LCOV - code coverage report
Current view: top level - src/include/access - htup_details.h (source / functions) Hit Total Coverage
Test: PostgreSQL 17beta1 Lines: 16 17 94.1 %
Date: 2024-06-18 00:11:41 Functions: 2 2 100.0 %
Legend: Lines: hit not hit

          Line data    Source code
       1             : /*-------------------------------------------------------------------------
       2             :  *
       3             :  * htup_details.h
       4             :  *    POSTGRES heap tuple header definitions.
       5             :  *
       6             :  *
       7             :  * Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
       8             :  * Portions Copyright (c) 1994, Regents of the University of California
       9             :  *
      10             :  * src/include/access/htup_details.h
      11             :  *
      12             :  *-------------------------------------------------------------------------
      13             :  */
      14             : #ifndef HTUP_DETAILS_H
      15             : #define HTUP_DETAILS_H
      16             : 
      17             : #include "access/htup.h"
      18             : #include "access/transam.h"
      19             : #include "access/tupdesc.h"
      20             : #include "access/tupmacs.h"
      21             : #include "storage/bufpage.h"
      22             : #include "varatt.h"
      23             : 
      24             : /*
      25             :  * MaxTupleAttributeNumber limits the number of (user) columns in a tuple.
      26             :  * The key limit on this value is that the size of the fixed overhead for
      27             :  * a tuple, plus the size of the null-values bitmap (at 1 bit per column),
      28             :  * plus MAXALIGN alignment, must fit into t_hoff which is uint8.  On most
      29             :  * machines the upper limit without making t_hoff wider would be a little
      30             :  * over 1700.  We use round numbers here and for MaxHeapAttributeNumber
      31             :  * so that alterations in HeapTupleHeaderData layout won't change the
      32             :  * supported max number of columns.
      33             :  */
      34             : #define MaxTupleAttributeNumber 1664    /* 8 * 208 */
      35             : 
      36             : /*
      37             :  * MaxHeapAttributeNumber limits the number of (user) columns in a table.
      38             :  * This should be somewhat less than MaxTupleAttributeNumber.  It must be
      39             :  * at least one less, else we will fail to do UPDATEs on a maximal-width
      40             :  * table (because UPDATE has to form working tuples that include CTID).
      41             :  * In practice we want some additional daylight so that we can gracefully
      42             :  * support operations that add hidden "resjunk" columns, for example
      43             :  * SELECT * FROM wide_table ORDER BY foo, bar, baz.
      44             :  * In any case, depending on column data types you will likely be running
      45             :  * into the disk-block-based limit on overall tuple size if you have more
      46             :  * than a thousand or so columns.  TOAST won't help.
      47             :  */
      48             : #define MaxHeapAttributeNumber  1600    /* 8 * 200 */
      49             : 
      50             : /*
      51             :  * Heap tuple header.  To avoid wasting space, the fields should be
      52             :  * laid out in such a way as to avoid structure padding.
      53             :  *
      54             :  * Datums of composite types (row types) share the same general structure
      55             :  * as on-disk tuples, so that the same routines can be used to build and
      56             :  * examine them.  However the requirements are slightly different: a Datum
      57             :  * does not need any transaction visibility information, and it does need
      58             :  * a length word and some embedded type information.  We can achieve this
      59             :  * by overlaying the xmin/cmin/xmax/cmax/xvac fields of a heap tuple
      60             :  * with the fields needed in the Datum case.  Typically, all tuples built
      61             :  * in-memory will be initialized with the Datum fields; but when a tuple is
      62             :  * about to be inserted in a table, the transaction fields will be filled,
      63             :  * overwriting the datum fields.
      64             :  *
      65             :  * The overall structure of a heap tuple looks like:
      66             :  *          fixed fields (HeapTupleHeaderData struct)
      67             :  *          nulls bitmap (if HEAP_HASNULL is set in t_infomask)
      68             :  *          alignment padding (as needed to make user data MAXALIGN'd)
      69             :  *          object ID (if HEAP_HASOID_OLD is set in t_infomask, not created
      70             :  *          anymore)
      71             :  *          user data fields
      72             :  *
      73             :  * We store five "virtual" fields Xmin, Cmin, Xmax, Cmax, and Xvac in three
      74             :  * physical fields.  Xmin and Xmax are always really stored, but Cmin, Cmax
      75             :  * and Xvac share a field.  This works because we know that Cmin and Cmax
      76             :  * are only interesting for the lifetime of the inserting and deleting
      77             :  * transaction respectively.  If a tuple is inserted and deleted in the same
      78             :  * transaction, we store a "combo" command id that can be mapped to the real
      79             :  * cmin and cmax, but only by use of local state within the originating
      80             :  * backend.  See combocid.c for more details.  Meanwhile, Xvac is only set by
      81             :  * old-style VACUUM FULL, which does not have any command sub-structure and so
      82             :  * does not need either Cmin or Cmax.  (This requires that old-style VACUUM
      83             :  * FULL never try to move a tuple whose Cmin or Cmax is still interesting,
      84             :  * ie, an insert-in-progress or delete-in-progress tuple.)
      85             :  *
      86             :  * A word about t_ctid: whenever a new tuple is stored on disk, its t_ctid
      87             :  * is initialized with its own TID (location).  If the tuple is ever updated,
      88             :  * its t_ctid is changed to point to the replacement version of the tuple.  Or
      89             :  * if the tuple is moved from one partition to another, due to an update of
      90             :  * the partition key, t_ctid is set to a special value to indicate that
      91             :  * (see ItemPointerSetMovedPartitions).  Thus, a tuple is the latest version
      92             :  * of its row iff XMAX is invalid or
      93             :  * t_ctid points to itself (in which case, if XMAX is valid, the tuple is
      94             :  * either locked or deleted).  One can follow the chain of t_ctid links
      95             :  * to find the newest version of the row, unless it was moved to a different
      96             :  * partition.  Beware however that VACUUM might
      97             :  * erase the pointed-to (newer) tuple before erasing the pointing (older)
      98             :  * tuple.  Hence, when following a t_ctid link, it is necessary to check
      99             :  * to see if the referenced slot is empty or contains an unrelated tuple.
     100             :  * Check that the referenced tuple has XMIN equal to the referencing tuple's
     101             :  * XMAX to verify that it is actually the descendant version and not an
     102             :  * unrelated tuple stored into a slot recently freed by VACUUM.  If either
     103             :  * check fails, one may assume that there is no live descendant version.
     104             :  *
     105             :  * t_ctid is sometimes used to store a speculative insertion token, instead
     106             :  * of a real TID.  A speculative token is set on a tuple that's being
     107             :  * inserted, until the inserter is sure that it wants to go ahead with the
     108             :  * insertion.  Hence a token should only be seen on a tuple with an XMAX
     109             :  * that's still in-progress, or invalid/aborted.  The token is replaced with
     110             :  * the tuple's real TID when the insertion is confirmed.  One should never
     111             :  * see a speculative insertion token while following a chain of t_ctid links,
     112             :  * because they are not used on updates, only insertions.
     113             :  *
     114             :  * Following the fixed header fields, the nulls bitmap is stored (beginning
     115             :  * at t_bits).  The bitmap is *not* stored if t_infomask shows that there
     116             :  * are no nulls in the tuple.  If an OID field is present (as indicated by
     117             :  * t_infomask), then it is stored just before the user data, which begins at
     118             :  * the offset shown by t_hoff.  Note that t_hoff must be a multiple of
     119             :  * MAXALIGN.
     120             :  */
     121             : 
     122             : typedef struct HeapTupleFields
     123             : {
     124             :     TransactionId t_xmin;       /* inserting xact ID */
     125             :     TransactionId t_xmax;       /* deleting or locking xact ID */
     126             : 
     127             :     union
     128             :     {
     129             :         CommandId   t_cid;      /* inserting or deleting command ID, or both */
     130             :         TransactionId t_xvac;   /* old-style VACUUM FULL xact ID */
     131             :     }           t_field3;
     132             : } HeapTupleFields;
     133             : 
     134             : typedef struct DatumTupleFields
     135             : {
     136             :     int32       datum_len_;     /* varlena header (do not touch directly!) */
     137             : 
     138             :     int32       datum_typmod;   /* -1, or identifier of a record type */
     139             : 
     140             :     Oid         datum_typeid;   /* composite type OID, or RECORDOID */
     141             : 
     142             :     /*
     143             :      * datum_typeid cannot be a domain over composite, only plain composite,
     144             :      * even if the datum is meant as a value of a domain-over-composite type.
     145             :      * This is in line with the general principle that CoerceToDomain does not
     146             :      * change the physical representation of the base type value.
     147             :      *
     148             :      * Note: field ordering is chosen with thought that Oid might someday
     149             :      * widen to 64 bits.
     150             :      */
     151             : } DatumTupleFields;
     152             : 
     153             : struct HeapTupleHeaderData
     154             : {
     155             :     union
     156             :     {
     157             :         HeapTupleFields t_heap;
     158             :         DatumTupleFields t_datum;
     159             :     }           t_choice;
     160             : 
     161             :     ItemPointerData t_ctid;     /* current TID of this or newer tuple (or a
     162             :                                  * speculative insertion token) */
     163             : 
     164             :     /* Fields below here must match MinimalTupleData! */
     165             : 
     166             : #define FIELDNO_HEAPTUPLEHEADERDATA_INFOMASK2 2
     167             :     uint16      t_infomask2;    /* number of attributes + various flags */
     168             : 
     169             : #define FIELDNO_HEAPTUPLEHEADERDATA_INFOMASK 3
     170             :     uint16      t_infomask;     /* various flag bits, see below */
     171             : 
     172             : #define FIELDNO_HEAPTUPLEHEADERDATA_HOFF 4
     173             :     uint8       t_hoff;         /* sizeof header incl. bitmap, padding */
     174             : 
     175             :     /* ^ - 23 bytes - ^ */
     176             : 
     177             : #define FIELDNO_HEAPTUPLEHEADERDATA_BITS 5
     178             :     bits8       t_bits[FLEXIBLE_ARRAY_MEMBER];  /* bitmap of NULLs */
     179             : 
     180             :     /* MORE DATA FOLLOWS AT END OF STRUCT */
     181             : };
     182             : 
     183             : /* typedef appears in htup.h */
     184             : 
     185             : #define SizeofHeapTupleHeader offsetof(HeapTupleHeaderData, t_bits)
     186             : 
     187             : /*
     188             :  * information stored in t_infomask:
     189             :  */
     190             : #define HEAP_HASNULL            0x0001  /* has null attribute(s) */
     191             : #define HEAP_HASVARWIDTH        0x0002  /* has variable-width attribute(s) */
     192             : #define HEAP_HASEXTERNAL        0x0004  /* has external stored attribute(s) */
     193             : #define HEAP_HASOID_OLD         0x0008  /* has an object-id field */
     194             : #define HEAP_XMAX_KEYSHR_LOCK   0x0010  /* xmax is a key-shared locker */
     195             : #define HEAP_COMBOCID           0x0020  /* t_cid is a combo CID */
     196             : #define HEAP_XMAX_EXCL_LOCK     0x0040  /* xmax is exclusive locker */
     197             : #define HEAP_XMAX_LOCK_ONLY     0x0080  /* xmax, if valid, is only a locker */
     198             : 
     199             :  /* xmax is a shared locker */
     200             : #define HEAP_XMAX_SHR_LOCK  (HEAP_XMAX_EXCL_LOCK | HEAP_XMAX_KEYSHR_LOCK)
     201             : 
     202             : #define HEAP_LOCK_MASK  (HEAP_XMAX_SHR_LOCK | HEAP_XMAX_EXCL_LOCK | \
     203             :                          HEAP_XMAX_KEYSHR_LOCK)
     204             : #define HEAP_XMIN_COMMITTED     0x0100  /* t_xmin committed */
     205             : #define HEAP_XMIN_INVALID       0x0200  /* t_xmin invalid/aborted */
     206             : #define HEAP_XMIN_FROZEN        (HEAP_XMIN_COMMITTED|HEAP_XMIN_INVALID)
     207             : #define HEAP_XMAX_COMMITTED     0x0400  /* t_xmax committed */
     208             : #define HEAP_XMAX_INVALID       0x0800  /* t_xmax invalid/aborted */
     209             : #define HEAP_XMAX_IS_MULTI      0x1000  /* t_xmax is a MultiXactId */
     210             : #define HEAP_UPDATED            0x2000  /* this is UPDATEd version of row */
     211             : #define HEAP_MOVED_OFF          0x4000  /* moved to another place by pre-9.0
     212             :                                          * VACUUM FULL; kept for binary
     213             :                                          * upgrade support */
     214             : #define HEAP_MOVED_IN           0x8000  /* moved from another place by pre-9.0
     215             :                                          * VACUUM FULL; kept for binary
     216             :                                          * upgrade support */
     217             : #define HEAP_MOVED (HEAP_MOVED_OFF | HEAP_MOVED_IN)
     218             : 
     219             : #define HEAP_XACT_MASK          0xFFF0  /* visibility-related bits */
     220             : 
     221             : /*
     222             :  * A tuple is only locked (i.e. not updated by its Xmax) if the
     223             :  * HEAP_XMAX_LOCK_ONLY bit is set; or, for pg_upgrade's sake, if the Xmax is
     224             :  * not a multi and the EXCL_LOCK bit is set.
     225             :  *
     226             :  * See also HeapTupleHeaderIsOnlyLocked, which also checks for a possible
     227             :  * aborted updater transaction.
     228             :  *
     229             :  * Beware of multiple evaluations of the argument.
     230             :  */
     231             : #define HEAP_XMAX_IS_LOCKED_ONLY(infomask) \
     232             :     (((infomask) & HEAP_XMAX_LOCK_ONLY) || \
     233             :      (((infomask) & (HEAP_XMAX_IS_MULTI | HEAP_LOCK_MASK)) == HEAP_XMAX_EXCL_LOCK))
     234             : 
     235             : /*
     236             :  * A tuple that has HEAP_XMAX_IS_MULTI and HEAP_XMAX_LOCK_ONLY but neither of
     237             :  * HEAP_XMAX_EXCL_LOCK and HEAP_XMAX_KEYSHR_LOCK must come from a tuple that was
     238             :  * share-locked in 9.2 or earlier and then pg_upgrade'd.
     239             :  *
     240             :  * In 9.2 and prior, HEAP_XMAX_IS_MULTI was only set when there were multiple
     241             :  * FOR SHARE lockers of that tuple.  That set HEAP_XMAX_LOCK_ONLY (with a
     242             :  * different name back then) but neither of HEAP_XMAX_EXCL_LOCK and
     243             :  * HEAP_XMAX_KEYSHR_LOCK.  That combination is no longer possible in 9.3 and
     244             :  * up, so if we see that combination we know for certain that the tuple was
     245             :  * locked in an earlier release; since all such lockers are gone (they cannot
     246             :  * survive through pg_upgrade), such tuples can safely be considered not
     247             :  * locked.
     248             :  *
     249             :  * We must not resolve such multixacts locally, because the result would be
     250             :  * bogus, regardless of where they stand with respect to the current valid
     251             :  * multixact range.
     252             :  */
     253             : #define HEAP_LOCKED_UPGRADED(infomask) \
     254             : ( \
     255             :      ((infomask) & HEAP_XMAX_IS_MULTI) != 0 && \
     256             :      ((infomask) & HEAP_XMAX_LOCK_ONLY) != 0 && \
     257             :      (((infomask) & (HEAP_XMAX_EXCL_LOCK | HEAP_XMAX_KEYSHR_LOCK)) == 0) \
     258             : )
     259             : 
     260             : /*
     261             :  * Use these to test whether a particular lock is applied to a tuple
     262             :  */
     263             : #define HEAP_XMAX_IS_SHR_LOCKED(infomask) \
     264             :     (((infomask) & HEAP_LOCK_MASK) == HEAP_XMAX_SHR_LOCK)
     265             : #define HEAP_XMAX_IS_EXCL_LOCKED(infomask) \
     266             :     (((infomask) & HEAP_LOCK_MASK) == HEAP_XMAX_EXCL_LOCK)
     267             : #define HEAP_XMAX_IS_KEYSHR_LOCKED(infomask) \
     268             :     (((infomask) & HEAP_LOCK_MASK) == HEAP_XMAX_KEYSHR_LOCK)
     269             : 
     270             : /* turn these all off when Xmax is to change */
     271             : #define HEAP_XMAX_BITS (HEAP_XMAX_COMMITTED | HEAP_XMAX_INVALID | \
     272             :                         HEAP_XMAX_IS_MULTI | HEAP_LOCK_MASK | HEAP_XMAX_LOCK_ONLY)
     273             : 
     274             : /*
     275             :  * information stored in t_infomask2:
     276             :  */
     277             : #define HEAP_NATTS_MASK         0x07FF  /* 11 bits for number of attributes */
     278             : /* bits 0x1800 are available */
     279             : #define HEAP_KEYS_UPDATED       0x2000  /* tuple was updated and key cols
     280             :                                          * modified, or tuple deleted */
     281             : #define HEAP_HOT_UPDATED        0x4000  /* tuple was HOT-updated */
     282             : #define HEAP_ONLY_TUPLE         0x8000  /* this is heap-only tuple */
     283             : 
     284             : #define HEAP2_XACT_MASK         0xE000  /* visibility-related bits */
     285             : 
     286             : /*
     287             :  * HEAP_TUPLE_HAS_MATCH is a temporary flag used during hash joins.  It is
     288             :  * only used in tuples that are in the hash table, and those don't need
     289             :  * any visibility information, so we can overlay it on a visibility flag
     290             :  * instead of using up a dedicated bit.
     291             :  */
     292             : #define HEAP_TUPLE_HAS_MATCH    HEAP_ONLY_TUPLE /* tuple has a join match */
     293             : 
     294             : /*
     295             :  * HeapTupleHeader accessor macros
     296             :  *
     297             :  * Note: beware of multiple evaluations of "tup" argument.  But the Set
     298             :  * macros evaluate their other argument only once.
     299             :  */
     300             : 
     301             : /*
     302             :  * HeapTupleHeaderGetRawXmin returns the "raw" xmin field, which is the xid
     303             :  * originally used to insert the tuple.  However, the tuple might actually
     304             :  * be frozen (via HeapTupleHeaderSetXminFrozen) in which case the tuple's xmin
     305             :  * is visible to every snapshot.  Prior to PostgreSQL 9.4, we actually changed
     306             :  * the xmin to FrozenTransactionId, and that value may still be encountered
     307             :  * on disk.
     308             :  */
     309             : #define HeapTupleHeaderGetRawXmin(tup) \
     310             : ( \
     311             :     (tup)->t_choice.t_heap.t_xmin \
     312             : )
     313             : 
     314             : #define HeapTupleHeaderGetXmin(tup) \
     315             : ( \
     316             :     HeapTupleHeaderXminFrozen(tup) ? \
     317             :         FrozenTransactionId : HeapTupleHeaderGetRawXmin(tup) \
     318             : )
     319             : 
     320             : #define HeapTupleHeaderSetXmin(tup, xid) \
     321             : ( \
     322             :     (tup)->t_choice.t_heap.t_xmin = (xid) \
     323             : )
     324             : 
     325             : #define HeapTupleHeaderXminCommitted(tup) \
     326             : ( \
     327             :     ((tup)->t_infomask & HEAP_XMIN_COMMITTED) != 0 \
     328             : )
     329             : 
     330             : #define HeapTupleHeaderXminInvalid(tup) \
     331             : ( \
     332             :     ((tup)->t_infomask & (HEAP_XMIN_COMMITTED|HEAP_XMIN_INVALID)) == \
     333             :         HEAP_XMIN_INVALID \
     334             : )
     335             : 
     336             : #define HeapTupleHeaderXminFrozen(tup) \
     337             : ( \
     338             :     ((tup)->t_infomask & (HEAP_XMIN_FROZEN)) == HEAP_XMIN_FROZEN \
     339             : )
     340             : 
     341             : #define HeapTupleHeaderSetXminCommitted(tup) \
     342             : ( \
     343             :     AssertMacro(!HeapTupleHeaderXminInvalid(tup)), \
     344             :     ((tup)->t_infomask |= HEAP_XMIN_COMMITTED) \
     345             : )
     346             : 
     347             : #define HeapTupleHeaderSetXminInvalid(tup) \
     348             : ( \
     349             :     AssertMacro(!HeapTupleHeaderXminCommitted(tup)), \
     350             :     ((tup)->t_infomask |= HEAP_XMIN_INVALID) \
     351             : )
     352             : 
     353             : #define HeapTupleHeaderSetXminFrozen(tup) \
     354             : ( \
     355             :     AssertMacro(!HeapTupleHeaderXminInvalid(tup)), \
     356             :     ((tup)->t_infomask |= HEAP_XMIN_FROZEN) \
     357             : )
     358             : 
     359             : /*
     360             :  * HeapTupleHeaderGetRawXmax gets you the raw Xmax field.  To find out the Xid
     361             :  * that updated a tuple, you might need to resolve the MultiXactId if certain
     362             :  * bits are set.  HeapTupleHeaderGetUpdateXid checks those bits and takes care
     363             :  * to resolve the MultiXactId if necessary.  This might involve multixact I/O,
     364             :  * so it should only be used if absolutely necessary.
     365             :  */
     366             : #define HeapTupleHeaderGetUpdateXid(tup) \
     367             : ( \
     368             :     (!((tup)->t_infomask & HEAP_XMAX_INVALID) && \
     369             :      ((tup)->t_infomask & HEAP_XMAX_IS_MULTI) && \
     370             :      !((tup)->t_infomask & HEAP_XMAX_LOCK_ONLY)) ? \
     371             :         HeapTupleGetUpdateXid(tup) \
     372             :     : \
     373             :         HeapTupleHeaderGetRawXmax(tup) \
     374             : )
     375             : 
     376             : #define HeapTupleHeaderGetRawXmax(tup) \
     377             : ( \
     378             :     (tup)->t_choice.t_heap.t_xmax \
     379             : )
     380             : 
     381             : #define HeapTupleHeaderSetXmax(tup, xid) \
     382             : ( \
     383             :     (tup)->t_choice.t_heap.t_xmax = (xid) \
     384             : )
     385             : 
     386             : /*
     387             :  * HeapTupleHeaderGetRawCommandId will give you what's in the header whether
     388             :  * it is useful or not.  Most code should use HeapTupleHeaderGetCmin or
     389             :  * HeapTupleHeaderGetCmax instead, but note that those Assert that you can
     390             :  * get a legitimate result, ie you are in the originating transaction!
     391             :  */
     392             : #define HeapTupleHeaderGetRawCommandId(tup) \
     393             : ( \
     394             :     (tup)->t_choice.t_heap.t_field3.t_cid \
     395             : )
     396             : 
     397             : /* SetCmin is reasonably simple since we never need a combo CID */
     398             : #define HeapTupleHeaderSetCmin(tup, cid) \
     399             : do { \
     400             :     Assert(!((tup)->t_infomask & HEAP_MOVED)); \
     401             :     (tup)->t_choice.t_heap.t_field3.t_cid = (cid); \
     402             :     (tup)->t_infomask &= ~HEAP_COMBOCID; \
     403             : } while (0)
     404             : 
     405             : /* SetCmax must be used after HeapTupleHeaderAdjustCmax; see combocid.c */
     406             : #define HeapTupleHeaderSetCmax(tup, cid, iscombo) \
     407             : do { \
     408             :     Assert(!((tup)->t_infomask & HEAP_MOVED)); \
     409             :     (tup)->t_choice.t_heap.t_field3.t_cid = (cid); \
     410             :     if (iscombo) \
     411             :         (tup)->t_infomask |= HEAP_COMBOCID; \
     412             :     else \
     413             :         (tup)->t_infomask &= ~HEAP_COMBOCID; \
     414             : } while (0)
     415             : 
     416             : #define HeapTupleHeaderGetXvac(tup) \
     417             : ( \
     418             :     ((tup)->t_infomask & HEAP_MOVED) ? \
     419             :         (tup)->t_choice.t_heap.t_field3.t_xvac \
     420             :     : \
     421             :         InvalidTransactionId \
     422             : )
     423             : 
     424             : #define HeapTupleHeaderSetXvac(tup, xid) \
     425             : do { \
     426             :     Assert((tup)->t_infomask & HEAP_MOVED); \
     427             :     (tup)->t_choice.t_heap.t_field3.t_xvac = (xid); \
     428             : } while (0)
     429             : 
     430             : StaticAssertDecl(MaxOffsetNumber < SpecTokenOffsetNumber,
     431             :                  "invalid speculative token constant");
     432             : 
     433             : #define HeapTupleHeaderIsSpeculative(tup) \
     434             : ( \
     435             :     (ItemPointerGetOffsetNumberNoCheck(&(tup)->t_ctid) == SpecTokenOffsetNumber) \
     436             : )
     437             : 
     438             : #define HeapTupleHeaderGetSpeculativeToken(tup) \
     439             : ( \
     440             :     AssertMacro(HeapTupleHeaderIsSpeculative(tup)), \
     441             :     ItemPointerGetBlockNumber(&(tup)->t_ctid) \
     442             : )
     443             : 
     444             : #define HeapTupleHeaderSetSpeculativeToken(tup, token)  \
     445             : ( \
     446             :     ItemPointerSet(&(tup)->t_ctid, token, SpecTokenOffsetNumber) \
     447             : )
     448             : 
     449             : #define HeapTupleHeaderIndicatesMovedPartitions(tup) \
     450             :     ItemPointerIndicatesMovedPartitions(&(tup)->t_ctid)
     451             : 
     452             : #define HeapTupleHeaderSetMovedPartitions(tup) \
     453             :     ItemPointerSetMovedPartitions(&(tup)->t_ctid)
     454             : 
     455             : #define HeapTupleHeaderGetDatumLength(tup) \
     456             :     VARSIZE(tup)
     457             : 
     458             : #define HeapTupleHeaderSetDatumLength(tup, len) \
     459             :     SET_VARSIZE(tup, len)
     460             : 
     461             : #define HeapTupleHeaderGetTypeId(tup) \
     462             : ( \
     463             :     (tup)->t_choice.t_datum.datum_typeid \
     464             : )
     465             : 
     466             : #define HeapTupleHeaderSetTypeId(tup, typeid) \
     467             : ( \
     468             :     (tup)->t_choice.t_datum.datum_typeid = (typeid) \
     469             : )
     470             : 
     471             : #define HeapTupleHeaderGetTypMod(tup) \
     472             : ( \
     473             :     (tup)->t_choice.t_datum.datum_typmod \
     474             : )
     475             : 
     476             : #define HeapTupleHeaderSetTypMod(tup, typmod) \
     477             : ( \
     478             :     (tup)->t_choice.t_datum.datum_typmod = (typmod) \
     479             : )
     480             : 
     481             : /*
     482             :  * Note that we stop considering a tuple HOT-updated as soon as it is known
     483             :  * aborted or the would-be updating transaction is known aborted.  For best
     484             :  * efficiency, check tuple visibility before using this macro, so that the
     485             :  * INVALID bits will be as up to date as possible.
     486             :  */
     487             : #define HeapTupleHeaderIsHotUpdated(tup) \
     488             : ( \
     489             :     ((tup)->t_infomask2 & HEAP_HOT_UPDATED) != 0 && \
     490             :     ((tup)->t_infomask & HEAP_XMAX_INVALID) == 0 && \
     491             :     !HeapTupleHeaderXminInvalid(tup) \
     492             : )
     493             : 
     494             : #define HeapTupleHeaderSetHotUpdated(tup) \
     495             : ( \
     496             :     (tup)->t_infomask2 |= HEAP_HOT_UPDATED \
     497             : )
     498             : 
     499             : #define HeapTupleHeaderClearHotUpdated(tup) \
     500             : ( \
     501             :     (tup)->t_infomask2 &= ~HEAP_HOT_UPDATED \
     502             : )
     503             : 
     504             : #define HeapTupleHeaderIsHeapOnly(tup) \
     505             : ( \
     506             :   ((tup)->t_infomask2 & HEAP_ONLY_TUPLE) != 0 \
     507             : )
     508             : 
     509             : #define HeapTupleHeaderSetHeapOnly(tup) \
     510             : ( \
     511             :   (tup)->t_infomask2 |= HEAP_ONLY_TUPLE \
     512             : )
     513             : 
     514             : #define HeapTupleHeaderClearHeapOnly(tup) \
     515             : ( \
     516             :   (tup)->t_infomask2 &= ~HEAP_ONLY_TUPLE \
     517             : )
     518             : 
     519             : #define HeapTupleHeaderHasMatch(tup) \
     520             : ( \
     521             :   ((tup)->t_infomask2 & HEAP_TUPLE_HAS_MATCH) != 0 \
     522             : )
     523             : 
     524             : #define HeapTupleHeaderSetMatch(tup) \
     525             : ( \
     526             :   (tup)->t_infomask2 |= HEAP_TUPLE_HAS_MATCH \
     527             : )
     528             : 
     529             : #define HeapTupleHeaderClearMatch(tup) \
     530             : ( \
     531             :   (tup)->t_infomask2 &= ~HEAP_TUPLE_HAS_MATCH \
     532             : )
     533             : 
     534             : #define HeapTupleHeaderGetNatts(tup) \
     535             :     ((tup)->t_infomask2 & HEAP_NATTS_MASK)
     536             : 
     537             : #define HeapTupleHeaderSetNatts(tup, natts) \
     538             : ( \
     539             :     (tup)->t_infomask2 = ((tup)->t_infomask2 & ~HEAP_NATTS_MASK) | (natts) \
     540             : )
     541             : 
     542             : #define HeapTupleHeaderHasExternal(tup) \
     543             :         (((tup)->t_infomask & HEAP_HASEXTERNAL) != 0)
     544             : 
     545             : 
     546             : /*
     547             :  * BITMAPLEN(NATTS) -
     548             :  *      Computes size of null bitmap given number of data columns.
     549             :  */
     550             : #define BITMAPLEN(NATTS)    (((int)(NATTS) + 7) / 8)
     551             : 
     552             : /*
     553             :  * MaxHeapTupleSize is the maximum allowed size of a heap tuple, including
     554             :  * header and MAXALIGN alignment padding.  Basically it's BLCKSZ minus the
     555             :  * other stuff that has to be on a disk page.  Since heap pages use no
     556             :  * "special space", there's no deduction for that.
     557             :  *
     558             :  * NOTE: we allow for the ItemId that must point to the tuple, ensuring that
     559             :  * an otherwise-empty page can indeed hold a tuple of this size.  Because
     560             :  * ItemIds and tuples have different alignment requirements, don't assume that
     561             :  * you can, say, fit 2 tuples of size MaxHeapTupleSize/2 on the same page.
     562             :  */
     563             : #define MaxHeapTupleSize  (BLCKSZ - MAXALIGN(SizeOfPageHeaderData + sizeof(ItemIdData)))
     564             : #define MinHeapTupleSize  MAXALIGN(SizeofHeapTupleHeader)
     565             : 
     566             : /*
     567             :  * MaxHeapTuplesPerPage is an upper bound on the number of tuples that can
     568             :  * fit on one heap page.  (Note that indexes could have more, because they
     569             :  * use a smaller tuple header.)  We arrive at the divisor because each tuple
     570             :  * must be maxaligned, and it must have an associated line pointer.
     571             :  *
     572             :  * Note: with HOT, there could theoretically be more line pointers (not actual
     573             :  * tuples) than this on a heap page.  However we constrain the number of line
     574             :  * pointers to this anyway, to avoid excessive line-pointer bloat and not
     575             :  * require increases in the size of work arrays.
     576             :  */
     577             : #define MaxHeapTuplesPerPage    \
     578             :     ((int) ((BLCKSZ - SizeOfPageHeaderData) / \
     579             :             (MAXALIGN(SizeofHeapTupleHeader) + sizeof(ItemIdData))))
     580             : 
     581             : /*
     582             :  * MaxAttrSize is a somewhat arbitrary upper limit on the declared size of
     583             :  * data fields of char(n) and similar types.  It need not have anything
     584             :  * directly to do with the *actual* upper limit of varlena values, which
     585             :  * is currently 1Gb (see TOAST structures in postgres.h).  I've set it
     586             :  * at 10Mb which seems like a reasonable number --- tgl 8/6/00.
     587             :  */
     588             : #define MaxAttrSize     (10 * 1024 * 1024)
     589             : 
     590             : 
     591             : /*
     592             :  * MinimalTuple is an alternative representation that is used for transient
     593             :  * tuples inside the executor, in places where transaction status information
     594             :  * is not required, the tuple rowtype is known, and shaving off a few bytes
     595             :  * is worthwhile because we need to store many tuples.  The representation
     596             :  * is chosen so that tuple access routines can work with either full or
     597             :  * minimal tuples via a HeapTupleData pointer structure.  The access routines
     598             :  * see no difference, except that they must not access the transaction status
     599             :  * or t_ctid fields because those aren't there.
     600             :  *
     601             :  * For the most part, MinimalTuples should be accessed via TupleTableSlot
     602             :  * routines.  These routines will prevent access to the "system columns"
     603             :  * and thereby prevent accidental use of the nonexistent fields.
     604             :  *
     605             :  * MinimalTupleData contains a length word, some padding, and fields matching
     606             :  * HeapTupleHeaderData beginning with t_infomask2. The padding is chosen so
     607             :  * that offsetof(t_infomask2) is the same modulo MAXIMUM_ALIGNOF in both
     608             :  * structs.   This makes data alignment rules equivalent in both cases.
     609             :  *
     610             :  * When a minimal tuple is accessed via a HeapTupleData pointer, t_data is
     611             :  * set to point MINIMAL_TUPLE_OFFSET bytes before the actual start of the
     612             :  * minimal tuple --- that is, where a full tuple matching the minimal tuple's
     613             :  * data would start.  This trick is what makes the structs seem equivalent.
     614             :  *
     615             :  * Note that t_hoff is computed the same as in a full tuple, hence it includes
     616             :  * the MINIMAL_TUPLE_OFFSET distance.  t_len does not include that, however.
     617             :  *
     618             :  * MINIMAL_TUPLE_DATA_OFFSET is the offset to the first useful (non-pad) data
     619             :  * other than the length word.  tuplesort.c and tuplestore.c use this to avoid
     620             :  * writing the padding to disk.
     621             :  */
     622             : #define MINIMAL_TUPLE_OFFSET \
     623             :     ((offsetof(HeapTupleHeaderData, t_infomask2) - sizeof(uint32)) / MAXIMUM_ALIGNOF * MAXIMUM_ALIGNOF)
     624             : #define MINIMAL_TUPLE_PADDING \
     625             :     ((offsetof(HeapTupleHeaderData, t_infomask2) - sizeof(uint32)) % MAXIMUM_ALIGNOF)
     626             : #define MINIMAL_TUPLE_DATA_OFFSET \
     627             :     offsetof(MinimalTupleData, t_infomask2)
     628             : 
     629             : struct MinimalTupleData
     630             : {
     631             :     uint32      t_len;          /* actual length of minimal tuple */
     632             : 
     633             :     char        mt_padding[MINIMAL_TUPLE_PADDING];
     634             : 
     635             :     /* Fields below here must match HeapTupleHeaderData! */
     636             : 
     637             :     uint16      t_infomask2;    /* number of attributes + various flags */
     638             : 
     639             :     uint16      t_infomask;     /* various flag bits, see below */
     640             : 
     641             :     uint8       t_hoff;         /* sizeof header incl. bitmap, padding */
     642             : 
     643             :     /* ^ - 23 bytes - ^ */
     644             : 
     645             :     bits8       t_bits[FLEXIBLE_ARRAY_MEMBER];  /* bitmap of NULLs */
     646             : 
     647             :     /* MORE DATA FOLLOWS AT END OF STRUCT */
     648             : };
     649             : 
     650             : /* typedef appears in htup.h */
     651             : 
     652             : #define SizeofMinimalTupleHeader offsetof(MinimalTupleData, t_bits)
     653             : 
     654             : 
     655             : /*
     656             :  * GETSTRUCT - given a HeapTuple pointer, return address of the user data
     657             :  */
     658             : #define GETSTRUCT(TUP) ((char *) ((TUP)->t_data) + (TUP)->t_data->t_hoff)
     659             : 
     660             : /*
     661             :  * Accessor macros to be used with HeapTuple pointers.
     662             :  */
     663             : 
     664             : #define HeapTupleHasNulls(tuple) \
     665             :         (((tuple)->t_data->t_infomask & HEAP_HASNULL) != 0)
     666             : 
     667             : #define HeapTupleNoNulls(tuple) \
     668             :         (!((tuple)->t_data->t_infomask & HEAP_HASNULL))
     669             : 
     670             : #define HeapTupleHasVarWidth(tuple) \
     671             :         (((tuple)->t_data->t_infomask & HEAP_HASVARWIDTH) != 0)
     672             : 
     673             : #define HeapTupleAllFixed(tuple) \
     674             :         (!((tuple)->t_data->t_infomask & HEAP_HASVARWIDTH))
     675             : 
     676             : #define HeapTupleHasExternal(tuple) \
     677             :         (((tuple)->t_data->t_infomask & HEAP_HASEXTERNAL) != 0)
     678             : 
     679             : #define HeapTupleIsHotUpdated(tuple) \
     680             :         HeapTupleHeaderIsHotUpdated((tuple)->t_data)
     681             : 
     682             : #define HeapTupleSetHotUpdated(tuple) \
     683             :         HeapTupleHeaderSetHotUpdated((tuple)->t_data)
     684             : 
     685             : #define HeapTupleClearHotUpdated(tuple) \
     686             :         HeapTupleHeaderClearHotUpdated((tuple)->t_data)
     687             : 
     688             : #define HeapTupleIsHeapOnly(tuple) \
     689             :         HeapTupleHeaderIsHeapOnly((tuple)->t_data)
     690             : 
     691             : #define HeapTupleSetHeapOnly(tuple) \
     692             :         HeapTupleHeaderSetHeapOnly((tuple)->t_data)
     693             : 
     694             : #define HeapTupleClearHeapOnly(tuple) \
     695             :         HeapTupleHeaderClearHeapOnly((tuple)->t_data)
     696             : 
     697             : /* prototypes for functions in common/heaptuple.c */
     698             : extern Size heap_compute_data_size(TupleDesc tupleDesc,
     699             :                                    const Datum *values, const bool *isnull);
     700             : extern void heap_fill_tuple(TupleDesc tupleDesc,
     701             :                             const Datum *values, const bool *isnull,
     702             :                             char *data, Size data_size,
     703             :                             uint16 *infomask, bits8 *bit);
     704             : extern bool heap_attisnull(HeapTuple tup, int attnum, TupleDesc tupleDesc);
     705             : extern Datum nocachegetattr(HeapTuple tup, int attnum,
     706             :                             TupleDesc tupleDesc);
     707             : extern Datum heap_getsysattr(HeapTuple tup, int attnum, TupleDesc tupleDesc,
     708             :                              bool *isnull);
     709             : extern Datum getmissingattr(TupleDesc tupleDesc,
     710             :                             int attnum, bool *isnull);
     711             : extern HeapTuple heap_copytuple(HeapTuple tuple);
     712             : extern void heap_copytuple_with_tuple(HeapTuple src, HeapTuple dest);
     713             : extern Datum heap_copy_tuple_as_datum(HeapTuple tuple, TupleDesc tupleDesc);
     714             : extern HeapTuple heap_form_tuple(TupleDesc tupleDescriptor,
     715             :                                  const Datum *values, const bool *isnull);
     716             : extern HeapTuple heap_modify_tuple(HeapTuple tuple,
     717             :                                    TupleDesc tupleDesc,
     718             :                                    const Datum *replValues,
     719             :                                    const bool *replIsnull,
     720             :                                    const bool *doReplace);
     721             : extern HeapTuple heap_modify_tuple_by_cols(HeapTuple tuple,
     722             :                                            TupleDesc tupleDesc,
     723             :                                            int nCols,
     724             :                                            const int *replCols,
     725             :                                            const Datum *replValues,
     726             :                                            const bool *replIsnull);
     727             : extern void heap_deform_tuple(HeapTuple tuple, TupleDesc tupleDesc,
     728             :                               Datum *values, bool *isnull);
     729             : extern void heap_freetuple(HeapTuple htup);
     730             : extern MinimalTuple heap_form_minimal_tuple(TupleDesc tupleDescriptor,
     731             :                                             const Datum *values, const bool *isnull);
     732             : extern void heap_free_minimal_tuple(MinimalTuple mtup);
     733             : extern MinimalTuple heap_copy_minimal_tuple(MinimalTuple mtup);
     734             : extern HeapTuple heap_tuple_from_minimal_tuple(MinimalTuple mtup);
     735             : extern MinimalTuple minimal_tuple_from_heap_tuple(HeapTuple htup);
     736             : extern size_t varsize_any(void *p);
     737             : extern HeapTuple heap_expand_tuple(HeapTuple sourceTuple, TupleDesc tupleDesc);
     738             : extern MinimalTuple minimal_expand_tuple(HeapTuple sourceTuple, TupleDesc tupleDesc);
     739             : 
     740             : #ifndef FRONTEND
     741             : /*
     742             :  *  fastgetattr
     743             :  *      Fetch a user attribute's value as a Datum (might be either a
     744             :  *      value, or a pointer into the data area of the tuple).
     745             :  *
     746             :  *      This must not be used when a system attribute might be requested.
     747             :  *      Furthermore, the passed attnum MUST be valid.  Use heap_getattr()
     748             :  *      instead, if in doubt.
     749             :  *
     750             :  *      This gets called many times, so we macro the cacheable and NULL
     751             :  *      lookups, and call nocachegetattr() for the rest.
     752             :  */
     753             : static inline Datum
     754   234052756 : fastgetattr(HeapTuple tup, int attnum, TupleDesc tupleDesc, bool *isnull)
     755             : {
     756             :     Assert(attnum > 0);
     757             : 
     758   234052756 :     *isnull = false;
     759   234052756 :     if (HeapTupleNoNulls(tup))
     760             :     {
     761             :         Form_pg_attribute att;
     762             : 
     763   105722228 :         att = TupleDescAttr(tupleDesc, attnum - 1);
     764   105722228 :         if (att->attcacheoff >= 0)
     765    63807036 :             return fetchatt(att, (char *) tup->t_data + tup->t_data->t_hoff +
     766             :                             att->attcacheoff);
     767             :         else
     768    41915192 :             return nocachegetattr(tup, attnum, tupleDesc);
     769             :     }
     770             :     else
     771             :     {
     772   128330528 :         if (att_isnull(attnum - 1, tup->t_data->t_bits))
     773             :         {
     774    15361148 :             *isnull = true;
     775    15361148 :             return (Datum) NULL;
     776             :         }
     777             :         else
     778   112969380 :             return nocachegetattr(tup, attnum, tupleDesc);
     779             :     }
     780             : }
     781             : 
     782             : /*
     783             :  *  heap_getattr
     784             :  *      Extract an attribute of a heap tuple and return it as a Datum.
     785             :  *      This works for either system or user attributes.  The given attnum
     786             :  *      is properly range-checked.
     787             :  *
     788             :  *      If the field in question has a NULL value, we return a zero Datum
     789             :  *      and set *isnull == true.  Otherwise, we set *isnull == false.
     790             :  *
     791             :  *      <tup> is the pointer to the heap tuple.  <attnum> is the attribute
     792             :  *      number of the column (field) caller wants.  <tupleDesc> is a
     793             :  *      pointer to the structure describing the row and all its fields.
     794             :  *
     795             :  */
     796             : static inline Datum
     797   219601312 : heap_getattr(HeapTuple tup, int attnum, TupleDesc tupleDesc, bool *isnull)
     798             : {
     799   219601312 :     if (attnum > 0)
     800             :     {
     801   219601312 :         if (attnum > (int) HeapTupleHeaderGetNatts(tup->t_data))
     802         332 :             return getmissingattr(tupleDesc, attnum, isnull);
     803             :         else
     804   219600980 :             return fastgetattr(tup, attnum, tupleDesc, isnull);
     805             :     }
     806             :     else
     807           0 :         return heap_getsysattr(tup, attnum, tupleDesc, isnull);
     808             : }
     809             : #endif                          /* FRONTEND */
     810             : 
     811             : #endif                          /* HTUP_DETAILS_H */

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