LCOV - code coverage report
Current view: top level - src/backend/access/index - indexam.c (source / functions) Hit Total Coverage
Test: PostgreSQL 13beta1 Lines: 199 203 98.0 %
Date: 2020-05-25 06:06:29 Functions: 25 25 100.0 %
Legend: Lines: hit not hit

          Line data    Source code
       1             : /*-------------------------------------------------------------------------
       2             :  *
       3             :  * indexam.c
       4             :  *    general index access method routines
       5             :  *
       6             :  * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
       7             :  * Portions Copyright (c) 1994, Regents of the University of California
       8             :  *
       9             :  *
      10             :  * IDENTIFICATION
      11             :  *    src/backend/access/index/indexam.c
      12             :  *
      13             :  * INTERFACE ROUTINES
      14             :  *      index_open      - open an index relation by relation OID
      15             :  *      index_close     - close an index relation
      16             :  *      index_beginscan - start a scan of an index with amgettuple
      17             :  *      index_beginscan_bitmap - start a scan of an index with amgetbitmap
      18             :  *      index_rescan    - restart a scan of an index
      19             :  *      index_endscan   - end a scan
      20             :  *      index_insert    - insert an index tuple into a relation
      21             :  *      index_markpos   - mark a scan position
      22             :  *      index_restrpos  - restore a scan position
      23             :  *      index_parallelscan_estimate - estimate shared memory for parallel scan
      24             :  *      index_parallelscan_initialize - initialize parallel scan
      25             :  *      index_parallelrescan  - (re)start a parallel scan of an index
      26             :  *      index_beginscan_parallel - join parallel index scan
      27             :  *      index_getnext_tid   - get the next TID from a scan
      28             :  *      index_fetch_heap        - get the scan's next heap tuple
      29             :  *      index_getnext_slot  - get the next tuple from a scan
      30             :  *      index_getbitmap - get all tuples from a scan
      31             :  *      index_bulk_delete   - bulk deletion of index tuples
      32             :  *      index_vacuum_cleanup    - post-deletion cleanup of an index
      33             :  *      index_can_return    - does index support index-only scans?
      34             :  *      index_getprocid - get a support procedure OID
      35             :  *      index_getprocinfo - get a support procedure's lookup info
      36             :  *
      37             :  * NOTES
      38             :  *      This file contains the index_ routines which used
      39             :  *      to be a scattered collection of stuff in access/genam.
      40             :  *
      41             :  *-------------------------------------------------------------------------
      42             :  */
      43             : 
      44             : #include "postgres.h"
      45             : 
      46             : #include "access/amapi.h"
      47             : #include "access/heapam.h"
      48             : #include "access/reloptions.h"
      49             : #include "access/relscan.h"
      50             : #include "access/tableam.h"
      51             : #include "access/transam.h"
      52             : #include "access/xlog.h"
      53             : #include "catalog/index.h"
      54             : #include "catalog/pg_amproc.h"
      55             : #include "catalog/pg_type.h"
      56             : #include "commands/defrem.h"
      57             : #include "nodes/makefuncs.h"
      58             : #include "pgstat.h"
      59             : #include "storage/bufmgr.h"
      60             : #include "storage/lmgr.h"
      61             : #include "storage/predicate.h"
      62             : #include "utils/ruleutils.h"
      63             : #include "utils/snapmgr.h"
      64             : #include "utils/syscache.h"
      65             : 
      66             : 
      67             : /* ----------------------------------------------------------------
      68             :  *                  macros used in index_ routines
      69             :  *
      70             :  * Note: the ReindexIsProcessingIndex() check in RELATION_CHECKS is there
      71             :  * to check that we don't try to scan or do retail insertions into an index
      72             :  * that is currently being rebuilt or pending rebuild.  This helps to catch
      73             :  * things that don't work when reindexing system catalogs.  The assertion
      74             :  * doesn't prevent the actual rebuild because we don't use RELATION_CHECKS
      75             :  * when calling the index AM's ambuild routine, and there is no reason for
      76             :  * ambuild to call its subsidiary routines through this file.
      77             :  * ----------------------------------------------------------------
      78             :  */
      79             : #define RELATION_CHECKS \
      80             : ( \
      81             :     AssertMacro(RelationIsValid(indexRelation)), \
      82             :     AssertMacro(PointerIsValid(indexRelation->rd_indam)), \
      83             :     AssertMacro(!ReindexIsProcessingIndex(RelationGetRelid(indexRelation))) \
      84             : )
      85             : 
      86             : #define SCAN_CHECKS \
      87             : ( \
      88             :     AssertMacro(IndexScanIsValid(scan)), \
      89             :     AssertMacro(RelationIsValid(scan->indexRelation)), \
      90             :     AssertMacro(PointerIsValid(scan->indexRelation->rd_indam)) \
      91             : )
      92             : 
      93             : #define CHECK_REL_PROCEDURE(pname) \
      94             : do { \
      95             :     if (indexRelation->rd_indam->pname == NULL) \
      96             :         elog(ERROR, "function %s is not defined for index %s", \
      97             :              CppAsString(pname), RelationGetRelationName(indexRelation)); \
      98             : } while(0)
      99             : 
     100             : #define CHECK_SCAN_PROCEDURE(pname) \
     101             : do { \
     102             :     if (scan->indexRelation->rd_indam->pname == NULL) \
     103             :         elog(ERROR, "function %s is not defined for index %s", \
     104             :              CppAsString(pname), RelationGetRelationName(scan->indexRelation)); \
     105             : } while(0)
     106             : 
     107             : static IndexScanDesc index_beginscan_internal(Relation indexRelation,
     108             :                                               int nkeys, int norderbys, Snapshot snapshot,
     109             :                                               ParallelIndexScanDesc pscan, bool temp_snap);
     110             : 
     111             : 
     112             : /* ----------------------------------------------------------------
     113             :  *                 index_ interface functions
     114             :  * ----------------------------------------------------------------
     115             :  */
     116             : 
     117             : /* ----------------
     118             :  *      index_open - open an index relation by relation OID
     119             :  *
     120             :  *      If lockmode is not "NoLock", the specified kind of lock is
     121             :  *      obtained on the index.  (Generally, NoLock should only be
     122             :  *      used if the caller knows it has some appropriate lock on the
     123             :  *      index already.)
     124             :  *
     125             :  *      An error is raised if the index does not exist.
     126             :  *
     127             :  *      This is a convenience routine adapted for indexscan use.
     128             :  *      Some callers may prefer to use relation_open directly.
     129             :  * ----------------
     130             :  */
     131             : Relation
     132    15729772 : index_open(Oid relationId, LOCKMODE lockmode)
     133             : {
     134             :     Relation    r;
     135             : 
     136    15729772 :     r = relation_open(relationId, lockmode);
     137             : 
     138    15729768 :     if (r->rd_rel->relkind != RELKIND_INDEX &&
     139        2004 :         r->rd_rel->relkind != RELKIND_PARTITIONED_INDEX)
     140          16 :         ereport(ERROR,
     141             :                 (errcode(ERRCODE_WRONG_OBJECT_TYPE),
     142             :                  errmsg("\"%s\" is not an index",
     143             :                         RelationGetRelationName(r))));
     144             : 
     145    15729752 :     return r;
     146             : }
     147             : 
     148             : /* ----------------
     149             :  *      index_close - close an index relation
     150             :  *
     151             :  *      If lockmode is not "NoLock", we then release the specified lock.
     152             :  *
     153             :  *      Note that it is often sensible to hold a lock beyond index_close;
     154             :  *      in that case, the lock is released automatically at xact end.
     155             :  * ----------------
     156             :  */
     157             : void
     158    15798896 : index_close(Relation relation, LOCKMODE lockmode)
     159             : {
     160    15798896 :     LockRelId   relid = relation->rd_lockInfo.lockRelId;
     161             : 
     162             :     Assert(lockmode >= NoLock && lockmode < MAX_LOCKMODES);
     163             : 
     164             :     /* The relcache does the real work... */
     165    15798896 :     RelationClose(relation);
     166             : 
     167    15798896 :     if (lockmode != NoLock)
     168    14905308 :         UnlockRelationId(&relid, lockmode);
     169    15798896 : }
     170             : 
     171             : /* ----------------
     172             :  *      index_insert - insert an index tuple into a relation
     173             :  * ----------------
     174             :  */
     175             : bool
     176    11737924 : index_insert(Relation indexRelation,
     177             :              Datum *values,
     178             :              bool *isnull,
     179             :              ItemPointer heap_t_ctid,
     180             :              Relation heapRelation,
     181             :              IndexUniqueCheck checkUnique,
     182             :              IndexInfo *indexInfo)
     183             : {
     184             :     RELATION_CHECKS;
     185    11737924 :     CHECK_REL_PROCEDURE(aminsert);
     186             : 
     187    11737924 :     if (!(indexRelation->rd_indam->ampredlocks))
     188      174380 :         CheckForSerializableConflictIn(indexRelation,
     189             :                                        (ItemPointer) NULL,
     190             :                                        InvalidBlockNumber);
     191             : 
     192    11737924 :     return indexRelation->rd_indam->aminsert(indexRelation, values, isnull,
     193             :                                              heap_t_ctid, heapRelation,
     194             :                                              checkUnique, indexInfo);
     195             : }
     196             : 
     197             : /*
     198             :  * index_beginscan - start a scan of an index with amgettuple
     199             :  *
     200             :  * Caller must be holding suitable locks on the heap and the index.
     201             :  */
     202             : IndexScanDesc
     203    10990252 : index_beginscan(Relation heapRelation,
     204             :                 Relation indexRelation,
     205             :                 Snapshot snapshot,
     206             :                 int nkeys, int norderbys)
     207             : {
     208             :     IndexScanDesc scan;
     209             : 
     210    10990252 :     scan = index_beginscan_internal(indexRelation, nkeys, norderbys, snapshot, NULL, false);
     211             : 
     212             :     /*
     213             :      * Save additional parameters into the scandesc.  Everything else was set
     214             :      * up by RelationGetIndexScan.
     215             :      */
     216    10990252 :     scan->heapRelation = heapRelation;
     217    10990252 :     scan->xs_snapshot = snapshot;
     218             : 
     219             :     /* prepare to fetch index matches from table */
     220    10990252 :     scan->xs_heapfetch = table_index_fetch_begin(heapRelation);
     221             : 
     222    10990252 :     return scan;
     223             : }
     224             : 
     225             : /*
     226             :  * index_beginscan_bitmap - start a scan of an index with amgetbitmap
     227             :  *
     228             :  * As above, caller had better be holding some lock on the parent heap
     229             :  * relation, even though it's not explicitly mentioned here.
     230             :  */
     231             : IndexScanDesc
     232       20790 : index_beginscan_bitmap(Relation indexRelation,
     233             :                        Snapshot snapshot,
     234             :                        int nkeys)
     235             : {
     236             :     IndexScanDesc scan;
     237             : 
     238       20790 :     scan = index_beginscan_internal(indexRelation, nkeys, 0, snapshot, NULL, false);
     239             : 
     240             :     /*
     241             :      * Save additional parameters into the scandesc.  Everything else was set
     242             :      * up by RelationGetIndexScan.
     243             :      */
     244       20790 :     scan->xs_snapshot = snapshot;
     245             : 
     246       20790 :     return scan;
     247             : }
     248             : 
     249             : /*
     250             :  * index_beginscan_internal --- common code for index_beginscan variants
     251             :  */
     252             : static IndexScanDesc
     253    11011266 : index_beginscan_internal(Relation indexRelation,
     254             :                          int nkeys, int norderbys, Snapshot snapshot,
     255             :                          ParallelIndexScanDesc pscan, bool temp_snap)
     256             : {
     257             :     IndexScanDesc scan;
     258             : 
     259             :     RELATION_CHECKS;
     260    11011266 :     CHECK_REL_PROCEDURE(ambeginscan);
     261             : 
     262    11011266 :     if (!(indexRelation->rd_indam->ampredlocks))
     263        1602 :         PredicateLockRelation(indexRelation, snapshot);
     264             : 
     265             :     /*
     266             :      * We hold a reference count to the relcache entry throughout the scan.
     267             :      */
     268    11011266 :     RelationIncrementReferenceCount(indexRelation);
     269             : 
     270             :     /*
     271             :      * Tell the AM to open a scan.
     272             :      */
     273    11011266 :     scan = indexRelation->rd_indam->ambeginscan(indexRelation, nkeys,
     274             :                                                 norderbys);
     275             :     /* Initialize information for parallel scan. */
     276    11011266 :     scan->parallel_scan = pscan;
     277    11011266 :     scan->xs_temp_snap = temp_snap;
     278             : 
     279    11011266 :     return scan;
     280             : }
     281             : 
     282             : /* ----------------
     283             :  *      index_rescan  - (re)start a scan of an index
     284             :  *
     285             :  * During a restart, the caller may specify a new set of scankeys and/or
     286             :  * orderbykeys; but the number of keys cannot differ from what index_beginscan
     287             :  * was told.  (Later we might relax that to "must not exceed", but currently
     288             :  * the index AMs tend to assume that scan->numberOfKeys is what to believe.)
     289             :  * To restart the scan without changing keys, pass NULL for the key arrays.
     290             :  * (Of course, keys *must* be passed on the first call, unless
     291             :  * scan->numberOfKeys is zero.)
     292             :  * ----------------
     293             :  */
     294             : void
     295    11205340 : index_rescan(IndexScanDesc scan,
     296             :              ScanKey keys, int nkeys,
     297             :              ScanKey orderbys, int norderbys)
     298             : {
     299             :     SCAN_CHECKS;
     300    11205340 :     CHECK_SCAN_PROCEDURE(amrescan);
     301             : 
     302             :     Assert(nkeys == scan->numberOfKeys);
     303             :     Assert(norderbys == scan->numberOfOrderBys);
     304             : 
     305             :     /* Release resources (like buffer pins) from table accesses */
     306    11205340 :     if (scan->xs_heapfetch)
     307    11182396 :         table_index_fetch_reset(scan->xs_heapfetch);
     308             : 
     309    11205340 :     scan->kill_prior_tuple = false; /* for safety */
     310    11205340 :     scan->xs_heap_continue = false;
     311             : 
     312    11205340 :     scan->indexRelation->rd_indam->amrescan(scan, keys, nkeys,
     313             :                                             orderbys, norderbys);
     314    11205340 : }
     315             : 
     316             : /* ----------------
     317             :  *      index_endscan - end a scan
     318             :  * ----------------
     319             :  */
     320             : void
     321    11010474 : index_endscan(IndexScanDesc scan)
     322             : {
     323             :     SCAN_CHECKS;
     324    11010474 :     CHECK_SCAN_PROCEDURE(amendscan);
     325             : 
     326             :     /* Release resources (like buffer pins) from table accesses */
     327    11010474 :     if (scan->xs_heapfetch)
     328             :     {
     329    10989726 :         table_index_fetch_end(scan->xs_heapfetch);
     330    10989726 :         scan->xs_heapfetch = NULL;
     331             :     }
     332             : 
     333             :     /* End the AM's scan */
     334    11010474 :     scan->indexRelation->rd_indam->amendscan(scan);
     335             : 
     336             :     /* Release index refcount acquired by index_beginscan */
     337    11010474 :     RelationDecrementReferenceCount(scan->indexRelation);
     338             : 
     339    11010474 :     if (scan->xs_temp_snap)
     340         224 :         UnregisterSnapshot(scan->xs_snapshot);
     341             : 
     342             :     /* Release the scan data structure itself */
     343    11010474 :     IndexScanEnd(scan);
     344    11010474 : }
     345             : 
     346             : /* ----------------
     347             :  *      index_markpos  - mark a scan position
     348             :  * ----------------
     349             :  */
     350             : void
     351       88036 : index_markpos(IndexScanDesc scan)
     352             : {
     353             :     SCAN_CHECKS;
     354       88036 :     CHECK_SCAN_PROCEDURE(ammarkpos);
     355             : 
     356       88036 :     scan->indexRelation->rd_indam->ammarkpos(scan);
     357       88036 : }
     358             : 
     359             : /* ----------------
     360             :  *      index_restrpos  - restore a scan position
     361             :  *
     362             :  * NOTE: this only restores the internal scan state of the index AM.  See
     363             :  * comments for ExecRestrPos().
     364             :  *
     365             :  * NOTE: For heap, in the presence of HOT chains, mark/restore only works
     366             :  * correctly if the scan's snapshot is MVCC-safe; that ensures that there's at
     367             :  * most one returnable tuple in each HOT chain, and so restoring the prior
     368             :  * state at the granularity of the index AM is sufficient.  Since the only
     369             :  * current user of mark/restore functionality is nodeMergejoin.c, this
     370             :  * effectively means that merge-join plans only work for MVCC snapshots.  This
     371             :  * could be fixed if necessary, but for now it seems unimportant.
     372             :  * ----------------
     373             :  */
     374             : void
     375       36012 : index_restrpos(IndexScanDesc scan)
     376             : {
     377             :     Assert(IsMVCCSnapshot(scan->xs_snapshot));
     378             : 
     379             :     SCAN_CHECKS;
     380       36012 :     CHECK_SCAN_PROCEDURE(amrestrpos);
     381             : 
     382             :     /* release resources (like buffer pins) from table accesses */
     383       36012 :     if (scan->xs_heapfetch)
     384       36012 :         table_index_fetch_reset(scan->xs_heapfetch);
     385             : 
     386       36012 :     scan->kill_prior_tuple = false; /* for safety */
     387       36012 :     scan->xs_heap_continue = false;
     388             : 
     389       36012 :     scan->indexRelation->rd_indam->amrestrpos(scan);
     390       36012 : }
     391             : 
     392             : /*
     393             :  * index_parallelscan_estimate - estimate shared memory for parallel scan
     394             :  *
     395             :  * Currently, we don't pass any information to the AM-specific estimator,
     396             :  * so it can probably only return a constant.  In the future, we might need
     397             :  * to pass more information.
     398             :  */
     399             : Size
     400          32 : index_parallelscan_estimate(Relation indexRelation, Snapshot snapshot)
     401             : {
     402             :     Size        nbytes;
     403             : 
     404             :     RELATION_CHECKS;
     405             : 
     406          32 :     nbytes = offsetof(ParallelIndexScanDescData, ps_snapshot_data);
     407          32 :     nbytes = add_size(nbytes, EstimateSnapshotSpace(snapshot));
     408          32 :     nbytes = MAXALIGN(nbytes);
     409             : 
     410             :     /*
     411             :      * If amestimateparallelscan is not provided, assume there is no
     412             :      * AM-specific data needed.  (It's hard to believe that could work, but
     413             :      * it's easy enough to cater to it here.)
     414             :      */
     415          32 :     if (indexRelation->rd_indam->amestimateparallelscan != NULL)
     416          32 :         nbytes = add_size(nbytes,
     417          32 :                           indexRelation->rd_indam->amestimateparallelscan());
     418             : 
     419          32 :     return nbytes;
     420             : }
     421             : 
     422             : /*
     423             :  * index_parallelscan_initialize - initialize parallel scan
     424             :  *
     425             :  * We initialize both the ParallelIndexScanDesc proper and the AM-specific
     426             :  * information which follows it.
     427             :  *
     428             :  * This function calls access method specific initialization routine to
     429             :  * initialize am specific information.  Call this just once in the leader
     430             :  * process; then, individual workers attach via index_beginscan_parallel.
     431             :  */
     432             : void
     433          32 : index_parallelscan_initialize(Relation heapRelation, Relation indexRelation,
     434             :                               Snapshot snapshot, ParallelIndexScanDesc target)
     435             : {
     436             :     Size        offset;
     437             : 
     438             :     RELATION_CHECKS;
     439             : 
     440          32 :     offset = add_size(offsetof(ParallelIndexScanDescData, ps_snapshot_data),
     441             :                       EstimateSnapshotSpace(snapshot));
     442          32 :     offset = MAXALIGN(offset);
     443             : 
     444          32 :     target->ps_relid = RelationGetRelid(heapRelation);
     445          32 :     target->ps_indexid = RelationGetRelid(indexRelation);
     446          32 :     target->ps_offset = offset;
     447          32 :     SerializeSnapshot(snapshot, target->ps_snapshot_data);
     448             : 
     449             :     /* aminitparallelscan is optional; assume no-op if not provided by AM */
     450          32 :     if (indexRelation->rd_indam->aminitparallelscan != NULL)
     451             :     {
     452             :         void       *amtarget;
     453             : 
     454          32 :         amtarget = OffsetToPointer(target, offset);
     455          32 :         indexRelation->rd_indam->aminitparallelscan(amtarget);
     456             :     }
     457          32 : }
     458             : 
     459             : /* ----------------
     460             :  *      index_parallelrescan  - (re)start a parallel scan of an index
     461             :  * ----------------
     462             :  */
     463             : void
     464          16 : index_parallelrescan(IndexScanDesc scan)
     465             : {
     466             :     SCAN_CHECKS;
     467             : 
     468          16 :     if (scan->xs_heapfetch)
     469          16 :         table_index_fetch_reset(scan->xs_heapfetch);
     470             : 
     471             :     /* amparallelrescan is optional; assume no-op if not provided by AM */
     472          16 :     if (scan->indexRelation->rd_indam->amparallelrescan != NULL)
     473          16 :         scan->indexRelation->rd_indam->amparallelrescan(scan);
     474          16 : }
     475             : 
     476             : /*
     477             :  * index_beginscan_parallel - join parallel index scan
     478             :  *
     479             :  * Caller must be holding suitable locks on the heap and the index.
     480             :  */
     481             : IndexScanDesc
     482         224 : index_beginscan_parallel(Relation heaprel, Relation indexrel, int nkeys,
     483             :                          int norderbys, ParallelIndexScanDesc pscan)
     484             : {
     485             :     Snapshot    snapshot;
     486             :     IndexScanDesc scan;
     487             : 
     488             :     Assert(RelationGetRelid(heaprel) == pscan->ps_relid);
     489         224 :     snapshot = RestoreSnapshot(pscan->ps_snapshot_data);
     490         224 :     RegisterSnapshot(snapshot);
     491         224 :     scan = index_beginscan_internal(indexrel, nkeys, norderbys, snapshot,
     492             :                                     pscan, true);
     493             : 
     494             :     /*
     495             :      * Save additional parameters into the scandesc.  Everything else was set
     496             :      * up by index_beginscan_internal.
     497             :      */
     498         224 :     scan->heapRelation = heaprel;
     499         224 :     scan->xs_snapshot = snapshot;
     500             : 
     501             :     /* prepare to fetch index matches from table */
     502         224 :     scan->xs_heapfetch = table_index_fetch_begin(heaprel);
     503             : 
     504         224 :     return scan;
     505             : }
     506             : 
     507             : /* ----------------
     508             :  * index_getnext_tid - get the next TID from a scan
     509             :  *
     510             :  * The result is the next TID satisfying the scan keys,
     511             :  * or NULL if no more matching tuples exist.
     512             :  * ----------------
     513             :  */
     514             : ItemPointer
     515    22244788 : index_getnext_tid(IndexScanDesc scan, ScanDirection direction)
     516             : {
     517             :     bool        found;
     518             : 
     519             :     SCAN_CHECKS;
     520    22244788 :     CHECK_SCAN_PROCEDURE(amgettuple);
     521             : 
     522             :     Assert(TransactionIdIsValid(RecentGlobalXmin));
     523             : 
     524             :     /*
     525             :      * The AM's amgettuple proc finds the next index entry matching the scan
     526             :      * keys, and puts the TID into scan->xs_heaptid.  It should also set
     527             :      * scan->xs_recheck and possibly scan->xs_itup/scan->xs_hitup, though we
     528             :      * pay no attention to those fields here.
     529             :      */
     530    22244788 :     found = scan->indexRelation->rd_indam->amgettuple(scan, direction);
     531             : 
     532             :     /* Reset kill flag immediately for safety */
     533    22244786 :     scan->kill_prior_tuple = false;
     534    22244786 :     scan->xs_heap_continue = false;
     535             : 
     536             :     /* If we're out of index entries, we're done */
     537    22244786 :     if (!found)
     538             :     {
     539             :         /* release resources (like buffer pins) from table accesses */
     540     4192448 :         if (scan->xs_heapfetch)
     541     4192448 :             table_index_fetch_reset(scan->xs_heapfetch);
     542             : 
     543     4192448 :         return NULL;
     544             :     }
     545             :     Assert(ItemPointerIsValid(&scan->xs_heaptid));
     546             : 
     547    18052338 :     pgstat_count_index_tuples(scan->indexRelation, 1);
     548             : 
     549             :     /* Return the TID of the tuple we found. */
     550    18052338 :     return &scan->xs_heaptid;
     551             : }
     552             : 
     553             : /* ----------------
     554             :  *      index_fetch_heap - get the scan's next heap tuple
     555             :  *
     556             :  * The result is a visible heap tuple associated with the index TID most
     557             :  * recently fetched by index_getnext_tid, or NULL if no more matching tuples
     558             :  * exist.  (There can be more than one matching tuple because of HOT chains,
     559             :  * although when using an MVCC snapshot it should be impossible for more than
     560             :  * one such tuple to exist.)
     561             :  *
     562             :  * On success, the buffer containing the heap tup is pinned (the pin will be
     563             :  * dropped in a future index_getnext_tid, index_fetch_heap or index_endscan
     564             :  * call).
     565             :  *
     566             :  * Note: caller must check scan->xs_recheck, and perform rechecking of the
     567             :  * scan keys if required.  We do not do that here because we don't have
     568             :  * enough information to do it efficiently in the general case.
     569             :  * ----------------
     570             :  */
     571             : bool
     572    16273830 : index_fetch_heap(IndexScanDesc scan, TupleTableSlot *slot)
     573             : {
     574    16273830 :     bool        all_dead = false;
     575             :     bool        found;
     576             : 
     577    16273830 :     found = table_index_fetch_tuple(scan->xs_heapfetch, &scan->xs_heaptid,
     578             :                                     scan->xs_snapshot, slot,
     579             :                                     &scan->xs_heap_continue, &all_dead);
     580             : 
     581    16273830 :     if (found)
     582    15737216 :         pgstat_count_heap_fetch(scan->indexRelation);
     583             : 
     584             :     /*
     585             :      * If we scanned a whole HOT chain and found only dead tuples, tell index
     586             :      * AM to kill its entry for that TID (this will take effect in the next
     587             :      * amgettuple call, in index_getnext_tid).  We do not do this when in
     588             :      * recovery because it may violate MVCC to do so.  See comments in
     589             :      * RelationGetIndexScan().
     590             :      */
     591    16273830 :     if (!scan->xactStartedInRecovery)
     592    16207114 :         scan->kill_prior_tuple = all_dead;
     593             : 
     594    16273830 :     return found;
     595             : }
     596             : 
     597             : /* ----------------
     598             :  *      index_getnext_slot - get the next tuple from a scan
     599             :  *
     600             :  * The result is true if a tuple satisfying the scan keys and the snapshot was
     601             :  * found, false otherwise.  The tuple is stored in the specified slot.
     602             :  *
     603             :  * On success, resources (like buffer pins) are likely to be held, and will be
     604             :  * dropped by a future index_getnext_tid, index_fetch_heap or index_endscan
     605             :  * call).
     606             :  *
     607             :  * Note: caller must check scan->xs_recheck, and perform rechecking of the
     608             :  * scan keys if required.  We do not do that here because we don't have
     609             :  * enough information to do it efficiently in the general case.
     610             :  * ----------------
     611             :  */
     612             : bool
     613    19509824 : index_getnext_slot(IndexScanDesc scan, ScanDirection direction, TupleTableSlot *slot)
     614             : {
     615             :     for (;;)
     616             :     {
     617    19509824 :         if (!scan->xs_heap_continue)
     618             :         {
     619             :             ItemPointer tid;
     620             : 
     621             :             /* Time to fetch the next TID from the index */
     622    19366850 :             tid = index_getnext_tid(scan, direction);
     623             : 
     624             :             /* If we're out of index entries, we're done */
     625    19366848 :             if (tid == NULL)
     626     4183094 :                 break;
     627             : 
     628             :             Assert(ItemPointerEquals(tid, &scan->xs_heaptid));
     629             :         }
     630             : 
     631             :         /*
     632             :          * Fetch the next (or only) visible heap tuple for this index entry.
     633             :          * If we don't find anything, loop around and grab the next TID from
     634             :          * the index.
     635             :          */
     636             :         Assert(ItemPointerIsValid(&scan->xs_heaptid));
     637    15326728 :         if (index_fetch_heap(scan, slot))
     638    14796250 :             return true;
     639             :     }
     640             : 
     641     4183094 :     return false;
     642             : }
     643             : 
     644             : /* ----------------
     645             :  *      index_getbitmap - get all tuples at once from an index scan
     646             :  *
     647             :  * Adds the TIDs of all heap tuples satisfying the scan keys to a bitmap.
     648             :  * Since there's no interlock between the index scan and the eventual heap
     649             :  * access, this is only safe to use with MVCC-based snapshots: the heap
     650             :  * item slot could have been replaced by a newer tuple by the time we get
     651             :  * to it.
     652             :  *
     653             :  * Returns the number of matching tuples found.  (Note: this might be only
     654             :  * approximate, so it should only be used for statistical purposes.)
     655             :  * ----------------
     656             :  */
     657             : int64
     658       15786 : index_getbitmap(IndexScanDesc scan, TIDBitmap *bitmap)
     659             : {
     660             :     int64       ntids;
     661             : 
     662             :     SCAN_CHECKS;
     663       15786 :     CHECK_SCAN_PROCEDURE(amgetbitmap);
     664             : 
     665             :     /* just make sure this is false... */
     666       15786 :     scan->kill_prior_tuple = false;
     667             : 
     668             :     /*
     669             :      * have the am's getbitmap proc do all the work.
     670             :      */
     671       15786 :     ntids = scan->indexRelation->rd_indam->amgetbitmap(scan, bitmap);
     672             : 
     673       15786 :     pgstat_count_index_tuples(scan->indexRelation, ntids);
     674             : 
     675       15786 :     return ntids;
     676             : }
     677             : 
     678             : /* ----------------
     679             :  *      index_bulk_delete - do mass deletion of index entries
     680             :  *
     681             :  *      callback routine tells whether a given main-heap tuple is
     682             :  *      to be deleted
     683             :  *
     684             :  *      return value is an optional palloc'd struct of statistics
     685             :  * ----------------
     686             :  */
     687             : IndexBulkDeleteResult *
     688        4126 : index_bulk_delete(IndexVacuumInfo *info,
     689             :                   IndexBulkDeleteResult *stats,
     690             :                   IndexBulkDeleteCallback callback,
     691             :                   void *callback_state)
     692             : {
     693        4126 :     Relation    indexRelation = info->index;
     694             : 
     695             :     RELATION_CHECKS;
     696        4126 :     CHECK_REL_PROCEDURE(ambulkdelete);
     697             : 
     698        4126 :     return indexRelation->rd_indam->ambulkdelete(info, stats,
     699             :                                                  callback, callback_state);
     700             : }
     701             : 
     702             : /* ----------------
     703             :  *      index_vacuum_cleanup - do post-deletion cleanup of an index
     704             :  *
     705             :  *      return value is an optional palloc'd struct of statistics
     706             :  * ----------------
     707             :  */
     708             : IndexBulkDeleteResult *
     709      115056 : index_vacuum_cleanup(IndexVacuumInfo *info,
     710             :                      IndexBulkDeleteResult *stats)
     711             : {
     712      115056 :     Relation    indexRelation = info->index;
     713             : 
     714             :     RELATION_CHECKS;
     715      115056 :     CHECK_REL_PROCEDURE(amvacuumcleanup);
     716             : 
     717      115056 :     return indexRelation->rd_indam->amvacuumcleanup(info, stats);
     718             : }
     719             : 
     720             : /* ----------------
     721             :  *      index_can_return
     722             :  *
     723             :  *      Does the index access method support index-only scans for the given
     724             :  *      column?
     725             :  * ----------------
     726             :  */
     727             : bool
     728      758842 : index_can_return(Relation indexRelation, int attno)
     729             : {
     730             :     RELATION_CHECKS;
     731             : 
     732             :     /* amcanreturn is optional; assume false if not provided by AM */
     733      758842 :     if (indexRelation->rd_indam->amcanreturn == NULL)
     734      121534 :         return false;
     735             : 
     736      637308 :     return indexRelation->rd_indam->amcanreturn(indexRelation, attno);
     737             : }
     738             : 
     739             : /* ----------------
     740             :  *      index_getprocid
     741             :  *
     742             :  *      Index access methods typically require support routines that are
     743             :  *      not directly the implementation of any WHERE-clause query operator
     744             :  *      and so cannot be kept in pg_amop.  Instead, such routines are kept
     745             :  *      in pg_amproc.  These registered procedure OIDs are assigned numbers
     746             :  *      according to a convention established by the access method.
     747             :  *      The general index code doesn't know anything about the routines
     748             :  *      involved; it just builds an ordered list of them for
     749             :  *      each attribute on which an index is defined.
     750             :  *
     751             :  *      As of Postgres 8.3, support routines within an operator family
     752             :  *      are further subdivided by the "left type" and "right type" of the
     753             :  *      query operator(s) that they support.  The "default" functions for a
     754             :  *      particular indexed attribute are those with both types equal to
     755             :  *      the index opclass' opcintype (note that this is subtly different
     756             :  *      from the indexed attribute's own type: it may be a binary-compatible
     757             :  *      type instead).  Only the default functions are stored in relcache
     758             :  *      entries --- access methods can use the syscache to look up non-default
     759             :  *      functions.
     760             :  *
     761             :  *      This routine returns the requested default procedure OID for a
     762             :  *      particular indexed attribute.
     763             :  * ----------------
     764             :  */
     765             : RegProcedure
     766     9807520 : index_getprocid(Relation irel,
     767             :                 AttrNumber attnum,
     768             :                 uint16 procnum)
     769             : {
     770             :     RegProcedure *loc;
     771             :     int         nproc;
     772             :     int         procindex;
     773             : 
     774     9807520 :     nproc = irel->rd_indam->amsupport;
     775             : 
     776             :     Assert(procnum > 0 && procnum <= (uint16) nproc);
     777             : 
     778     9807520 :     procindex = (nproc * (attnum - 1)) + (procnum - 1);
     779             : 
     780     9807520 :     loc = irel->rd_support;
     781             : 
     782             :     Assert(loc != NULL);
     783             : 
     784     9807520 :     return loc[procindex];
     785             : }
     786             : 
     787             : /* ----------------
     788             :  *      index_getprocinfo
     789             :  *
     790             :  *      This routine allows index AMs to keep fmgr lookup info for
     791             :  *      support procs in the relcache.  As above, only the "default"
     792             :  *      functions for any particular indexed attribute are cached.
     793             :  *
     794             :  * Note: the return value points into cached data that will be lost during
     795             :  * any relcache rebuild!  Therefore, either use the callinfo right away,
     796             :  * or save it only after having acquired some type of lock on the index rel.
     797             :  * ----------------
     798             :  */
     799             : FmgrInfo *
     800    50735412 : index_getprocinfo(Relation irel,
     801             :                   AttrNumber attnum,
     802             :                   uint16 procnum)
     803             : {
     804             :     FmgrInfo   *locinfo;
     805             :     int         nproc;
     806             :     int         optsproc;
     807             :     int         procindex;
     808             : 
     809    50735412 :     nproc = irel->rd_indam->amsupport;
     810    50735412 :     optsproc = irel->rd_indam->amoptsprocnum;
     811             : 
     812             :     Assert(procnum > 0 && procnum <= (uint16) nproc);
     813             : 
     814    50735412 :     procindex = (nproc * (attnum - 1)) + (procnum - 1);
     815             : 
     816    50735412 :     locinfo = irel->rd_supportinfo;
     817             : 
     818             :     Assert(locinfo != NULL);
     819             : 
     820    50735412 :     locinfo += procindex;
     821             : 
     822             :     /* Initialize the lookup info if first time through */
     823    50735412 :     if (locinfo->fn_oid == InvalidOid)
     824             :     {
     825      539202 :         RegProcedure *loc = irel->rd_support;
     826             :         RegProcedure procId;
     827             : 
     828             :         Assert(loc != NULL);
     829             : 
     830      539202 :         procId = loc[procindex];
     831             : 
     832             :         /*
     833             :          * Complain if function was not found during IndexSupportInitialize.
     834             :          * This should not happen unless the system tables contain bogus
     835             :          * entries for the index opclass.  (If an AM wants to allow a support
     836             :          * function to be optional, it can use index_getprocid.)
     837             :          */
     838      539202 :         if (!RegProcedureIsValid(procId))
     839           0 :             elog(ERROR, "missing support function %d for attribute %d of index \"%s\"",
     840             :                  procnum, attnum, RelationGetRelationName(irel));
     841             : 
     842      539202 :         fmgr_info_cxt(procId, locinfo, irel->rd_indexcxt);
     843             : 
     844      539202 :         if (procnum != optsproc)
     845             :         {
     846             :             /* Initialize locinfo->fn_expr with opclass options Const */
     847      539070 :             bytea     **attoptions = RelationGetIndexAttOptions(irel, false);
     848      539070 :             MemoryContext oldcxt = MemoryContextSwitchTo(irel->rd_indexcxt);
     849             : 
     850      539070 :             set_fn_opclass_options(locinfo, attoptions[attnum - 1]);
     851             : 
     852      539070 :             MemoryContextSwitchTo(oldcxt);
     853             :         }
     854             :     }
     855             : 
     856    50735412 :     return locinfo;
     857             : }
     858             : 
     859             : /* ----------------
     860             :  *      index_store_float8_orderby_distances
     861             :  *
     862             :  *      Convert AM distance function's results (that can be inexact)
     863             :  *      to ORDER BY types and save them into xs_orderbyvals/xs_orderbynulls
     864             :  *      for a possible recheck.
     865             :  * ----------------
     866             :  */
     867             : void
     868      243062 : index_store_float8_orderby_distances(IndexScanDesc scan, Oid *orderByTypes,
     869             :                                      IndexOrderByDistance *distances,
     870             :                                      bool recheckOrderBy)
     871             : {
     872             :     int         i;
     873             : 
     874             :     Assert(distances || !recheckOrderBy);
     875             : 
     876      243062 :     scan->xs_recheckorderby = recheckOrderBy;
     877             : 
     878      486136 :     for (i = 0; i < scan->numberOfOrderBys; i++)
     879             :     {
     880      243074 :         if (orderByTypes[i] == FLOAT8OID)
     881             :         {
     882             : #ifndef USE_FLOAT8_BYVAL
     883             :             /* must free any old value to avoid memory leakage */
     884             :             if (!scan->xs_orderbynulls[i])
     885             :                 pfree(DatumGetPointer(scan->xs_orderbyvals[i]));
     886             : #endif
     887      242944 :             if (distances && !distances[i].isnull)
     888             :             {
     889      242904 :                 scan->xs_orderbyvals[i] = Float8GetDatum(distances[i].value);
     890      242904 :                 scan->xs_orderbynulls[i] = false;
     891             :             }
     892             :             else
     893             :             {
     894          40 :                 scan->xs_orderbyvals[i] = (Datum) 0;
     895          40 :                 scan->xs_orderbynulls[i] = true;
     896             :             }
     897             :         }
     898         130 :         else if (orderByTypes[i] == FLOAT4OID)
     899             :         {
     900             :             /* convert distance function's result to ORDER BY type */
     901          70 :             if (distances && !distances[i].isnull)
     902             :             {
     903          70 :                 scan->xs_orderbyvals[i] = Float4GetDatum((float4) distances[i].value);
     904          70 :                 scan->xs_orderbynulls[i] = false;
     905             :             }
     906             :             else
     907             :             {
     908           0 :                 scan->xs_orderbyvals[i] = (Datum) 0;
     909           0 :                 scan->xs_orderbynulls[i] = true;
     910             :             }
     911             :         }
     912             :         else
     913             :         {
     914             :             /*
     915             :              * If the ordering operator's return value is anything else, we
     916             :              * don't know how to convert the float8 bound calculated by the
     917             :              * distance function to that.  The executor won't actually need
     918             :              * the order by values we return here, if there are no lossy
     919             :              * results, so only insist on converting if the *recheck flag is
     920             :              * set.
     921             :              */
     922          60 :             if (scan->xs_recheckorderby)
     923           0 :                 elog(ERROR, "ORDER BY operator must return float8 or float4 if the distance function is lossy");
     924          60 :             scan->xs_orderbynulls[i] = true;
     925             :         }
     926             :     }
     927      243062 : }
     928             : 
     929             : /* ----------------
     930             :  *      index_opclass_options
     931             :  *
     932             :  *      Parse opclass-specific options for index column.
     933             :  * ----------------
     934             :  */
     935             : bytea *
     936      443538 : index_opclass_options(Relation indrel, AttrNumber attnum, Datum attoptions,
     937             :                       bool validate)
     938             : {
     939      443538 :     int         amoptsprocnum = indrel->rd_indam->amoptsprocnum;
     940      443538 :     Oid         procid = InvalidOid;
     941             :     FmgrInfo   *procinfo;
     942             :     local_relopts relopts;
     943             : 
     944             :     /* fetch options support procedure if specified */
     945      443538 :     if (amoptsprocnum != 0)
     946      443482 :         procid = index_getprocid(indrel, attnum, amoptsprocnum);
     947             : 
     948      443538 :     if (!OidIsValid(procid))
     949             :     {
     950             :         Oid         opclass;
     951             :         Datum       indclassDatum;
     952             :         oidvector  *indclass;
     953             :         bool        isnull;
     954             : 
     955      443342 :         if (!DatumGetPointer(attoptions))
     956      443338 :             return NULL;        /* ok, no options, no procedure */
     957             : 
     958             :         /*
     959             :          * Report an error if the opclass's options-parsing procedure does not
     960             :          * exist but the opclass options are specified.
     961             :          */
     962           4 :         indclassDatum = SysCacheGetAttr(INDEXRELID, indrel->rd_indextuple,
     963             :                                         Anum_pg_index_indclass, &isnull);
     964             :         Assert(!isnull);
     965           4 :         indclass = (oidvector *) DatumGetPointer(indclassDatum);
     966           4 :         opclass = indclass->values[attnum - 1];
     967             : 
     968           4 :         ereport(ERROR,
     969             :                 (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
     970             :                  errmsg("operator class %s has no options",
     971             :                         generate_opclass_name(opclass))));
     972             :     }
     973             : 
     974         196 :     init_local_reloptions(&relopts, 0);
     975             : 
     976         196 :     procinfo = index_getprocinfo(indrel, attnum, amoptsprocnum);
     977             : 
     978         196 :     (void) FunctionCall1(procinfo, PointerGetDatum(&relopts));
     979             : 
     980         196 :     return build_local_reloptions(&relopts, attoptions, validate);
     981             : }

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