    3719         756 : btproperty(Oid index_oid, int attno,
    3720             :            IndexAMProperty prop, const char *propname,
    3721             :            bool *res, bool *isnull)
    3722             : {
    3723         756 :     switch (prop)
    3724             :     {
    3725          42 :         case AMPROP_RETURNABLE:
    3726             :             /* answer only for columns, not AM or whole index */
    3727          42 :             if (attno == 0)
    3728          12 :                 return false;
    3729             :             /* otherwise, btree can always return data */
    3730          30 :             *res = true;
    3731          30 :             return true;
    3732             : 
    3733         714 :         default:
    3734         714 :             return false;       /* punt to generic code */
    3735             :     }
    3736             : }
    3737             : 
    3738             : /*
    3739             :  *  btbuildphasename() -- Return name of index build phase.
    3740             :  */
    3741             : char *
    3742           0 : btbuildphasename(int64 phasenum)
    3743             : {
    3744           0 :     switch (phasenum)
    3745             :     {
    3746           0 :         case PROGRESS_CREATEIDX_SUBPHASE_INITIALIZE:
    3747           0 :             return "initializing";
    3748           0 :         case PROGRESS_BTREE_PHASE_INDEXBUILD_TABLESCAN:
    3749           0 :             return "scanning table";
    3750           0 :         case PROGRESS_BTREE_PHASE_PERFORMSORT_1:
    3751           0 :             return "sorting live tuples";
    3752           0 :         case PROGRESS_BTREE_PHASE_PERFORMSORT_2:
    3753           0 :             return "sorting dead tuples";
    3754           0 :         case PROGRESS_BTREE_PHASE_LEAF_LOAD:
    3755           0 :             return "loading tuples in tree";
    3756           0 :         default:
    3757           0 :             return NULL;
    3758             :     }
    3759             : }
    3760             : 
    3761             : /*
    3762             :  *  _bt_truncate() -- create tuple without unneeded suffix attributes.
    3763             :  *
    3764             :  * Returns truncated pivot index tuple allocated in caller's memory context,
    3765             :  * with key attributes copied from caller's firstright argument.  If rel is
    3766             :  * an INCLUDE index, non-key attributes will definitely be truncated away,
    3767             :  * since they're not part of the key space.  More aggressive suffix
    3768             :  * truncation can take place when it's clear that the returned tuple does not
    3769             :  * need one or more suffix key attributes.  We only need to keep firstright
    3770             :  * attributes up to and including the first non-lastleft-equal attribute.
    3771             :  * Caller's insertion scankey is used to compare the tuples; the scankey's
    3772             :  * argument values are not considered here.
    3773             :  *
    3774             :  * Note that returned tuple's t_tid offset will hold the number of attributes
    3775             :  * present, so the original item pointer offset is not represented.  Caller
    3776             :  * should only change truncated tuple's downlink.  Note also that truncated
    3777             :  * key attributes are treated as containing "minus infinity" values by
    3778             :  * _bt_compare().
    3779             :  *
    3780             :  * In the worst case (when a heap TID must be appended to distinguish lastleft
    3781             :  * from firstright), the size of the returned tuple is the size of firstright
    3782             :  * plus the size of an additional MAXALIGN()'d item pointer.  This guarantee
    3783             :  * is important, since callers need to stay under the 1/3 of a page
    3784             :  * restriction on tuple size.  If this routine is ever taught to truncate
    3785             :  * within an attribute/datum, it will need to avoid returning an enlarged
    3786             :  * tuple to caller when truncation + TOAST compression ends up enlarging the
    3787             :  * final datum.
    3788             :  */
    3789             : IndexTuple
    3790       63274 : _bt_truncate(Relation rel, IndexTuple lastleft, IndexTuple firstright,
    3791             :              BTScanInsert itup_key)
    3792             : {
    3793       63274 :     TupleDesc   itupdesc = RelationGetDescr(rel);
    3794       63274 :     int16       nkeyatts = IndexRelationGetNumberOfKeyAttributes(rel);
    3795             :     int         keepnatts;
    3796             :     IndexTuple  pivot;
    3797             :     IndexTuple  tidpivot;
    3798             :     ItemPointer pivotheaptid;
    3799             :     Size        newsize;
    3800             : 
    3801             :     /*
    3802             :      * We should only ever truncate non-pivot tuples from leaf pages.  It's
    3803             :      * never okay to truncate when splitting an internal page.
    3804             :      */
    3805             :     Assert(!BTreeTupleIsPivot(lastleft) && !BTreeTupleIsPivot(firstright));
    3806             : 
    3807             :     /* Determine how many attributes must be kept in truncated tuple */
    3808       63274 :     keepnatts = _bt_keep_natts(rel, lastleft, firstright, itup_key);
    3809             : 
    3810             : #ifdef DEBUG_NO_TRUNCATE
    3811             :     /* Force truncation to be ineffective for testing purposes */
    3812             :     keepnatts = nkeyatts + 1;
    3813             : #endif
    3814             : 
    3815       63274 :     pivot = index_truncate_tuple(itupdesc, firstright,
    3816             :                                  Min(keepnatts, nkeyatts));
    3817             : 
    3818       63274 :     if (BTreeTupleIsPosting(pivot))
    3819             :     {
    3820             :         /*
    3821             :          * index_truncate_tuple() just returns a straight copy of firstright
    3822             :          * when it has no attributes to truncate.  When that happens, we may
    3823             :          * need to truncate away a posting list here instead.
    3824             :          */
    3825             :         Assert(keepnatts == nkeyatts || keepnatts == nkeyatts + 1);
    3826             :         Assert(IndexRelationGetNumberOfAttributes(rel) == nkeyatts);
    3827        1290 :         pivot->t_info &= ~INDEX_SIZE_MASK;
    3828        1290 :         pivot->t_info |= MAXALIGN(BTreeTupleGetPostingOffset(firstright));
    3829             :     }
    3830             : 
    3831             :     /*
    3832             :      * If there is a distinguishing key attribute within pivot tuple, we're
    3833             :      * done
    3834             :      */
    3835       63274 :     if (keepnatts <= nkeyatts)
    3836             :     {
    3837       62118 :         BTreeTupleSetNAtts(pivot, keepnatts, false);
    3838       62118 :         return pivot;
    3839             :     }
    3840             : 
    3841             :     /*
    3842             :      * We have to store a heap TID in the new pivot tuple, since no non-TID
    3843             :      * key attribute value in firstright distinguishes the right side of the
    3844             :      * split from the left side.  nbtree conceptualizes this case as an
    3845             :      * inability to truncate away any key attributes, since heap TID is
    3846             :      * treated as just another key attribute (despite lacking a pg_attribute
    3847             :      * entry).
    3848             :      *
    3849             :      * Use enlarged space that holds a copy of pivot.  We need the extra space
    3850             :      * to store a heap TID at the end (using the special pivot tuple
    3851             :      * representation).  Note that the original pivot already has firstright's
    3852             :      * possible posting list/non-key attribute values removed at this point.
    3853             :      */
    3854        1156 :     newsize = MAXALIGN(IndexTupleSize(pivot)) + MAXALIGN(sizeof(ItemPointerData));
    3855        1156 :     tidpivot = palloc0(newsize);
    3856        1156 :     memcpy(tidpivot, pivot, MAXALIGN(IndexTupleSize(pivot)));
    3857             :     /* Cannot leak memory here */
    3858        1156 :     pfree(pivot);
    3859             : 
    3860             :     /*
    3861             :      * Store all of firstright's key attribute values plus a tiebreaker heap
    3862             :      * TID value in enlarged pivot tuple
    3863             :      */
    3864        1156 :     tidpivot->t_info &= ~INDEX_SIZE_MASK;
    3865        1156 :     tidpivot->t_info |= newsize;
    3866        1156 :     BTreeTupleSetNAtts(tidpivot, nkeyatts, true);
    3867        1156 :     pivotheaptid = BTreeTupleGetHeapTID(tidpivot);
    3868             : 
    3869             :     /*
    3870             :      * Lehman & Yao use lastleft as the leaf high key in all cases, but don't
    3871             :      * consider suffix truncation.  It seems like a good idea to follow that
    3872             :      * example in cases where no truncation takes place -- use lastleft's heap
    3873             :      * TID.  (This is also the closest value to negative infinity that's
    3874             :      * legally usable.)
    3875             :      */
    3876        1156 :     ItemPointerCopy(BTreeTupleGetMaxHeapTID(lastleft), pivotheaptid);
    3877             : 
    3878             :     /*
    3879             :      * We're done.  Assert() that heap TID invariants hold before returning.
    3880             :      *
    3881             :      * Lehman and Yao require that the downlink to the right page, which is to
    3882             :      * be inserted into the parent page in the second phase of a page split be
    3883             :      * a strict lower bound on items on the right page, and a non-strict upper
    3884             :      * bound for items on the left page.  Assert that heap TIDs follow these
    3885             :      * invariants, since a heap TID value is apparently needed as a
    3886             :      * tiebreaker.
    3887             :      */
    3888             : #ifndef DEBUG_NO_TRUNCATE
    3889             :     Assert(ItemPointerCompare(BTreeTupleGetMaxHeapTID(lastleft),
    3890             :                               BTreeTupleGetHeapTID(firstright)) < 0);
    3891             :     Assert(ItemPointerCompare(pivotheaptid,
    3892             :                               BTreeTupleGetHeapTID(lastleft)) >= 0);
    3893             :     Assert(ItemPointerCompare(pivotheaptid,
    3894             :                               BTreeTupleGetHeapTID(firstright)) < 0);
    3895             : #else
    3896             : 
    3897             :     /*
    3898             :      * Those invariants aren't guaranteed to hold for lastleft + firstright
    3899             :      * heap TID attribute values when they're considered here only because
    3900             :      * DEBUG_NO_TRUNCATE is defined (a heap TID is probably not actually
    3901             :      * needed as a tiebreaker).  DEBUG_NO_TRUNCATE must therefore use a heap
    3902             :      * TID value that always works as a strict lower bound for items to the
    3903             :      * right.  In particular, it must avoid using firstright's leading key
    3904             :      * attribute values along with lastleft's heap TID value when lastleft's
    3905             :      * TID happens to be greater than firstright's TID.
    3906             :      */
    3907             :     ItemPointerCopy(BTreeTupleGetHeapTID(firstright), pivotheaptid);
    3908             : 
    3909             :     /*
    3910             :      * Pivot heap TID should never be fully equal to firstright.  Note that
    3911             :      * the pivot heap TID will still end up equal to lastleft's heap TID when
    3912             :      * that's the only usable value.
    3913             :      */
    3914             :     ItemPointerSetOffsetNumber(pivotheaptid,
    3915             :                                OffsetNumberPrev(ItemPointerGetOffsetNumber(pivotheaptid)));
    3916             :     Assert(ItemPointerCompare(pivotheaptid,
    3917             :                               BTreeTupleGetHeapTID(firstright)) < 0);
    3918             : #endif
    3919             : 
    3920        1156 :     return tidpivot;
    3921             : }
    3922             : 
    3923             : /*
    3924             :  * _bt_keep_natts - how many key attributes to keep when truncating.
    3925             :  *
    3926             :  * Caller provides two tuples that enclose a split point.  Caller's insertion
    3927             :  * scankey is used to compare the tuples; the scankey's argument values are
    3928             :  * not considered here.
    3929             :  *
    3930             :  * This can return a number of attributes that is one greater than the
    3931             :  * number of key attributes for the index relation.  This indicates that the
    3932             :  * caller must use a heap TID as a unique-ifier in new pivot tuple.
    3933             :  */
    3934             : static int
    3935       63274 : _bt_keep_natts(Relation rel, IndexTuple lastleft, IndexTuple firstright,
    3936             :                BTScanInsert itup_key)
    3937             : {
    3938       63274 :     int         nkeyatts = IndexRelationGetNumberOfKeyAttributes(rel);
    3939       63274 :     TupleDesc   itupdesc = RelationGetDescr(rel);
    3940             :     int         keepnatts;
    3941             :     ScanKey     scankey;
    3942             : 
    3943             :     /*
    3944             :      * _bt_compare() treats truncated key attributes as having the value minus
    3945             :      * infinity, which would break searches within !heapkeyspace indexes.  We
    3946             :      * must still truncate away non-key attribute values, though.
    3947             :      */
    3948       63274 :     if (!itup_key->heapkeyspace)
    3949           0 :         return nkeyatts;
    3950             : 
    3951       63274 :     scankey = itup_key->scankeys;
    3952       63274 :     keepnatts = 1;
    3953       76860 :     for (int attnum = 1; attnum <= nkeyatts; attnum++, scankey++)
    3954             :     {
    3955             :         Datum       datum1,
    3956             :                     datum2;
    3957             :         bool        isNull1,
    3958             :                     isNull2;
    3959             : 
    3960       75704 :         datum1 = index_getattr(lastleft, attnum, itupdesc, &isNull1);
    3961       75704 :         datum2 = index_getattr(firstright, attnum, itupdesc, &isNull2);
    3962             : 
    3963       75704 :         if (isNull1 != isNull2)
    3964       62118 :             break;
    3965             : 
    3966      151376 :         if (!isNull1 &&
    3967       75672 :             DatumGetInt32(FunctionCall2Coll(&scankey->sk_func,
    3968             :                                             scankey->sk_collation,
    3969             :                                             datum1,
    3970             :                                             datum2)) != 0)
    3971       62118 :             break;
    3972             : 
    3973       13586 :         keepnatts++;
    3974             :     }
    3975             : 
    3976             :     /*
    3977             :      * Assert that _bt_keep_natts_fast() agrees with us in passing.  This is
    3978             :      * expected in an allequalimage index.
    3979             :      */
    3980             :     Assert(!itup_key->allequalimage ||
    3981             :            keepnatts == _bt_keep_natts_fast(rel, lastleft, firstright));
    3982             : 
    3983       63274 :     return keepnatts;
    3984             : }
    3985             : 
    3986             : /*
    3987             :  * _bt_keep_natts_fast - fast bitwise variant of _bt_keep_natts.
    3988             :  *
    3989             :  * This is exported so that a candidate split point can have its effect on
    3990             :  * suffix truncation inexpensively evaluated ahead of time when finding a
    3991             :  * split location.  A naive bitwise approach to datum comparisons is used to
    3992             :  * save cycles.
    3993             :  *
    3994             :  * The approach taken here usually provides the same answer as _bt_keep_natts
    3995             :  * will (for the same pair of tuples from a heapkeyspace index), since the
    3996             :  * majority of btree opclasses can never indicate that two datums are equal
    3997             :  * unless they're bitwise equal after detoasting.  When an index only has
    3998             :  * "equal image" columns, routine is guaranteed to give the same result as
    3999             :  * _bt_keep_natts would.
    4000             :  *
    4001             :  * Callers can rely on the fact that attributes considered equal here are
    4002             :  * definitely also equal according to _bt_keep_natts, even when the index uses
    4003             :  * an opclass or collation that is not "allequalimage"/deduplication-safe.
    4004             :  * This weaker guarantee is good enough for nbtsplitloc.c caller, since false
    4005             :  * negatives generally only have the effect of making leaf page splits use a
    4006             :  * more balanced split point.
    4007             :  */
    4008             : int
    4009    13827282 : _bt_keep_natts_fast(Relation rel, IndexTuple lastleft, IndexTuple firstright)
    4010             : {
    4011    13827282 :     TupleDesc   itupdesc = RelationGetDescr(rel);
    4012    13827282 :     int         keysz = IndexRelationGetNumberOfKeyAttributes(rel);
    4013             :     int         keepnatts;
    4014             : 
    4015    13827282 :     keepnatts = 1;
    4016    23141368 :     for (int attnum = 1; attnum <= keysz; attnum++)
    4017             :     {
    4018             :         Datum       datum1,
    4019             :                     datum2;
    4020             :         bool        isNull1,
    4021             :                     isNull2;
    4022             :         CompactAttribute *att;
    4023             : 
    4024    20698354 :         datum1 = index_getattr(lastleft, attnum, itupdesc, &isNull1);
    4025    20698354 :         datum2 = index_getattr(firstright, attnum, itupdesc, &isNull2);
    4026    20698354 :         att = TupleDescCompactAttr(itupdesc, attnum - 1);
    4027             : 
    4028    20698354 :         if (isNull1 != isNull2)
    4029    11384268 :             break;
    4030             : 
    4031    20698148 :         if (!isNull1 &&
    4032    20651072 :             !datum_image_eq(datum1, datum2, att->attbyval, att->attlen))
    4033    11384062 :             break;
    4034             : 
    4035     9314086 :         keepnatts++;
    4036             :     }
    4037             : 
    4038    13827282 :     return keepnatts;
    4039             : }
    4040             : 
    4041             : /*
    4042             :  *  _bt_check_natts() -- Verify tuple has expected number of attributes.
    4043             :  *
    4044             :  * Returns value indicating if the expected number of attributes were found
    4045             :  * for a particular offset on page.  This can be used as a general purpose
    4046             :  * sanity check.
    4047             :  *
    4048             :  * Testing a tuple directly with BTreeTupleGetNAtts() should generally be
    4049             :  * preferred to calling here.  That's usually more convenient, and is always
    4050             :  * more explicit.  Call here instead when offnum's tuple may be a negative
    4051             :  * infinity tuple that uses the pre-v11 on-disk representation, or when a low
    4052             :  * context check is appropriate.  This routine is as strict as possible about
    4053             :  * what is expected on each version of btree.
    4054             :  */
    4055             : bool
    4056     4053222 : _bt_check_natts(Relation rel, bool heapkeyspace, Page page, OffsetNumber offnum)
    4057             : {
    4058     4053222 :     int16       natts = IndexRelationGetNumberOfAttributes(rel);
    4059     4053222 :     int16       nkeyatts = IndexRelationGetNumberOfKeyAttributes(rel);
    4060     4053222 :     BTPageOpaque opaque = BTPageGetOpaque(page);
    4061             :     IndexTuple  itup;
    4062             :     int         tupnatts;
    4063             : 
    4064             :     /*
    4065             :      * We cannot reliably test a deleted or half-dead page, since they have
    4066             :      * dummy high keys
    4067             :      */
    4068     4053222 :     if (P_IGNORE(opaque))
    4069           0 :         return true;
    4070             : 
    4071             :     Assert(offnum >= FirstOffsetNumber &&
    4072             :            offnum <= PageGetMaxOffsetNumber(page));
    4073             : 
    4074     4053222 :     itup = (IndexTuple) PageGetItem(page, PageGetItemId(page, offnum));
    4075     4053222 :     tupnatts = BTreeTupleGetNAtts(itup, rel);
    4076             : 
    4077             :     /* !heapkeyspace indexes do not support deduplication */
    4078     4053222 :     if (!heapkeyspace && BTreeTupleIsPosting(itup))
    4079           0 :         return false;
    4080             : 
    4081             :     /* Posting list tuples should never have "pivot heap TID" bit set */
    4082     4053222 :     if (BTreeTupleIsPosting(itup) &&
    4083       21906 :         (ItemPointerGetOffsetNumberNoCheck(&itup->t_tid) &
    4084             :          BT_PIVOT_HEAP_TID_ATTR) != 0)
    4085           0 :         return false;
    4086             : 
    4087             :     /* INCLUDE indexes do not support deduplication */
    4088     4053222 :     if (natts != nkeyatts && BTreeTupleIsPosting(itup))
    4089           0 :         return false;
    4090             : 
    4091     4053222 :     if (P_ISLEAF(opaque))
    4092             :     {
    4093     4038870 :         if (offnum >= P_FIRSTDATAKEY(opaque))
    4094             :         {
    4095             :             /*
    4096             :              * Non-pivot tuple should never be explicitly marked as a pivot
    4097             :              * tuple
    4098             :              */
    4099     4025638 :             if (BTreeTupleIsPivot(itup))
    4100           0 :                 return false;
    4101             : 
    4102             :             /*
    4103             :              * Leaf tuples that are not the page high key (non-pivot tuples)
    4104             :              * should never be truncated.  (Note that tupnatts must have been
    4105             :              * inferred, even with a posting list tuple, because only pivot
    4106             :              * tuples store tupnatts directly.)
    4107             :              */
    4108     4025638 :             return tupnatts == natts;
    4109             :         }
    4110             :         else
    4111             :         {
    4112             :             /*
    4113             :              * Rightmost page doesn't contain a page high key, so tuple was
    4114             :              * checked above as ordinary leaf tuple
    4115             :              */
    4116             :             Assert(!P_RIGHTMOST(opaque));
    4117             : 
    4118             :             /*
    4119             :              * !heapkeyspace high key tuple contains only key attributes. Note
    4120             :              * that tupnatts will only have been explicitly represented in
    4121             :              * !heapkeyspace indexes that happen to have non-key attributes.
    4122             :              */
    4123       13232 :             if (!heapkeyspace)
    4124           0 :                 return tupnatts == nkeyatts;
    4125             : 
    4126             :             /* Use generic heapkeyspace pivot tuple handling */
    4127             :         }
    4128             :     }
    4129             :     else                        /* !P_ISLEAF(opaque) */
    4130             :     {
    4131       14352 :         if (offnum == P_FIRSTDATAKEY(opaque))
    4132             :         {
    4133             :             /*
    4134             :              * The first tuple on any internal page (possibly the first after
    4135             :              * its high key) is its negative infinity tuple.  Negative
    4136             :              * infinity tuples are always truncated to zero attributes.  They
    4137             :              * are a particular kind of pivot tuple.
    4138             :              */
    4139        1114 :             if (heapkeyspace)
    4140        1114 :                 return tupnatts == 0;
    4141             : 
    4142             :             /*
    4143             :              * The number of attributes won't be explicitly represented if the
    4144             :              * negative infinity tuple was generated during a page split that
    4145             :              * occurred with a version of Postgres before v11.  There must be
    4146             :              * a problem when there is an explicit representation that is
    4147             :              * non-zero, or when there is no explicit representation and the
    4148             :              * tuple is evidently not a pre-pg_upgrade tuple.
    4149             :              *
    4150             :              * Prior to v11, downlinks always had P_HIKEY as their offset.
    4151             :              * Accept that as an alternative indication of a valid
    4152             :              * !heapkeyspace negative infinity tuple.
    4153             :              */
    4154           0 :             return tupnatts == 0 ||
    4155           0 :                 ItemPointerGetOffsetNumber(&(itup->t_tid)) == P_HIKEY;
    4156             :         }
    4157             :         else
    4158             :         {
    4159             :             /*
    4160             :              * !heapkeyspace downlink tuple with separator key contains only
    4161             :              * key attributes.  Note that tupnatts will only have been
    4162             :              * explicitly represented in !heapkeyspace indexes that happen to
    4163             :              * have non-key attributes.
    4164             :              */
    4165       13238 :             if (!heapkeyspace)
    4166           0 :                 return tupnatts == nkeyatts;
    4167             : 
    4168             :             /* Use generic heapkeyspace pivot tuple handling */
    4169             :         }
    4170             :     }
    4171             : 
    4172             :     /* Handle heapkeyspace pivot tuples (excluding minus infinity items) */
    4173             :     Assert(heapkeyspace);
    4174             : 
    4175             :     /*
    4176             :      * Explicit representation of the number of attributes is mandatory with
    4177             :      * heapkeyspace index pivot tuples, regardless of whether or not there are
    4178             :      * non-key attributes.
    4179             :      */
    4180       26470 :     if (!BTreeTupleIsPivot(itup))
    4181           0 :         return false;
    4182             : 
    4183             :     /* Pivot tuple should not use posting list representation (redundant) */
    4184       26470 :     if (BTreeTupleIsPosting(itup))
    4185           0 :         return false;
    4186             : 
    4187             :     /*
    4188             :      * Heap TID is a tiebreaker key attribute, so it cannot be untruncated
    4189             :      * when any other key attribute is truncated
    4190             :      */
    4191       26470 :     if (BTreeTupleGetHeapTID(itup) != NULL && tupnatts != nkeyatts)
    4192           0 :         return false;
    4193             : 
    4194             :     /*
    4195             :      * Pivot tuple must have at least one untruncated key attribute (minus
    4196             :      * infinity pivot tuples are the only exception).  Pivot tuples can never
    4197             :      * represent that there is a value present for a key attribute that
    4198             :      * exceeds pg_index.indnkeyatts for the index.
    4199             :      */
    4200       26470 :     return tupnatts > 0 && tupnatts <= nkeyatts;
    4201             : }
    4202             : 
    4203             : /*
    4204             :  *
    4205             :  *  _bt_check_third_page() -- check whether tuple fits on a btree page at all.
    4206             :  *
    4207             :  * We actually need to be able to fit three items on every page, so restrict
    4208             :  * any one item to 1/3 the per-page available space.  Note that itemsz should
    4209             :  * not include the ItemId overhead.
    4210             :  *
    4211             :  * It might be useful to apply TOAST methods rather than throw an error here.
    4212             :  * Using out of line storage would break assumptions made by suffix truncation
    4213             :  * and by contrib/amcheck, though.
    4214             :  */
    4215             : void
    4216         264 : _bt_check_third_page(Relation rel, Relation heap, bool needheaptidspace,
    4217             :                      Page page, IndexTuple newtup)
    4218             : {
    4219             :     Size        itemsz;
    4220             :     BTPageOpaque opaque;
    4221             : 
    4222         264 :     itemsz = MAXALIGN(IndexTupleSize(newtup));
    4223             : 
    4224             :     /* Double check item size against limit */
    4225         264 :     if (itemsz <= BTMaxItemSize)
    4226           0 :         return;
    4227             : 
    4228             :     /*
    4229             :      * Tuple is probably too large to fit on page, but it's possible that the
    4230             :      * index uses version 2 or version 3, or that page is an internal page, in
    4231             :      * which case a slightly higher limit applies.
    4232             :      */
    4233         264 :     if (!needheaptidspace && itemsz <= BTMaxItemSizeNoHeapTid)
    4234         264 :         return;
    4235             : 
    4236             :     /*
    4237             :      * Internal page insertions cannot fail here, because that would mean that
    4238             :      * an earlier leaf level insertion that should have failed didn't
    4239             :      */
    4240           0 :     opaque = BTPageGetOpaque(page);
    4241           0 :     if (!P_ISLEAF(opaque))
    4242           0 :         elog(ERROR, "cannot insert oversized tuple of size %zu on internal page of index \"%s\"",
    4243             :              itemsz, RelationGetRelationName(rel));
    4244             : 
    4245           0 :     ereport(ERROR,
    4246             :             (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
    4247             :              errmsg("index row size %zu exceeds btree version %u maximum %zu for index \"%s\"",
    4248             :                     itemsz,
    4249             :                     needheaptidspace ? BTREE_VERSION : BTREE_NOVAC_VERSION,
    4250             :                     needheaptidspace ? BTMaxItemSize : BTMaxItemSizeNoHeapTid,
    4251             :                     RelationGetRelationName(rel)),
    4252             :              errdetail("Index row references tuple (%u,%u) in relation \"%s\".",
    4253             :                        ItemPointerGetBlockNumber(BTreeTupleGetHeapTID(newtup)),
    4254             :                        ItemPointerGetOffsetNumber(BTreeTupleGetHeapTID(newtup)),
    4255             :                        RelationGetRelationName(heap)),
    4256             :              errhint("Values larger than 1/3 of a buffer page cannot be indexed.\n"
    4257             :                      "Consider a function index of an MD5 hash of the value, "
    4258             :                      "or use full text indexing."),
    4259             :              errtableconstraint(heap, RelationGetRelationName(rel))));
    4260             : }
    4261             : 
    4262             : /*
    4263             :  * Are all attributes in rel "equality is image equality" attributes?
    4264             :  *
    4265             :  * We use each attribute's BTEQUALIMAGE_PROC opclass procedure.  If any
    4266             :  * opclass either lacks a BTEQUALIMAGE_PROC procedure or returns false, we
    4267             :  * return false; otherwise we return true.
    4268             :  *
    4269             :  * Returned boolean value is stored in index metapage during index builds.
    4270             :  * Deduplication can only be used when we return true.
    4271             :  */
    4272             : bool
    4273       59380 : _bt_allequalimage(Relation rel, bool debugmessage)
    4274             : {
    4275       59380 :     bool        allequalimage = true;
    4276             : 
    4277             :     /* INCLUDE indexes can never support deduplication */
    4278       59380 :     if (IndexRelationGetNumberOfAttributes(rel) !=
    4279       59380 :         IndexRelationGetNumberOfKeyAttributes(rel))
    4280         292 :         return false;
    4281             : 
    4282      156112 :     for (int i = 0; i < IndexRelationGetNumberOfKeyAttributes(rel); i++)
    4283             :     {
    4284       97560 :         Oid         opfamily = rel->rd_opfamily[i];
    4285       97560 :         Oid         opcintype = rel->rd_opcintype[i];
    4286       97560 :         Oid         collation = rel->rd_indcollation[i];
    4287             :         Oid         equalimageproc;
    4288             : 
    4289       97560 :         equalimageproc = get_opfamily_proc(opfamily, opcintype, opcintype,
    4290             :                                            BTEQUALIMAGE_PROC);
    4291             : 
    4292             :         /*
    4293             :          * If there is no BTEQUALIMAGE_PROC then deduplication is assumed to
    4294             :          * be unsafe.  Otherwise, actually call proc and see what it says.
    4295             :          */
    4296       97560 :         if (!OidIsValid(equalimageproc) ||
    4297       97068 :             !DatumGetBool(OidFunctionCall1Coll(equalimageproc, collation,
    4298             :                                                ObjectIdGetDatum(opcintype))))
    4299             :         {
    4300         536 :             allequalimage = false;
    4301         536 :             break;
    4302             :         }
    4303             :     }
    4304             : 
    4305       59088 :     if (debugmessage)
    4306             :     {
    4307       50992 :         if (allequalimage)
    4308       50456 :             elog(DEBUG1, "index \"%s\" can safely use deduplication",
    4309             :                  RelationGetRelationName(rel));
    4310             :         else
    4311         536 :             elog(DEBUG1, "index \"%s\" cannot use deduplication",
    4312             :                  RelationGetRelationName(rel));
    4313             :     }
    4314             : 
    4315       59088 :     return allequalimage;
    4316             : }

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