granicus.if.org Git - postgresql/blob - src/backend/access/index/indexam.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * indexam.c
   4  *        general index access method routines
   5  *
   6  * Portions Copyright (c) 1996-2011, 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_getnext_tid       - get the next TID from a scan
  24  *              index_fetch_heap                - get the scan's next heap tuple
  25  *              index_getnext   - get the next heap tuple from a scan
  26  *              index_getbitmap - get all tuples from a scan
  27  *              index_bulk_delete       - bulk deletion of index tuples
  28  *              index_vacuum_cleanup    - post-deletion cleanup of an index
  29  *              index_getprocid - get a support procedure OID
  30  *              index_getprocinfo - get a support procedure's lookup info
  31  *
  32  * NOTES
  33  *              This file contains the index_ routines which used
  34  *              to be a scattered collection of stuff in access/genam.
  35  *
  36  *
  37  * old comments
  38  *              Scans are implemented as follows:
  39  *
  40  *              `0' represents an invalid item pointer.
  41  *              `-' represents an unknown item pointer.
  42  *              `X' represents a known item pointers.
  43  *              `+' represents known or invalid item pointers.
  44  *              `*' represents any item pointers.
  45  *
  46  *              State is represented by a triple of these symbols in the order of
  47  *              previous, current, next.  Note that the case of reverse scans works
  48  *              identically.
  49  *
  50  *                              State   Result
  51  *              (1)             + + -   + 0 0                   (if the next item pointer is invalid)
  52  *              (2)                             + X -                   (otherwise)
  53  *              (3)             * 0 0   * 0 0                   (no change)
  54  *              (4)             + X 0   X 0 0                   (shift)
  55  *              (5)             * + X   + X -                   (shift, add unknown)
  56  *
  57  *              All other states cannot occur.
  58  *
  59  *              Note: It would be possible to cache the status of the previous and
  60  *                        next item pointer using the flags.
  61  *
  62  *-------------------------------------------------------------------------
  63  */
  64
  65 #include "postgres.h"
  66
  67 #include "access/relscan.h"
  68 #include "access/transam.h"
  69 #include "catalog/index.h"
  70 #include "pgstat.h"
  71 #include "storage/bufmgr.h"
  72 #include "storage/lmgr.h"
  73 #include "storage/predicate.h"
  74 #include "utils/snapmgr.h"
  75 #include "utils/tqual.h"
  76
  77
  78 /* ----------------------------------------------------------------
  79  *                                      macros used in index_ routines
  80  *
  81  * Note: the ReindexIsProcessingIndex() check in RELATION_CHECKS is there
  82  * to check that we don't try to scan or do retail insertions into an index
  83  * that is currently being rebuilt or pending rebuild.  This helps to catch
  84  * things that don't work when reindexing system catalogs.  The assertion
  85  * doesn't prevent the actual rebuild because we don't use RELATION_CHECKS
  86  * when calling the index AM's ambuild routine, and there is no reason for
  87  * ambuild to call its subsidiary routines through this file.
  88  * ----------------------------------------------------------------
  89  */
  90 #define RELATION_CHECKS \
  91 ( \
  92         AssertMacro(RelationIsValid(indexRelation)), \
  93         AssertMacro(PointerIsValid(indexRelation->rd_am)), \
  94         AssertMacro(!ReindexIsProcessingIndex(RelationGetRelid(indexRelation))) \
  95 )
  96
  97 #define SCAN_CHECKS \
  98 ( \
  99         AssertMacro(IndexScanIsValid(scan)), \
 100         AssertMacro(RelationIsValid(scan->indexRelation)), \
 101         AssertMacro(PointerIsValid(scan->indexRelation->rd_am)) \
 102 )
 103
 104 #define GET_REL_PROCEDURE(pname) \
 105 do { \
 106         procedure = &indexRelation->rd_aminfo->pname; \
 107         if (!OidIsValid(procedure->fn_oid)) \
 108         { \
 109                 RegProcedure    procOid = indexRelation->rd_am->pname; \
 110                 if (!RegProcedureIsValid(procOid)) \
 111                         elog(ERROR, "invalid %s regproc", CppAsString(pname)); \
 112                 fmgr_info_cxt(procOid, procedure, indexRelation->rd_indexcxt); \
 113         } \
 114 } while(0)
 115
 116 #define GET_SCAN_PROCEDURE(pname) \
 117 do { \
 118         procedure = &scan->indexRelation->rd_aminfo->pname; \
 119         if (!OidIsValid(procedure->fn_oid)) \
 120         { \
 121                 RegProcedure    procOid = scan->indexRelation->rd_am->pname; \
 122                 if (!RegProcedureIsValid(procOid)) \
 123                         elog(ERROR, "invalid %s regproc", CppAsString(pname)); \
 124                 fmgr_info_cxt(procOid, procedure, scan->indexRelation->rd_indexcxt); \
 125         } \
 126 } while(0)
 127
 128 static IndexScanDesc index_beginscan_internal(Relation indexRelation,
 129                                                  int nkeys, int norderbys, Snapshot snapshot);
 130
 131
 132 /* ----------------------------------------------------------------
 133  *                                 index_ interface functions
 134  * ----------------------------------------------------------------
 135  */
 136
 137 /* ----------------
 138  *              index_open - open an index relation by relation OID
 139  *
 140  *              If lockmode is not "NoLock", the specified kind of lock is
 141  *              obtained on the index.  (Generally, NoLock should only be
 142  *              used if the caller knows it has some appropriate lock on the
 143  *              index already.)
 144  *
 145  *              An error is raised if the index does not exist.
 146  *
 147  *              This is a convenience routine adapted for indexscan use.
 148  *              Some callers may prefer to use relation_open directly.
 149  * ----------------
 150  */
 151 Relation
 152 index_open(Oid relationId, LOCKMODE lockmode)
 153 {
 154         Relation        r;
 155
 156         r = relation_open(relationId, lockmode);
 157
 158         if (r->rd_rel->relkind != RELKIND_INDEX)
 159                 ereport(ERROR,
 160                                 (errcode(ERRCODE_WRONG_OBJECT_TYPE),
 161                                  errmsg("\"%s\" is not an index",
 162                                                 RelationGetRelationName(r))));
 163
 164         return r;
 165 }
 166
 167 /* ----------------
 168  *              index_close - close an index relation
 169  *
 170  *              If lockmode is not "NoLock", we then release the specified lock.
 171  *
 172  *              Note that it is often sensible to hold a lock beyond index_close;
 173  *              in that case, the lock is released automatically at xact end.
 174  * ----------------
 175  */
 176 void
 177 index_close(Relation relation, LOCKMODE lockmode)
 178 {
 179         LockRelId       relid = relation->rd_lockInfo.lockRelId;
 180
 181         Assert(lockmode >= NoLock && lockmode < MAX_LOCKMODES);
 182
 183         /* The relcache does the real work... */
 184         RelationClose(relation);
 185
 186         if (lockmode != NoLock)
 187                 UnlockRelationId(&relid, lockmode);
 188 }
 189
 190 /* ----------------
 191  *              index_insert - insert an index tuple into a relation
 192  * ----------------
 193  */
 194 bool
 195 index_insert(Relation indexRelation,
 196                          Datum *values,
 197                          bool *isnull,
 198                          ItemPointer heap_t_ctid,
 199                          Relation heapRelation,
 200                          IndexUniqueCheck checkUnique)
 201 {
 202         FmgrInfo   *procedure;
 203
 204         RELATION_CHECKS;
 205         GET_REL_PROCEDURE(aminsert);
 206
 207         if (!(indexRelation->rd_am->ampredlocks))
 208                 CheckForSerializableConflictIn(indexRelation,
 209                                                                            (HeapTuple) NULL,
 210                                                                            InvalidBuffer);
 211
 212         /*
 213          * have the am's insert proc do all the work.
 214          */
 215         return DatumGetBool(FunctionCall6(procedure,
 216                                                                           PointerGetDatum(indexRelation),
 217                                                                           PointerGetDatum(values),
 218                                                                           PointerGetDatum(isnull),
 219                                                                           PointerGetDatum(heap_t_ctid),
 220                                                                           PointerGetDatum(heapRelation),
 221                                                                           Int32GetDatum((int32) checkUnique)));
 222 }
 223
 224 /*
 225  * index_beginscan - start a scan of an index with amgettuple
 226  *
 227  * Caller must be holding suitable locks on the heap and the index.
 228  */
 229 IndexScanDesc
 230 index_beginscan(Relation heapRelation,
 231                                 Relation indexRelation,
 232                                 Snapshot snapshot,
 233                                 int nkeys, int norderbys)
 234 {
 235         IndexScanDesc scan;
 236
 237         scan = index_beginscan_internal(indexRelation, nkeys, norderbys, snapshot);
 238
 239         /*
 240          * Save additional parameters into the scandesc.  Everything else was set
 241          * up by RelationGetIndexScan.
 242          */
 243         scan->heapRelation = heapRelation;
 244         scan->xs_snapshot = snapshot;
 245
 246         return scan;
 247 }
 248
 249 /*
 250  * index_beginscan_bitmap - start a scan of an index with amgetbitmap
 251  *
 252  * As above, caller had better be holding some lock on the parent heap
 253  * relation, even though it's not explicitly mentioned here.
 254  */
 255 IndexScanDesc
 256 index_beginscan_bitmap(Relation indexRelation,
 257                                            Snapshot snapshot,
 258                                            int nkeys)
 259 {
 260         IndexScanDesc scan;
 261
 262         scan = index_beginscan_internal(indexRelation, nkeys, 0, snapshot);
 263
 264         /*
 265          * Save additional parameters into the scandesc.  Everything else was set
 266          * up by RelationGetIndexScan.
 267          */
 268         scan->xs_snapshot = snapshot;
 269
 270         return scan;
 271 }
 272
 273 /*
 274  * index_beginscan_internal --- common code for index_beginscan variants
 275  */
 276 static IndexScanDesc
 277 index_beginscan_internal(Relation indexRelation,
 278                                                  int nkeys, int norderbys, Snapshot snapshot)
 279 {
 280         IndexScanDesc scan;
 281         FmgrInfo   *procedure;
 282
 283         RELATION_CHECKS;
 284         GET_REL_PROCEDURE(ambeginscan);
 285
 286         if (!(indexRelation->rd_am->ampredlocks))
 287                 PredicateLockRelation(indexRelation, snapshot);
 288
 289         /*
 290          * We hold a reference count to the relcache entry throughout the scan.
 291          */
 292         RelationIncrementReferenceCount(indexRelation);
 293
 294         /*
 295          * Tell the AM to open a scan.
 296          */
 297         scan = (IndexScanDesc)
 298                 DatumGetPointer(FunctionCall3(procedure,
 299                                                                           PointerGetDatum(indexRelation),
 300                                                                           Int32GetDatum(nkeys),
 301                                                                           Int32GetDatum(norderbys)));
 302
 303         return scan;
 304 }
 305
 306 /* ----------------
 307  *              index_rescan  - (re)start a scan of an index
 308  *
 309  * During a restart, the caller may specify a new set of scankeys and/or
 310  * orderbykeys; but the number of keys cannot differ from what index_beginscan
 311  * was told.  (Later we might relax that to "must not exceed", but currently
 312  * the index AMs tend to assume that scan->numberOfKeys is what to believe.)
 313  * To restart the scan without changing keys, pass NULL for the key arrays.
 314  * (Of course, keys *must* be passed on the first call, unless
 315  * scan->numberOfKeys is zero.)
 316  * ----------------
 317  */
 318 void
 319 index_rescan(IndexScanDesc scan,
 320                          ScanKey keys, int nkeys,
 321                          ScanKey orderbys, int norderbys)
 322 {
 323         FmgrInfo   *procedure;
 324
 325         SCAN_CHECKS;
 326         GET_SCAN_PROCEDURE(amrescan);
 327
 328         Assert(nkeys == scan->numberOfKeys);
 329         Assert(norderbys == scan->numberOfOrderBys);
 330
 331         /* Release any held pin on a heap page */
 332         if (BufferIsValid(scan->xs_cbuf))
 333         {
 334                 ReleaseBuffer(scan->xs_cbuf);
 335                 scan->xs_cbuf = InvalidBuffer;
 336         }
 337
 338         scan->xs_continue_hot = false;
 339
 340         scan->kill_prior_tuple = false;         /* for safety */
 341
 342         FunctionCall5(procedure,
 343                                   PointerGetDatum(scan),
 344                                   PointerGetDatum(keys),
 345                                   Int32GetDatum(nkeys),
 346                                   PointerGetDatum(orderbys),
 347                                   Int32GetDatum(norderbys));
 348 }
 349
 350 /* ----------------
 351  *              index_endscan - end a scan
 352  * ----------------
 353  */
 354 void
 355 index_endscan(IndexScanDesc scan)
 356 {
 357         FmgrInfo   *procedure;
 358
 359         SCAN_CHECKS;
 360         GET_SCAN_PROCEDURE(amendscan);
 361
 362         /* Release any held pin on a heap page */
 363         if (BufferIsValid(scan->xs_cbuf))
 364         {
 365                 ReleaseBuffer(scan->xs_cbuf);
 366                 scan->xs_cbuf = InvalidBuffer;
 367         }
 368
 369         /* End the AM's scan */
 370         FunctionCall1(procedure, PointerGetDatum(scan));
 371
 372         /* Release index refcount acquired by index_beginscan */
 373         RelationDecrementReferenceCount(scan->indexRelation);
 374
 375         /* Release the scan data structure itself */
 376         IndexScanEnd(scan);
 377 }
 378
 379 /* ----------------
 380  *              index_markpos  - mark a scan position
 381  * ----------------
 382  */
 383 void
 384 index_markpos(IndexScanDesc scan)
 385 {
 386         FmgrInfo   *procedure;
 387
 388         SCAN_CHECKS;
 389         GET_SCAN_PROCEDURE(ammarkpos);
 390
 391         FunctionCall1(procedure, PointerGetDatum(scan));
 392 }
 393
 394 /* ----------------
 395  *              index_restrpos  - restore a scan position
 396  *
 397  * NOTE: this only restores the internal scan state of the index AM.
 398  * The current result tuple (scan->xs_ctup) doesn't change.  See comments
 399  * for ExecRestrPos().
 400  *
 401  * NOTE: in the presence of HOT chains, mark/restore only works correctly
 402  * if the scan's snapshot is MVCC-safe; that ensures that there's at most one
 403  * returnable tuple in each HOT chain, and so restoring the prior state at the
 404  * granularity of the index AM is sufficient.  Since the only current user
 405  * of mark/restore functionality is nodeMergejoin.c, this effectively means
 406  * that merge-join plans only work for MVCC snapshots.  This could be fixed
 407  * if necessary, but for now it seems unimportant.
 408  * ----------------
 409  */
 410 void
 411 index_restrpos(IndexScanDesc scan)
 412 {
 413         FmgrInfo   *procedure;
 414
 415         Assert(IsMVCCSnapshot(scan->xs_snapshot));
 416
 417         SCAN_CHECKS;
 418         GET_SCAN_PROCEDURE(amrestrpos);
 419
 420         scan->xs_continue_hot = false;
 421
 422         scan->kill_prior_tuple = false;         /* for safety */
 423
 424         FunctionCall1(procedure, PointerGetDatum(scan));
 425 }
 426
 427 /* ----------------
 428  * index_getnext_tid - get the next TID from a scan
 429  *
 430  * The result is the next TID satisfying the scan keys,
 431  * or NULL if no more matching tuples exist.
 432  * ----------------
 433  */
 434 ItemPointer
 435 index_getnext_tid(IndexScanDesc scan, ScanDirection direction)
 436 {
 437         FmgrInfo        *procedure;
 438         bool            found;
 439
 440         SCAN_CHECKS;
 441         GET_SCAN_PROCEDURE(amgettuple);
 442
 443         Assert(TransactionIdIsValid(RecentGlobalXmin));
 444
 445         /*
 446          * The AM's amgettuple proc finds the next index entry matching the scan
 447          * keys, and puts the TID into scan->xs_ctup.t_self.  It should also set
 448          * scan->xs_recheck and possibly scan->xs_itup, though we pay no attention
 449          * to those fields here.
 450          */
 451         found = DatumGetBool(FunctionCall2(procedure,
 452                                                                            PointerGetDatum(scan),
 453                                                                            Int32GetDatum(direction)));
 454
 455         /* Reset kill flag immediately for safety */
 456         scan->kill_prior_tuple = false;
 457
 458         /* If we're out of index entries, we're done */
 459         if (!found)
 460         {
 461                 /* ... but first, release any held pin on a heap page */
 462                 if (BufferIsValid(scan->xs_cbuf))
 463                 {
 464                         ReleaseBuffer(scan->xs_cbuf);
 465                         scan->xs_cbuf = InvalidBuffer;
 466                 }
 467                 return NULL;
 468         }
 469
 470         pgstat_count_index_tuples(scan->indexRelation, 1);
 471
 472         /* Return the TID of the tuple we found. */
 473         return &scan->xs_ctup.t_self;
 474 }
 475
 476 /* ----------------
 477  *              index_fetch_heap - get the scan's next heap tuple
 478  *
 479  * The result is a visible heap tuple associated with the index TID most
 480  * recently fetched by index_getnext_tid, or NULL if no more matching tuples
 481  * exist.  (There can be more than one matching tuple because of HOT chains,
 482  * although when using an MVCC snapshot it should be impossible for more than
 483  * one such tuple to exist.)
 484  *
 485  * On success, the buffer containing the heap tup is pinned (the pin will be
 486  * dropped in a future index_getnext_tid, index_fetch_heap or index_endscan
 487  * call).
 488  *
 489  * Note: caller must check scan->xs_recheck, and perform rechecking of the
 490  * scan keys if required.  We do not do that here because we don't have
 491  * enough information to do it efficiently in the general case.
 492  * ----------------
 493  */
 494 HeapTuple
 495 index_fetch_heap(IndexScanDesc scan)
 496 {
 497         ItemPointer     tid = &scan->xs_ctup.t_self;
 498         bool            all_dead = false;
 499         bool            got_heap_tuple;
 500
 501         /* We can skip the buffer-switching logic if we're in mid-HOT chain. */
 502         if (!scan->xs_continue_hot)
 503         {
 504                 /* Switch to correct buffer if we don't have it already */
 505                 Buffer          prev_buf = scan->xs_cbuf;
 506
 507                 scan->xs_cbuf = ReleaseAndReadBuffer(scan->xs_cbuf,
 508                                                                                          scan->heapRelation,
 509                                                                                          ItemPointerGetBlockNumber(tid));
 510
 511                 /*
 512                  * Prune page, but only if we weren't already on this page
 513                  */
 514                 if (prev_buf != scan->xs_cbuf)
 515                         heap_page_prune_opt(scan->heapRelation, scan->xs_cbuf,
 516                                                                 RecentGlobalXmin);
 517         }
 518
 519         /* Obtain share-lock on the buffer so we can examine visibility */
 520         LockBuffer(scan->xs_cbuf, BUFFER_LOCK_SHARE);
 521         got_heap_tuple = heap_hot_search_buffer(tid, scan->heapRelation,
 522                                                                                         scan->xs_cbuf,
 523                                                                                         scan->xs_snapshot,
 524                                                                                         &scan->xs_ctup,
 525                                                                                         &all_dead,
 526                                                                                         !scan->xs_continue_hot);
 527         LockBuffer(scan->xs_cbuf, BUFFER_LOCK_UNLOCK);
 528
 529         if (got_heap_tuple)
 530         {
 531                 /*
 532                  * Only in a non-MVCC snapshot can more than one member of the
 533                  * HOT chain be visible.
 534                  */
 535                 scan->xs_continue_hot = !IsMVCCSnapshot(scan->xs_snapshot);
 536                 pgstat_count_heap_fetch(scan->indexRelation);
 537                 return &scan->xs_ctup;
 538         }
 539
 540         /* We've reached the end of the HOT chain. */
 541         scan->xs_continue_hot = false;
 542
 543         /*
 544          * If we scanned a whole HOT chain and found only dead tuples, tell index
 545          * AM to kill its entry for that TID (this will take effect in the next
 546          * amgettuple call, in index_getnext_tid).  We do not do this when in
 547          * recovery because it may violate MVCC to do so.  See comments in
 548          * RelationGetIndexScan().
 549          */
 550         if (!scan->xactStartedInRecovery)
 551                 scan->kill_prior_tuple = all_dead;
 552
 553         return NULL;
 554 }
 555
 556 /* ----------------
 557  *              index_getnext - get the next heap tuple from a scan
 558  *
 559  * The result is the next heap tuple satisfying the scan keys and the
 560  * snapshot, or NULL if no more matching tuples 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 HeapTuple
 572 index_getnext(IndexScanDesc scan, ScanDirection direction)
 573 {
 574         HeapTuple       heapTuple;
 575         ItemPointer tid;
 576
 577         for (;;)
 578         {
 579                 if (scan->xs_continue_hot)
 580                 {
 581                         /*
 582                          * We are resuming scan of a HOT chain after having returned an
 583                          * earlier member.      Must still hold pin on current heap page.
 584                          */
 585                         Assert(BufferIsValid(scan->xs_cbuf));
 586                         Assert(ItemPointerGetBlockNumber(&scan->xs_ctup.t_self) ==
 587                                    BufferGetBlockNumber(scan->xs_cbuf));
 588                 }
 589                 else
 590                 {
 591                         /* Time to fetch the next TID from the index */
 592                         tid = index_getnext_tid(scan, direction);
 593
 594                         /* If we're out of index entries, we're done */
 595                         if (tid == NULL)
 596                                 break;
 597                 }
 598
 599                 /*
 600                  * Fetch the next (or only) visible heap tuple for this index entry.
 601                  * If we don't find anything, loop around and grab the next TID from
 602                  * the index.
 603                  */
 604                 heapTuple = index_fetch_heap(scan);
 605                 if (heapTuple != NULL)
 606                         return heapTuple;
 607         }
 608
 609         return NULL;                            /* failure exit */
 610 }
 611
 612 /* ----------------
 613  *              index_getbitmap - get all tuples at once from an index scan
 614  *
 615  * Adds the TIDs of all heap tuples satisfying the scan keys to a bitmap.
 616  * Since there's no interlock between the index scan and the eventual heap
 617  * access, this is only safe to use with MVCC-based snapshots: the heap
 618  * item slot could have been replaced by a newer tuple by the time we get
 619  * to it.
 620  *
 621  * Returns the number of matching tuples found.  (Note: this might be only
 622  * approximate, so it should only be used for statistical purposes.)
 623  * ----------------
 624  */
 625 int64
 626 index_getbitmap(IndexScanDesc scan, TIDBitmap *bitmap)
 627 {
 628         FmgrInfo   *procedure;
 629         int64           ntids;
 630         Datum           d;
 631
 632         SCAN_CHECKS;
 633         GET_SCAN_PROCEDURE(amgetbitmap);
 634
 635         /* just make sure this is false... */
 636         scan->kill_prior_tuple = false;
 637
 638         /*
 639          * have the am's getbitmap proc do all the work.
 640          */
 641         d = FunctionCall2(procedure,
 642                                           PointerGetDatum(scan),
 643                                           PointerGetDatum(bitmap));
 644
 645         ntids = DatumGetInt64(d);
 646
 647         /* If int8 is pass-by-ref, must free the result to avoid memory leak */
 648 #ifndef USE_FLOAT8_BYVAL
 649         pfree(DatumGetPointer(d));
 650 #endif
 651
 652         pgstat_count_index_tuples(scan->indexRelation, ntids);
 653
 654         return ntids;
 655 }
 656
 657 /* ----------------
 658  *              index_bulk_delete - do mass deletion of index entries
 659  *
 660  *              callback routine tells whether a given main-heap tuple is
 661  *              to be deleted
 662  *
 663  *              return value is an optional palloc'd struct of statistics
 664  * ----------------
 665  */
 666 IndexBulkDeleteResult *
 667 index_bulk_delete(IndexVacuumInfo *info,
 668                                   IndexBulkDeleteResult *stats,
 669                                   IndexBulkDeleteCallback callback,
 670                                   void *callback_state)
 671 {
 672         Relation        indexRelation = info->index;
 673         FmgrInfo   *procedure;
 674         IndexBulkDeleteResult *result;
 675
 676         RELATION_CHECKS;
 677         GET_REL_PROCEDURE(ambulkdelete);
 678
 679         result = (IndexBulkDeleteResult *)
 680                 DatumGetPointer(FunctionCall4(procedure,
 681                                                                           PointerGetDatum(info),
 682                                                                           PointerGetDatum(stats),
 683                                                                           PointerGetDatum((Pointer) callback),
 684                                                                           PointerGetDatum(callback_state)));
 685
 686         return result;
 687 }
 688
 689 /* ----------------
 690  *              index_vacuum_cleanup - do post-deletion cleanup of an index
 691  *
 692  *              return value is an optional palloc'd struct of statistics
 693  * ----------------
 694  */
 695 IndexBulkDeleteResult *
 696 index_vacuum_cleanup(IndexVacuumInfo *info,
 697                                          IndexBulkDeleteResult *stats)
 698 {
 699         Relation        indexRelation = info->index;
 700         FmgrInfo   *procedure;
 701         IndexBulkDeleteResult *result;
 702
 703         RELATION_CHECKS;
 704         GET_REL_PROCEDURE(amvacuumcleanup);
 705
 706         result = (IndexBulkDeleteResult *)
 707                 DatumGetPointer(FunctionCall2(procedure,
 708                                                                           PointerGetDatum(info),
 709                                                                           PointerGetDatum(stats)));
 710
 711         return result;
 712 }
 713
 714 /* ----------------
 715  *              index_getprocid
 716  *
 717  *              Index access methods typically require support routines that are
 718  *              not directly the implementation of any WHERE-clause query operator
 719  *              and so cannot be kept in pg_amop.  Instead, such routines are kept
 720  *              in pg_amproc.  These registered procedure OIDs are assigned numbers
 721  *              according to a convention established by the access method.
 722  *              The general index code doesn't know anything about the routines
 723  *              involved; it just builds an ordered list of them for
 724  *              each attribute on which an index is defined.
 725  *
 726  *              As of Postgres 8.3, support routines within an operator family
 727  *              are further subdivided by the "left type" and "right type" of the
 728  *              query operator(s) that they support.  The "default" functions for a
 729  *              particular indexed attribute are those with both types equal to
 730  *              the index opclass' opcintype (note that this is subtly different
 731  *              from the indexed attribute's own type: it may be a binary-compatible
 732  *              type instead).  Only the default functions are stored in relcache
 733  *              entries --- access methods can use the syscache to look up non-default
 734  *              functions.
 735  *
 736  *              This routine returns the requested default procedure OID for a
 737  *              particular indexed attribute.
 738  * ----------------
 739  */
 740 RegProcedure
 741 index_getprocid(Relation irel,
 742                                 AttrNumber attnum,
 743                                 uint16 procnum)
 744 {
 745         RegProcedure *loc;
 746         int                     nproc;
 747         int                     procindex;
 748
 749         nproc = irel->rd_am->amsupport;
 750
 751         Assert(procnum > 0 && procnum <= (uint16) nproc);
 752
 753         procindex = (nproc * (attnum - 1)) + (procnum - 1);
 754
 755         loc = irel->rd_support;
 756
 757         Assert(loc != NULL);
 758
 759         return loc[procindex];
 760 }
 761
 762 /* ----------------
 763  *              index_getprocinfo
 764  *
 765  *              This routine allows index AMs to keep fmgr lookup info for
 766  *              support procs in the relcache.  As above, only the "default"
 767  *              functions for any particular indexed attribute are cached.
 768  *
 769  * Note: the return value points into cached data that will be lost during
 770  * any relcache rebuild!  Therefore, either use the callinfo right away,
 771  * or save it only after having acquired some type of lock on the index rel.
 772  * ----------------
 773  */
 774 FmgrInfo *
 775 index_getprocinfo(Relation irel,
 776                                   AttrNumber attnum,
 777                                   uint16 procnum)
 778 {
 779         FmgrInfo   *locinfo;
 780         int                     nproc;
 781         int                     procindex;
 782
 783         nproc = irel->rd_am->amsupport;
 784
 785         Assert(procnum > 0 && procnum <= (uint16) nproc);
 786
 787         procindex = (nproc * (attnum - 1)) + (procnum - 1);
 788
 789         locinfo = irel->rd_supportinfo;
 790
 791         Assert(locinfo != NULL);
 792
 793         locinfo += procindex;
 794
 795         /* Initialize the lookup info if first time through */
 796         if (locinfo->fn_oid == InvalidOid)
 797         {
 798                 RegProcedure *loc = irel->rd_support;
 799                 RegProcedure procId;
 800
 801                 Assert(loc != NULL);
 802
 803                 procId = loc[procindex];
 804
 805                 /*
 806                  * Complain if function was not found during IndexSupportInitialize.
 807                  * This should not happen unless the system tables contain bogus
 808                  * entries for the index opclass.  (If an AM wants to allow a support
 809                  * function to be optional, it can use index_getprocid.)
 810                  */
 811                 if (!RegProcedureIsValid(procId))
 812                         elog(ERROR, "missing support function %d for attribute %d of index \"%s\"",
 813                                  procnum, attnum, RelationGetRelationName(irel));
 814
 815                 fmgr_info_cxt(procId, locinfo, irel->rd_indexcxt);
 816         }
 817
 818         return locinfo;
 819 }