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) 1996-2008, PostgreSQL Global Development Group
   7  * Portions Copyright (c) 1994, Regents of the University of California
   8  *
   9  *
  10  * IDENTIFICATION
  11  *        $PostgreSQL: pgsql/src/backend/access/index/indexam.c,v 1.103 2008/03/26 18:48:59 alvherre Exp $
  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_multi - start a scan of an index with amgetmulti
  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   - get the next tuple from a scan
  24  *              index_getmulti  - get multiple tuples from a scan
  25  *              index_bulk_delete       - bulk deletion of index tuples
  26  *              index_vacuum_cleanup    - post-deletion cleanup of an index
  27  *              index_getprocid - get a support procedure OID
  28  *              index_getprocinfo - get a support procedure's lookup info
  29  *
  30  * NOTES
  31  *              This file contains the index_ routines which used
  32  *              to be a scattered collection of stuff in access/genam.
  33  *
  34  *
  35  * old comments
  36  *              Scans are implemented as follows:
  37  *
  38  *              `0' represents an invalid item pointer.
  39  *              `-' represents an unknown item pointer.
  40  *              `X' represents a known item pointers.
  41  *              `+' represents known or invalid item pointers.
  42  *              `*' represents any item pointers.
  43  *
  44  *              State is represented by a triple of these symbols in the order of
  45  *              previous, current, next.  Note that the case of reverse scans works
  46  *              identically.
  47  *
  48  *                              State   Result
  49  *              (1)             + + -   + 0 0                   (if the next item pointer is invalid)
  50  *              (2)                             + X -                   (otherwise)
  51  *              (3)             * 0 0   * 0 0                   (no change)
  52  *              (4)             + X 0   X 0 0                   (shift)
  53  *              (5)             * + X   + X -                   (shift, add unknown)
  54  *
  55  *              All other states cannot occur.
  56  *
  57  *              Note: It would be possible to cache the status of the previous and
  58  *                        next item pointer using the flags.
  59  *
  60  *-------------------------------------------------------------------------
  61  */
  62
  63 #include "postgres.h"
  64
  65 #include "access/genam.h"
  66 #include "access/heapam.h"
  67 #include "access/transam.h"
  68 #include "pgstat.h"
  69 #include "utils/relcache.h"
  70 #include "utils/snapmgr.h"
  71
  72
  73 /* ----------------------------------------------------------------
  74  *                                      macros used in index_ routines
  75  * ----------------------------------------------------------------
  76  */
  77 #define RELATION_CHECKS \
  78 ( \
  79         AssertMacro(RelationIsValid(indexRelation)), \
  80         AssertMacro(PointerIsValid(indexRelation->rd_am)) \
  81 )
  82
  83 #define SCAN_CHECKS \
  84 ( \
  85         AssertMacro(IndexScanIsValid(scan)), \
  86         AssertMacro(RelationIsValid(scan->indexRelation)), \
  87         AssertMacro(PointerIsValid(scan->indexRelation->rd_am)) \
  88 )
  89
  90 #define GET_REL_PROCEDURE(pname) \
  91 do { \
  92         procedure = &indexRelation->rd_aminfo->pname; \
  93         if (!OidIsValid(procedure->fn_oid)) \
  94         { \
  95                 RegProcedure    procOid = indexRelation->rd_am->pname; \
  96                 if (!RegProcedureIsValid(procOid)) \
  97                         elog(ERROR, "invalid %s regproc", CppAsString(pname)); \
  98                 fmgr_info_cxt(procOid, procedure, indexRelation->rd_indexcxt); \
  99         } \
 100 } while(0)
 101
 102 #define GET_SCAN_PROCEDURE(pname) \
 103 do { \
 104         procedure = &scan->indexRelation->rd_aminfo->pname; \
 105         if (!OidIsValid(procedure->fn_oid)) \
 106         { \
 107                 RegProcedure    procOid = scan->indexRelation->rd_am->pname; \
 108                 if (!RegProcedureIsValid(procOid)) \
 109                         elog(ERROR, "invalid %s regproc", CppAsString(pname)); \
 110                 fmgr_info_cxt(procOid, procedure, scan->indexRelation->rd_indexcxt); \
 111         } \
 112 } while(0)
 113
 114 static IndexScanDesc index_beginscan_internal(Relation indexRelation,
 115                                                  int nkeys, ScanKey key);
 116
 117
 118 /* ----------------------------------------------------------------
 119  *                                 index_ interface functions
 120  * ----------------------------------------------------------------
 121  */
 122
 123 /* ----------------
 124  *              index_open - open an index relation by relation OID
 125  *
 126  *              If lockmode is not "NoLock", the specified kind of lock is
 127  *              obtained on the index.  (Generally, NoLock should only be
 128  *              used if the caller knows it has some appropriate lock on the
 129  *              index already.)
 130  *
 131  *              An error is raised if the index does not exist.
 132  *
 133  *              This is a convenience routine adapted for indexscan use.
 134  *              Some callers may prefer to use relation_open directly.
 135  * ----------------
 136  */
 137 Relation
 138 index_open(Oid relationId, LOCKMODE lockmode)
 139 {
 140         Relation        r;
 141
 142         r = relation_open(relationId, lockmode);
 143
 144         if (r->rd_rel->relkind != RELKIND_INDEX)
 145                 ereport(ERROR,
 146                                 (errcode(ERRCODE_WRONG_OBJECT_TYPE),
 147                                  errmsg("\"%s\" is not an index",
 148                                                 RelationGetRelationName(r))));
 149
 150         return r;
 151 }
 152
 153 /* ----------------
 154  *              index_close - close an index relation
 155  *
 156  *              If lockmode is not "NoLock", we then release the specified lock.
 157  *
 158  *              Note that it is often sensible to hold a lock beyond index_close;
 159  *              in that case, the lock is released automatically at xact end.
 160  * ----------------
 161  */
 162 void
 163 index_close(Relation relation, LOCKMODE lockmode)
 164 {
 165         LockRelId       relid = relation->rd_lockInfo.lockRelId;
 166
 167         Assert(lockmode >= NoLock && lockmode < MAX_LOCKMODES);
 168
 169         /* The relcache does the real work... */
 170         RelationClose(relation);
 171
 172         if (lockmode != NoLock)
 173                 UnlockRelationId(&relid, lockmode);
 174 }
 175
 176 /* ----------------
 177  *              index_insert - insert an index tuple into a relation
 178  * ----------------
 179  */
 180 bool
 181 index_insert(Relation indexRelation,
 182                          Datum *values,
 183                          bool *isnull,
 184                          ItemPointer heap_t_ctid,
 185                          Relation heapRelation,
 186                          bool check_uniqueness)
 187 {
 188         FmgrInfo   *procedure;
 189
 190         RELATION_CHECKS;
 191         GET_REL_PROCEDURE(aminsert);
 192
 193         /*
 194          * have the am's insert proc do all the work.
 195          */
 196         return DatumGetBool(FunctionCall6(procedure,
 197                                                                           PointerGetDatum(indexRelation),
 198                                                                           PointerGetDatum(values),
 199                                                                           PointerGetDatum(isnull),
 200                                                                           PointerGetDatum(heap_t_ctid),
 201                                                                           PointerGetDatum(heapRelation),
 202                                                                           BoolGetDatum(check_uniqueness)));
 203 }
 204
 205 /*
 206  * index_beginscan - start a scan of an index with amgettuple
 207  *
 208  * Note: heapRelation may be NULL if there is no intention of calling
 209  * index_getnext on this scan; index_getnext_indexitem will not use the
 210  * heapRelation link (nor the snapshot).  However, the caller had better
 211  * be holding some kind of lock on the heap relation in any case, to ensure
 212  * no one deletes it (or the index) out from under us.  Caller must also
 213  * be holding a lock on the index.
 214  */
 215 IndexScanDesc
 216 index_beginscan(Relation heapRelation,
 217                                 Relation indexRelation,
 218                                 Snapshot snapshot,
 219                                 int nkeys, ScanKey key)
 220 {
 221         IndexScanDesc scan;
 222
 223         scan = index_beginscan_internal(indexRelation, nkeys, key);
 224
 225         /*
 226          * Save additional parameters into the scandesc.  Everything else was set
 227          * up by RelationGetIndexScan.
 228          */
 229         scan->is_multiscan = false;
 230         scan->heapRelation = heapRelation;
 231         scan->xs_snapshot = snapshot;
 232
 233         return scan;
 234 }
 235
 236 /*
 237  * index_beginscan_multi - start a scan of an index with amgetmulti
 238  *
 239  * As above, caller had better be holding some lock on the parent heap
 240  * relation, even though it's not explicitly mentioned here.
 241  */
 242 IndexScanDesc
 243 index_beginscan_multi(Relation indexRelation,
 244                                           Snapshot snapshot,
 245                                           int nkeys, ScanKey key)
 246 {
 247         IndexScanDesc scan;
 248
 249         scan = index_beginscan_internal(indexRelation, nkeys, key);
 250
 251         /*
 252          * Save additional parameters into the scandesc.  Everything else was set
 253          * up by RelationGetIndexScan.
 254          */
 255         scan->is_multiscan = true;
 256         scan->xs_snapshot = snapshot;
 257
 258         return scan;
 259 }
 260
 261 /*
 262  * index_beginscan_internal --- common code for index_beginscan variants
 263  */
 264 static IndexScanDesc
 265 index_beginscan_internal(Relation indexRelation,
 266                                                  int nkeys, ScanKey key)
 267 {
 268         IndexScanDesc scan;
 269         FmgrInfo   *procedure;
 270
 271         RELATION_CHECKS;
 272         GET_REL_PROCEDURE(ambeginscan);
 273
 274         /*
 275          * We hold a reference count to the relcache entry throughout the scan.
 276          */
 277         RelationIncrementReferenceCount(indexRelation);
 278
 279         /*
 280          * Tell the AM to open a scan.
 281          */
 282         scan = (IndexScanDesc)
 283                 DatumGetPointer(FunctionCall3(procedure,
 284                                                                           PointerGetDatum(indexRelation),
 285                                                                           Int32GetDatum(nkeys),
 286                                                                           PointerGetDatum(key)));
 287
 288         return scan;
 289 }
 290
 291 /* ----------------
 292  *              index_rescan  - (re)start a scan of an index
 293  *
 294  * The caller may specify a new set of scankeys (but the number of keys
 295  * cannot change).      To restart the scan without changing keys, pass NULL
 296  * for the key array.
 297  *
 298  * Note that this is also called when first starting an indexscan;
 299  * see RelationGetIndexScan.  Keys *must* be passed in that case,
 300  * unless scan->numberOfKeys is zero.
 301  * ----------------
 302  */
 303 void
 304 index_rescan(IndexScanDesc scan, ScanKey key)
 305 {
 306         FmgrInfo   *procedure;
 307
 308         SCAN_CHECKS;
 309         GET_SCAN_PROCEDURE(amrescan);
 310
 311         /* Release any held pin on a heap page */
 312         if (BufferIsValid(scan->xs_cbuf))
 313         {
 314                 ReleaseBuffer(scan->xs_cbuf);
 315                 scan->xs_cbuf = InvalidBuffer;
 316         }
 317
 318         scan->xs_next_hot = InvalidOffsetNumber;
 319
 320         scan->kill_prior_tuple = false;         /* for safety */
 321
 322         FunctionCall2(procedure,
 323                                   PointerGetDatum(scan),
 324                                   PointerGetDatum(key));
 325 }
 326
 327 /* ----------------
 328  *              index_endscan - end a scan
 329  * ----------------
 330  */
 331 void
 332 index_endscan(IndexScanDesc scan)
 333 {
 334         FmgrInfo   *procedure;
 335
 336         SCAN_CHECKS;
 337         GET_SCAN_PROCEDURE(amendscan);
 338
 339         /* Release any held pin on a heap page */
 340         if (BufferIsValid(scan->xs_cbuf))
 341         {
 342                 ReleaseBuffer(scan->xs_cbuf);
 343                 scan->xs_cbuf = InvalidBuffer;
 344         }
 345
 346         /* End the AM's scan */
 347         FunctionCall1(procedure, PointerGetDatum(scan));
 348
 349         /* Release index refcount acquired by index_beginscan */
 350         RelationDecrementReferenceCount(scan->indexRelation);
 351
 352         /* Release the scan data structure itself */
 353         IndexScanEnd(scan);
 354 }
 355
 356 /* ----------------
 357  *              index_markpos  - mark a scan position
 358  * ----------------
 359  */
 360 void
 361 index_markpos(IndexScanDesc scan)
 362 {
 363         FmgrInfo   *procedure;
 364
 365         SCAN_CHECKS;
 366         GET_SCAN_PROCEDURE(ammarkpos);
 367
 368         FunctionCall1(procedure, PointerGetDatum(scan));
 369 }
 370
 371 /* ----------------
 372  *              index_restrpos  - restore a scan position
 373  *
 374  * NOTE: this only restores the internal scan state of the index AM.
 375  * The current result tuple (scan->xs_ctup) doesn't change.  See comments
 376  * for ExecRestrPos().
 377  *
 378  * NOTE: in the presence of HOT chains, mark/restore only works correctly
 379  * if the scan's snapshot is MVCC-safe; that ensures that there's at most one
 380  * returnable tuple in each HOT chain, and so restoring the prior state at the
 381  * granularity of the index AM is sufficient.  Since the only current user
 382  * of mark/restore functionality is nodeMergejoin.c, this effectively means
 383  * that merge-join plans only work for MVCC snapshots.  This could be fixed
 384  * if necessary, but for now it seems unimportant.
 385  * ----------------
 386  */
 387 void
 388 index_restrpos(IndexScanDesc scan)
 389 {
 390         FmgrInfo   *procedure;
 391
 392         Assert(IsMVCCSnapshot(scan->xs_snapshot));
 393
 394         SCAN_CHECKS;
 395         GET_SCAN_PROCEDURE(amrestrpos);
 396
 397         scan->xs_next_hot = InvalidOffsetNumber;
 398
 399         scan->kill_prior_tuple = false;         /* for safety */
 400
 401         FunctionCall1(procedure, PointerGetDatum(scan));
 402 }
 403
 404 /* ----------------
 405  *              index_getnext - get the next heap tuple from a scan
 406  *
 407  * The result is the next heap tuple satisfying the scan keys and the
 408  * snapshot, or NULL if no more matching tuples exist.  On success,
 409  * the buffer containing the heap tuple is pinned (the pin will be dropped
 410  * at the next index_getnext or index_endscan).
 411  * ----------------
 412  */
 413 HeapTuple
 414 index_getnext(IndexScanDesc scan, ScanDirection direction)
 415 {
 416         HeapTuple       heapTuple = &scan->xs_ctup;
 417         ItemPointer tid = &heapTuple->t_self;
 418         FmgrInfo   *procedure;
 419
 420         SCAN_CHECKS;
 421         GET_SCAN_PROCEDURE(amgettuple);
 422
 423         /*
 424          * We always reset xs_hot_dead; if we are here then either we are just
 425          * starting the scan, or we previously returned a visible tuple, and in
 426          * either case it's inappropriate to kill the prior index entry.
 427          */
 428         scan->xs_hot_dead = false;
 429
 430         for (;;)
 431         {
 432                 OffsetNumber offnum;
 433                 bool            at_chain_start;
 434                 Page            dp;
 435
 436                 if (scan->xs_next_hot != InvalidOffsetNumber)
 437                 {
 438                         /*
 439                          * We are resuming scan of a HOT chain after having returned an
 440                          * earlier member.      Must still hold pin on current heap page.
 441                          */
 442                         Assert(BufferIsValid(scan->xs_cbuf));
 443                         Assert(ItemPointerGetBlockNumber(tid) ==
 444                                    BufferGetBlockNumber(scan->xs_cbuf));
 445                         Assert(TransactionIdIsValid(scan->xs_prev_xmax));
 446                         offnum = scan->xs_next_hot;
 447                         at_chain_start = false;
 448                         scan->xs_next_hot = InvalidOffsetNumber;
 449                 }
 450                 else
 451                 {
 452                         bool            found;
 453                         Buffer          prev_buf;
 454
 455                         /*
 456                          * If we scanned a whole HOT chain and found only dead tuples,
 457                          * tell index AM to kill its entry for that TID.
 458                          */
 459                         scan->kill_prior_tuple = scan->xs_hot_dead;
 460
 461                         /*
 462                          * The AM's gettuple proc finds the next index entry matching the
 463                          * scan keys, and puts the TID in xs_ctup.t_self (ie, *tid).
 464                          */
 465                         found = DatumGetBool(FunctionCall2(procedure,
 466                                                                                            PointerGetDatum(scan),
 467                                                                                            Int32GetDatum(direction)));
 468
 469                         /* Reset kill flag immediately for safety */
 470                         scan->kill_prior_tuple = false;
 471
 472                         /* If we're out of index entries, break out of outer loop */
 473                         if (!found)
 474                                 break;
 475
 476                         pgstat_count_index_tuples(scan->indexRelation, 1);
 477
 478                         /* Switch to correct buffer if we don't have it already */
 479                         prev_buf = scan->xs_cbuf;
 480                         scan->xs_cbuf = ReleaseAndReadBuffer(scan->xs_cbuf,
 481                                                                                                  scan->heapRelation,
 482                                                                                          ItemPointerGetBlockNumber(tid));
 483
 484                         /*
 485                          * Prune page, but only if we weren't already on this page
 486                          */
 487                         if (prev_buf != scan->xs_cbuf)
 488                                 heap_page_prune_opt(scan->heapRelation, scan->xs_cbuf,
 489                                                                         RecentGlobalXmin);
 490
 491                         /* Prepare to scan HOT chain starting at index-referenced offnum */
 492                         offnum = ItemPointerGetOffsetNumber(tid);
 493                         at_chain_start = true;
 494
 495                         /* We don't know what the first tuple's xmin should be */
 496                         scan->xs_prev_xmax = InvalidTransactionId;
 497
 498                         /* Initialize flag to detect if all entries are dead */
 499                         scan->xs_hot_dead = true;
 500                 }
 501
 502                 /* Obtain share-lock on the buffer so we can examine visibility */
 503                 LockBuffer(scan->xs_cbuf, BUFFER_LOCK_SHARE);
 504
 505                 dp = (Page) BufferGetPage(scan->xs_cbuf);
 506
 507                 /* Scan through possible multiple members of HOT-chain */
 508                 for (;;)
 509                 {
 510                         ItemId          lp;
 511                         ItemPointer ctid;
 512
 513                         /* check for bogus TID */
 514                         if (offnum < FirstOffsetNumber ||
 515                                 offnum > PageGetMaxOffsetNumber(dp))
 516                                 break;
 517
 518                         lp = PageGetItemId(dp, offnum);
 519
 520                         /* check for unused, dead, or redirected items */
 521                         if (!ItemIdIsNormal(lp))
 522                         {
 523                                 /* We should only see a redirect at start of chain */
 524                                 if (ItemIdIsRedirected(lp) && at_chain_start)
 525                                 {
 526                                         /* Follow the redirect */
 527                                         offnum = ItemIdGetRedirect(lp);
 528                                         at_chain_start = false;
 529                                         continue;
 530                                 }
 531                                 /* else must be end of chain */
 532                                 break;
 533                         }
 534
 535                         /*
 536                          * We must initialize all of *heapTuple (ie, scan->xs_ctup) since
 537                          * it is returned to the executor on success.
 538                          */
 539                         heapTuple->t_data = (HeapTupleHeader) PageGetItem(dp, lp);
 540                         heapTuple->t_len = ItemIdGetLength(lp);
 541                         ItemPointerSetOffsetNumber(tid, offnum);
 542                         heapTuple->t_tableOid = RelationGetRelid(scan->heapRelation);
 543                         ctid = &heapTuple->t_data->t_ctid;
 544
 545                         /*
 546                          * Shouldn't see a HEAP_ONLY tuple at chain start.  (This test
 547                          * should be unnecessary, since the chain root can't be removed
 548                          * while we have pin on the index entry, but let's make it
 549                          * anyway.)
 550                          */
 551                         if (at_chain_start && HeapTupleIsHeapOnly(heapTuple))
 552                                 break;
 553
 554                         /*
 555                          * The xmin should match the previous xmax value, else chain is
 556                          * broken.      (Note: this test is not optional because it protects
 557                          * us against the case where the prior chain member's xmax aborted
 558                          * since we looked at it.)
 559                          */
 560                         if (TransactionIdIsValid(scan->xs_prev_xmax) &&
 561                                 !TransactionIdEquals(scan->xs_prev_xmax,
 562                                                                   HeapTupleHeaderGetXmin(heapTuple->t_data)))
 563                                 break;
 564
 565                         /* If it's visible per the snapshot, we must return it */
 566                         if (HeapTupleSatisfiesVisibility(heapTuple, scan->xs_snapshot,
 567                                                                                          scan->xs_cbuf))
 568                         {
 569                                 /*
 570                                  * If the snapshot is MVCC, we know that it could accept at
 571                                  * most one member of the HOT chain, so we can skip examining
 572                                  * any more members.  Otherwise, check for continuation of the
 573                                  * HOT-chain, and set state for next time.
 574                                  */
 575                                 if (IsMVCCSnapshot(scan->xs_snapshot))
 576                                         scan->xs_next_hot = InvalidOffsetNumber;
 577                                 else if (HeapTupleIsHotUpdated(heapTuple))
 578                                 {
 579                                         Assert(ItemPointerGetBlockNumber(ctid) ==
 580                                                    ItemPointerGetBlockNumber(tid));
 581                                         scan->xs_next_hot = ItemPointerGetOffsetNumber(ctid);
 582                                         scan->xs_prev_xmax = HeapTupleHeaderGetXmax(heapTuple->t_data);
 583                                 }
 584                                 else
 585                                         scan->xs_next_hot = InvalidOffsetNumber;
 586
 587                                 LockBuffer(scan->xs_cbuf, BUFFER_LOCK_UNLOCK);
 588
 589                                 pgstat_count_heap_fetch(scan->indexRelation);
 590
 591                                 return heapTuple;
 592                         }
 593
 594                         /*
 595                          * If we can't see it, maybe no one else can either.  Check to see
 596                          * if the tuple is dead to all transactions.  If we find that all
 597                          * the tuples in the HOT chain are dead, we'll signal the index AM
 598                          * to not return that TID on future indexscans.
 599                          */
 600                         if (scan->xs_hot_dead &&
 601                                 HeapTupleSatisfiesVacuum(heapTuple->t_data, RecentGlobalXmin,
 602                                                                                  scan->xs_cbuf) != HEAPTUPLE_DEAD)
 603                                 scan->xs_hot_dead = false;
 604
 605                         /*
 606                          * Check to see if HOT chain continues past this tuple; if so
 607                          * fetch the next offnum (we don't bother storing it into
 608                          * xs_next_hot, but must store xs_prev_xmax), and loop around.
 609                          */
 610                         if (HeapTupleIsHotUpdated(heapTuple))
 611                         {
 612                                 Assert(ItemPointerGetBlockNumber(ctid) ==
 613                                            ItemPointerGetBlockNumber(tid));
 614                                 offnum = ItemPointerGetOffsetNumber(ctid);
 615                                 at_chain_start = false;
 616                                 scan->xs_prev_xmax = HeapTupleHeaderGetXmax(heapTuple->t_data);
 617                         }
 618                         else
 619                                 break;                  /* end of chain */
 620                 }                                               /* loop over a single HOT chain */
 621
 622                 LockBuffer(scan->xs_cbuf, BUFFER_LOCK_UNLOCK);
 623
 624                 /* Loop around to ask index AM for another TID */
 625                 scan->xs_next_hot = InvalidOffsetNumber;
 626         }
 627
 628         /* Release any held pin on a heap page */
 629         if (BufferIsValid(scan->xs_cbuf))
 630         {
 631                 ReleaseBuffer(scan->xs_cbuf);
 632                 scan->xs_cbuf = InvalidBuffer;
 633         }
 634
 635         return NULL;                            /* failure exit */
 636 }
 637
 638 /* ----------------
 639  *              index_getnext_indexitem - get the next index tuple from a scan
 640  *
 641  * Finds the next index tuple satisfying the scan keys.  Note that the
 642  * corresponding heap tuple is not accessed, and thus no time qual (snapshot)
 643  * check is done, other than the index AM's internal check for killed tuples
 644  * (which most callers of this routine will probably want to suppress by
 645  * setting scan->ignore_killed_tuples = false).
 646  *
 647  * On success (TRUE return), the heap TID of the found index entry is in
 648  * scan->xs_ctup.t_self.  scan->xs_cbuf is untouched.
 649  * ----------------
 650  */
 651 bool
 652 index_getnext_indexitem(IndexScanDesc scan,
 653                                                 ScanDirection direction)
 654 {
 655         FmgrInfo   *procedure;
 656         bool            found;
 657
 658         SCAN_CHECKS;
 659         GET_SCAN_PROCEDURE(amgettuple);
 660
 661         /* just make sure this is false... */
 662         scan->kill_prior_tuple = false;
 663
 664         /*
 665          * have the am's gettuple proc do all the work.
 666          */
 667         found = DatumGetBool(FunctionCall2(procedure,
 668                                                                            PointerGetDatum(scan),
 669                                                                            Int32GetDatum(direction)));
 670
 671         if (found)
 672                 pgstat_count_index_tuples(scan->indexRelation, 1);
 673
 674         return found;
 675 }
 676
 677 /* ----------------
 678  *              index_getmulti - get multiple tuples from an index scan
 679  *
 680  * Collects the TIDs of multiple heap tuples satisfying the scan keys.
 681  * Since there's no interlock between the index scan and the eventual heap
 682  * access, this is only safe to use with MVCC-based snapshots: the heap
 683  * item slot could have been replaced by a newer tuple by the time we get
 684  * to it.
 685  *
 686  * A TRUE result indicates more calls should occur; a FALSE result says the
 687  * scan is done.  *returned_tids could be zero or nonzero in either case.
 688  * ----------------
 689  */
 690 bool
 691 index_getmulti(IndexScanDesc scan,
 692                            ItemPointer tids, int32 max_tids,
 693                            int32 *returned_tids)
 694 {
 695         FmgrInfo   *procedure;
 696         bool            found;
 697
 698         SCAN_CHECKS;
 699         GET_SCAN_PROCEDURE(amgetmulti);
 700
 701         /* just make sure this is false... */
 702         scan->kill_prior_tuple = false;
 703
 704         /*
 705          * have the am's getmulti proc do all the work.
 706          */
 707         found = DatumGetBool(FunctionCall4(procedure,
 708                                                                            PointerGetDatum(scan),
 709                                                                            PointerGetDatum(tids),
 710                                                                            Int32GetDatum(max_tids),
 711                                                                            PointerGetDatum(returned_tids)));
 712
 713         pgstat_count_index_tuples(scan->indexRelation, *returned_tids);
 714
 715         return found;
 716 }
 717
 718 /* ----------------
 719  *              index_bulk_delete - do mass deletion of index entries
 720  *
 721  *              callback routine tells whether a given main-heap tuple is
 722  *              to be deleted
 723  *
 724  *              return value is an optional palloc'd struct of statistics
 725  * ----------------
 726  */
 727 IndexBulkDeleteResult *
 728 index_bulk_delete(IndexVacuumInfo *info,
 729                                   IndexBulkDeleteResult *stats,
 730                                   IndexBulkDeleteCallback callback,
 731                                   void *callback_state)
 732 {
 733         Relation        indexRelation = info->index;
 734         FmgrInfo   *procedure;
 735         IndexBulkDeleteResult *result;
 736
 737         RELATION_CHECKS;
 738         GET_REL_PROCEDURE(ambulkdelete);
 739
 740         result = (IndexBulkDeleteResult *)
 741                 DatumGetPointer(FunctionCall4(procedure,
 742                                                                           PointerGetDatum(info),
 743                                                                           PointerGetDatum(stats),
 744                                                                           PointerGetDatum((Pointer) callback),
 745                                                                           PointerGetDatum(callback_state)));
 746
 747         return result;
 748 }
 749
 750 /* ----------------
 751  *              index_vacuum_cleanup - do post-deletion cleanup of an index
 752  *
 753  *              return value is an optional palloc'd struct of statistics
 754  * ----------------
 755  */
 756 IndexBulkDeleteResult *
 757 index_vacuum_cleanup(IndexVacuumInfo *info,
 758                                          IndexBulkDeleteResult *stats)
 759 {
 760         Relation        indexRelation = info->index;
 761         FmgrInfo   *procedure;
 762         IndexBulkDeleteResult *result;
 763
 764         RELATION_CHECKS;
 765         GET_REL_PROCEDURE(amvacuumcleanup);
 766
 767         result = (IndexBulkDeleteResult *)
 768                 DatumGetPointer(FunctionCall2(procedure,
 769                                                                           PointerGetDatum(info),
 770                                                                           PointerGetDatum(stats)));
 771
 772         return result;
 773 }
 774
 775 /* ----------------
 776  *              index_getprocid
 777  *
 778  *              Index access methods typically require support routines that are
 779  *              not directly the implementation of any WHERE-clause query operator
 780  *              and so cannot be kept in pg_amop.  Instead, such routines are kept
 781  *              in pg_amproc.  These registered procedure OIDs are assigned numbers
 782  *              according to a convention established by the access method.
 783  *              The general index code doesn't know anything about the routines
 784  *              involved; it just builds an ordered list of them for
 785  *              each attribute on which an index is defined.
 786  *
 787  *              As of Postgres 8.3, support routines within an operator family
 788  *              are further subdivided by the "left type" and "right type" of the
 789  *              query operator(s) that they support.  The "default" functions for a
 790  *              particular indexed attribute are those with both types equal to
 791  *              the index opclass' opcintype (note that this is subtly different
 792  *              from the indexed attribute's own type: it may be a binary-compatible
 793  *              type instead).  Only the default functions are stored in relcache
 794  *              entries --- access methods can use the syscache to look up non-default
 795  *              functions.
 796  *
 797  *              This routine returns the requested default procedure OID for a
 798  *              particular indexed attribute.
 799  * ----------------
 800  */
 801 RegProcedure
 802 index_getprocid(Relation irel,
 803                                 AttrNumber attnum,
 804                                 uint16 procnum)
 805 {
 806         RegProcedure *loc;
 807         int                     nproc;
 808         int                     procindex;
 809
 810         nproc = irel->rd_am->amsupport;
 811
 812         Assert(procnum > 0 && procnum <= (uint16) nproc);
 813
 814         procindex = (nproc * (attnum - 1)) + (procnum - 1);
 815
 816         loc = irel->rd_support;
 817
 818         Assert(loc != NULL);
 819
 820         return loc[procindex];
 821 }
 822
 823 /* ----------------
 824  *              index_getprocinfo
 825  *
 826  *              This routine allows index AMs to keep fmgr lookup info for
 827  *              support procs in the relcache.  As above, only the "default"
 828  *              functions for any particular indexed attribute are cached.
 829  *
 830  * Note: the return value points into cached data that will be lost during
 831  * any relcache rebuild!  Therefore, either use the callinfo right away,
 832  * or save it only after having acquired some type of lock on the index rel.
 833  * ----------------
 834  */
 835 FmgrInfo *
 836 index_getprocinfo(Relation irel,
 837                                   AttrNumber attnum,
 838                                   uint16 procnum)
 839 {
 840         FmgrInfo   *locinfo;
 841         int                     nproc;
 842         int                     procindex;
 843
 844         nproc = irel->rd_am->amsupport;
 845
 846         Assert(procnum > 0 && procnum <= (uint16) nproc);
 847
 848         procindex = (nproc * (attnum - 1)) + (procnum - 1);
 849
 850         locinfo = irel->rd_supportinfo;
 851
 852         Assert(locinfo != NULL);
 853
 854         locinfo += procindex;
 855
 856         /* Initialize the lookup info if first time through */
 857         if (locinfo->fn_oid == InvalidOid)
 858         {
 859                 RegProcedure *loc = irel->rd_support;
 860                 RegProcedure procId;
 861
 862                 Assert(loc != NULL);
 863
 864                 procId = loc[procindex];
 865
 866                 /*
 867                  * Complain if function was not found during IndexSupportInitialize.
 868                  * This should not happen unless the system tables contain bogus
 869                  * entries for the index opclass.  (If an AM wants to allow a support
 870                  * function to be optional, it can use index_getprocid.)
 871                  */
 872                 if (!RegProcedureIsValid(procId))
 873                         elog(ERROR, "missing support function %d for attribute %d of index \"%s\"",
 874                                  procnum, attnum, RelationGetRelationName(irel));
 875
 876                 fmgr_info_cxt(procId, locinfo, irel->rd_indexcxt);
 877         }
 878
 879         return locinfo;
 880 }