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 1.109 2008/06/19 00:46:03 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_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   - get the next tuple from a scan
  24  *              index_getbitmap - get all 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/relscan.h"
  66 #include "access/transam.h"
  67 #include "pgstat.h"
  68 #include "storage/bufmgr.h"
  69 #include "storage/lmgr.h"
  70 #include "utils/relcache.h"
  71 #include "utils/snapmgr.h"
  72 #include "utils/tqual.h"
  73
  74
  75 /* ----------------------------------------------------------------
  76  *                                      macros used in index_ routines
  77  * ----------------------------------------------------------------
  78  */
  79 #define RELATION_CHECKS \
  80 ( \
  81         AssertMacro(RelationIsValid(indexRelation)), \
  82         AssertMacro(PointerIsValid(indexRelation->rd_am)) \
  83 )
  84
  85 #define SCAN_CHECKS \
  86 ( \
  87         AssertMacro(IndexScanIsValid(scan)), \
  88         AssertMacro(RelationIsValid(scan->indexRelation)), \
  89         AssertMacro(PointerIsValid(scan->indexRelation->rd_am)) \
  90 )
  91
  92 #define GET_REL_PROCEDURE(pname) \
  93 do { \
  94         procedure = &indexRelation->rd_aminfo->pname; \
  95         if (!OidIsValid(procedure->fn_oid)) \
  96         { \
  97                 RegProcedure    procOid = indexRelation->rd_am->pname; \
  98                 if (!RegProcedureIsValid(procOid)) \
  99                         elog(ERROR, "invalid %s regproc", CppAsString(pname)); \
 100                 fmgr_info_cxt(procOid, procedure, indexRelation->rd_indexcxt); \
 101         } \
 102 } while(0)
 103
 104 #define GET_SCAN_PROCEDURE(pname) \
 105 do { \
 106         procedure = &scan->indexRelation->rd_aminfo->pname; \
 107         if (!OidIsValid(procedure->fn_oid)) \
 108         { \
 109                 RegProcedure    procOid = scan->indexRelation->rd_am->pname; \
 110                 if (!RegProcedureIsValid(procOid)) \
 111                         elog(ERROR, "invalid %s regproc", CppAsString(pname)); \
 112                 fmgr_info_cxt(procOid, procedure, scan->indexRelation->rd_indexcxt); \
 113         } \
 114 } while(0)
 115
 116 static IndexScanDesc index_beginscan_internal(Relation indexRelation,
 117                                                  int nkeys, ScanKey key);
 118
 119
 120 /* ----------------------------------------------------------------
 121  *                                 index_ interface functions
 122  * ----------------------------------------------------------------
 123  */
 124
 125 /* ----------------
 126  *              index_open - open an index relation by relation OID
 127  *
 128  *              If lockmode is not "NoLock", the specified kind of lock is
 129  *              obtained on the index.  (Generally, NoLock should only be
 130  *              used if the caller knows it has some appropriate lock on the
 131  *              index already.)
 132  *
 133  *              An error is raised if the index does not exist.
 134  *
 135  *              This is a convenience routine adapted for indexscan use.
 136  *              Some callers may prefer to use relation_open directly.
 137  * ----------------
 138  */
 139 Relation
 140 index_open(Oid relationId, LOCKMODE lockmode)
 141 {
 142         Relation        r;
 143
 144         r = relation_open(relationId, lockmode);
 145
 146         if (r->rd_rel->relkind != RELKIND_INDEX)
 147                 ereport(ERROR,
 148                                 (errcode(ERRCODE_WRONG_OBJECT_TYPE),
 149                                  errmsg("\"%s\" is not an index",
 150                                                 RelationGetRelationName(r))));
 151
 152         return r;
 153 }
 154
 155 /* ----------------
 156  *              index_close - close an index relation
 157  *
 158  *              If lockmode is not "NoLock", we then release the specified lock.
 159  *
 160  *              Note that it is often sensible to hold a lock beyond index_close;
 161  *              in that case, the lock is released automatically at xact end.
 162  * ----------------
 163  */
 164 void
 165 index_close(Relation relation, LOCKMODE lockmode)
 166 {
 167         LockRelId       relid = relation->rd_lockInfo.lockRelId;
 168
 169         Assert(lockmode >= NoLock && lockmode < MAX_LOCKMODES);
 170
 171         /* The relcache does the real work... */
 172         RelationClose(relation);
 173
 174         if (lockmode != NoLock)
 175                 UnlockRelationId(&relid, lockmode);
 176 }
 177
 178 /* ----------------
 179  *              index_insert - insert an index tuple into a relation
 180  * ----------------
 181  */
 182 bool
 183 index_insert(Relation indexRelation,
 184                          Datum *values,
 185                          bool *isnull,
 186                          ItemPointer heap_t_ctid,
 187                          Relation heapRelation,
 188                          bool check_uniqueness)
 189 {
 190         FmgrInfo   *procedure;
 191
 192         RELATION_CHECKS;
 193         GET_REL_PROCEDURE(aminsert);
 194
 195         /*
 196          * have the am's insert proc do all the work.
 197          */
 198         return DatumGetBool(FunctionCall6(procedure,
 199                                                                           PointerGetDatum(indexRelation),
 200                                                                           PointerGetDatum(values),
 201                                                                           PointerGetDatum(isnull),
 202                                                                           PointerGetDatum(heap_t_ctid),
 203                                                                           PointerGetDatum(heapRelation),
 204                                                                           BoolGetDatum(check_uniqueness)));
 205 }
 206
 207 /*
 208  * index_beginscan - start a scan of an index with amgettuple
 209  *
 210  * Caller must be holding suitable locks on the heap and the index.
 211  */
 212 IndexScanDesc
 213 index_beginscan(Relation heapRelation,
 214                                 Relation indexRelation,
 215                                 Snapshot snapshot,
 216                                 int nkeys, ScanKey key)
 217 {
 218         IndexScanDesc scan;
 219
 220         scan = index_beginscan_internal(indexRelation, nkeys, key);
 221
 222         /*
 223          * Save additional parameters into the scandesc.  Everything else was set
 224          * up by RelationGetIndexScan.
 225          */
 226         scan->heapRelation = heapRelation;
 227         scan->xs_snapshot = snapshot;
 228
 229         return scan;
 230 }
 231
 232 /*
 233  * index_beginscan_bitmap - start a scan of an index with amgetbitmap
 234  *
 235  * As above, caller had better be holding some lock on the parent heap
 236  * relation, even though it's not explicitly mentioned here.
 237  */
 238 IndexScanDesc
 239 index_beginscan_bitmap(Relation indexRelation,
 240                                            Snapshot snapshot,
 241                                            int nkeys, ScanKey key)
 242 {
 243         IndexScanDesc scan;
 244
 245         scan = index_beginscan_internal(indexRelation, nkeys, key);
 246
 247         /*
 248          * Save additional parameters into the scandesc.  Everything else was set
 249          * up by RelationGetIndexScan.
 250          */
 251         scan->xs_snapshot = snapshot;
 252
 253         return scan;
 254 }
 255
 256 /*
 257  * index_beginscan_internal --- common code for index_beginscan variants
 258  */
 259 static IndexScanDesc
 260 index_beginscan_internal(Relation indexRelation,
 261                                                  int nkeys, ScanKey key)
 262 {
 263         IndexScanDesc scan;
 264         FmgrInfo   *procedure;
 265
 266         RELATION_CHECKS;
 267         GET_REL_PROCEDURE(ambeginscan);
 268
 269         /*
 270          * We hold a reference count to the relcache entry throughout the scan.
 271          */
 272         RelationIncrementReferenceCount(indexRelation);
 273
 274         /*
 275          * Tell the AM to open a scan.
 276          */
 277         scan = (IndexScanDesc)
 278                 DatumGetPointer(FunctionCall3(procedure,
 279                                                                           PointerGetDatum(indexRelation),
 280                                                                           Int32GetDatum(nkeys),
 281                                                                           PointerGetDatum(key)));
 282
 283         return scan;
 284 }
 285
 286 /* ----------------
 287  *              index_rescan  - (re)start a scan of an index
 288  *
 289  * The caller may specify a new set of scankeys (but the number of keys
 290  * cannot change).      To restart the scan without changing keys, pass NULL
 291  * for the key array.
 292  *
 293  * Note that this is also called when first starting an indexscan;
 294  * see RelationGetIndexScan.  Keys *must* be passed in that case,
 295  * unless scan->numberOfKeys is zero.
 296  * ----------------
 297  */
 298 void
 299 index_rescan(IndexScanDesc scan, ScanKey key)
 300 {
 301         FmgrInfo   *procedure;
 302
 303         SCAN_CHECKS;
 304         GET_SCAN_PROCEDURE(amrescan);
 305
 306         /* Release any held pin on a heap page */
 307         if (BufferIsValid(scan->xs_cbuf))
 308         {
 309                 ReleaseBuffer(scan->xs_cbuf);
 310                 scan->xs_cbuf = InvalidBuffer;
 311         }
 312
 313         scan->xs_next_hot = InvalidOffsetNumber;
 314
 315         scan->kill_prior_tuple = false;         /* for safety */
 316
 317         FunctionCall2(procedure,
 318                                   PointerGetDatum(scan),
 319                                   PointerGetDatum(key));
 320 }
 321
 322 /* ----------------
 323  *              index_endscan - end a scan
 324  * ----------------
 325  */
 326 void
 327 index_endscan(IndexScanDesc scan)
 328 {
 329         FmgrInfo   *procedure;
 330
 331         SCAN_CHECKS;
 332         GET_SCAN_PROCEDURE(amendscan);
 333
 334         /* Release any held pin on a heap page */
 335         if (BufferIsValid(scan->xs_cbuf))
 336         {
 337                 ReleaseBuffer(scan->xs_cbuf);
 338                 scan->xs_cbuf = InvalidBuffer;
 339         }
 340
 341         /* End the AM's scan */
 342         FunctionCall1(procedure, PointerGetDatum(scan));
 343
 344         /* Release index refcount acquired by index_beginscan */
 345         RelationDecrementReferenceCount(scan->indexRelation);
 346
 347         /* Release the scan data structure itself */
 348         IndexScanEnd(scan);
 349 }
 350
 351 /* ----------------
 352  *              index_markpos  - mark a scan position
 353  * ----------------
 354  */
 355 void
 356 index_markpos(IndexScanDesc scan)
 357 {
 358         FmgrInfo   *procedure;
 359
 360         SCAN_CHECKS;
 361         GET_SCAN_PROCEDURE(ammarkpos);
 362
 363         FunctionCall1(procedure, PointerGetDatum(scan));
 364 }
 365
 366 /* ----------------
 367  *              index_restrpos  - restore a scan position
 368  *
 369  * NOTE: this only restores the internal scan state of the index AM.
 370  * The current result tuple (scan->xs_ctup) doesn't change.  See comments
 371  * for ExecRestrPos().
 372  *
 373  * NOTE: in the presence of HOT chains, mark/restore only works correctly
 374  * if the scan's snapshot is MVCC-safe; that ensures that there's at most one
 375  * returnable tuple in each HOT chain, and so restoring the prior state at the
 376  * granularity of the index AM is sufficient.  Since the only current user
 377  * of mark/restore functionality is nodeMergejoin.c, this effectively means
 378  * that merge-join plans only work for MVCC snapshots.  This could be fixed
 379  * if necessary, but for now it seems unimportant.
 380  * ----------------
 381  */
 382 void
 383 index_restrpos(IndexScanDesc scan)
 384 {
 385         FmgrInfo   *procedure;
 386
 387         Assert(IsMVCCSnapshot(scan->xs_snapshot));
 388
 389         SCAN_CHECKS;
 390         GET_SCAN_PROCEDURE(amrestrpos);
 391
 392         scan->xs_next_hot = InvalidOffsetNumber;
 393
 394         scan->kill_prior_tuple = false;         /* for safety */
 395
 396         FunctionCall1(procedure, PointerGetDatum(scan));
 397 }
 398
 399 /* ----------------
 400  *              index_getnext - get the next heap tuple from a scan
 401  *
 402  * The result is the next heap tuple satisfying the scan keys and the
 403  * snapshot, or NULL if no more matching tuples exist.  On success,
 404  * the buffer containing the heap tuple is pinned (the pin will be dropped
 405  * at the next index_getnext or index_endscan).
 406  *
 407  * Note: caller must check scan->xs_recheck, and perform rechecking of the
 408  * scan keys if required.  We do not do that here because we don't have
 409  * enough information to do it efficiently in the general case.
 410  * ----------------
 411  */
 412 HeapTuple
 413 index_getnext(IndexScanDesc scan, ScanDirection direction)
 414 {
 415         HeapTuple       heapTuple = &scan->xs_ctup;
 416         ItemPointer tid = &heapTuple->t_self;
 417         FmgrInfo   *procedure;
 418
 419         SCAN_CHECKS;
 420         GET_SCAN_PROCEDURE(amgettuple);
 421
 422         /*
 423          * We always reset xs_hot_dead; if we are here then either we are just
 424          * starting the scan, or we previously returned a visible tuple, and in
 425          * either case it's inappropriate to kill the prior index entry.
 426          */
 427         scan->xs_hot_dead = false;
 428
 429         for (;;)
 430         {
 431                 OffsetNumber offnum;
 432                 bool            at_chain_start;
 433                 Page            dp;
 434
 435                 if (scan->xs_next_hot != InvalidOffsetNumber)
 436                 {
 437                         /*
 438                          * We are resuming scan of a HOT chain after having returned an
 439                          * earlier member.      Must still hold pin on current heap page.
 440                          */
 441                         Assert(BufferIsValid(scan->xs_cbuf));
 442                         Assert(ItemPointerGetBlockNumber(tid) ==
 443                                    BufferGetBlockNumber(scan->xs_cbuf));
 444                         Assert(TransactionIdIsValid(scan->xs_prev_xmax));
 445                         offnum = scan->xs_next_hot;
 446                         at_chain_start = false;
 447                         scan->xs_next_hot = InvalidOffsetNumber;
 448                 }
 449                 else
 450                 {
 451                         bool            found;
 452                         Buffer          prev_buf;
 453
 454                         /*
 455                          * If we scanned a whole HOT chain and found only dead tuples,
 456                          * tell index AM to kill its entry for that TID.
 457                          */
 458                         scan->kill_prior_tuple = scan->xs_hot_dead;
 459
 460                         /*
 461                          * The AM's gettuple proc finds the next index entry matching the
 462                          * scan keys, and puts the TID in xs_ctup.t_self (ie, *tid).
 463                          * It should also set scan->xs_recheck, though we pay no
 464                          * attention to that here.
 465                          */
 466                         found = DatumGetBool(FunctionCall2(procedure,
 467                                                                                            PointerGetDatum(scan),
 468                                                                                            Int32GetDatum(direction)));
 469
 470                         /* Reset kill flag immediately for safety */
 471                         scan->kill_prior_tuple = false;
 472
 473                         /* If we're out of index entries, break out of outer loop */
 474                         if (!found)
 475                                 break;
 476
 477                         pgstat_count_index_tuples(scan->indexRelation, 1);
 478
 479                         /* Switch to correct buffer if we don't have it already */
 480                         prev_buf = scan->xs_cbuf;
 481                         scan->xs_cbuf = ReleaseAndReadBuffer(scan->xs_cbuf,
 482                                                                                                  scan->heapRelation,
 483                                                                                          ItemPointerGetBlockNumber(tid));
 484
 485                         /*
 486                          * Prune page, but only if we weren't already on this page
 487                          */
 488                         if (prev_buf != scan->xs_cbuf)
 489                                 heap_page_prune_opt(scan->heapRelation, scan->xs_cbuf,
 490                                                                         RecentGlobalXmin);
 491
 492                         /* Prepare to scan HOT chain starting at index-referenced offnum */
 493                         offnum = ItemPointerGetOffsetNumber(tid);
 494                         at_chain_start = true;
 495
 496                         /* We don't know what the first tuple's xmin should be */
 497                         scan->xs_prev_xmax = InvalidTransactionId;
 498
 499                         /* Initialize flag to detect if all entries are dead */
 500                         scan->xs_hot_dead = true;
 501                 }
 502
 503                 /* Obtain share-lock on the buffer so we can examine visibility */
 504                 LockBuffer(scan->xs_cbuf, BUFFER_LOCK_SHARE);
 505
 506                 dp = (Page) BufferGetPage(scan->xs_cbuf);
 507
 508                 /* Scan through possible multiple members of HOT-chain */
 509                 for (;;)
 510                 {
 511                         ItemId          lp;
 512                         ItemPointer ctid;
 513
 514                         /* check for bogus TID */
 515                         if (offnum < FirstOffsetNumber ||
 516                                 offnum > PageGetMaxOffsetNumber(dp))
 517                                 break;
 518
 519                         lp = PageGetItemId(dp, offnum);
 520
 521                         /* check for unused, dead, or redirected items */
 522                         if (!ItemIdIsNormal(lp))
 523                         {
 524                                 /* We should only see a redirect at start of chain */
 525                                 if (ItemIdIsRedirected(lp) && at_chain_start)
 526                                 {
 527                                         /* Follow the redirect */
 528                                         offnum = ItemIdGetRedirect(lp);
 529                                         at_chain_start = false;
 530                                         continue;
 531                                 }
 532                                 /* else must be end of chain */
 533                                 break;
 534                         }
 535
 536                         /*
 537                          * We must initialize all of *heapTuple (ie, scan->xs_ctup) since
 538                          * it is returned to the executor on success.
 539                          */
 540                         heapTuple->t_data = (HeapTupleHeader) PageGetItem(dp, lp);
 541                         heapTuple->t_len = ItemIdGetLength(lp);
 542                         ItemPointerSetOffsetNumber(tid, offnum);
 543                         heapTuple->t_tableOid = RelationGetRelid(scan->heapRelation);
 544                         ctid = &heapTuple->t_data->t_ctid;
 545
 546                         /*
 547                          * Shouldn't see a HEAP_ONLY tuple at chain start.  (This test
 548                          * should be unnecessary, since the chain root can't be removed
 549                          * while we have pin on the index entry, but let's make it
 550                          * anyway.)
 551                          */
 552                         if (at_chain_start && HeapTupleIsHeapOnly(heapTuple))
 553                                 break;
 554
 555                         /*
 556                          * The xmin should match the previous xmax value, else chain is
 557                          * broken.      (Note: this test is not optional because it protects
 558                          * us against the case where the prior chain member's xmax aborted
 559                          * since we looked at it.)
 560                          */
 561                         if (TransactionIdIsValid(scan->xs_prev_xmax) &&
 562                                 !TransactionIdEquals(scan->xs_prev_xmax,
 563                                                                   HeapTupleHeaderGetXmin(heapTuple->t_data)))
 564                                 break;
 565
 566                         /* If it's visible per the snapshot, we must return it */
 567                         if (HeapTupleSatisfiesVisibility(heapTuple, scan->xs_snapshot,
 568                                                                                          scan->xs_cbuf))
 569                         {
 570                                 /*
 571                                  * If the snapshot is MVCC, we know that it could accept at
 572                                  * most one member of the HOT chain, so we can skip examining
 573                                  * any more members.  Otherwise, check for continuation of the
 574                                  * HOT-chain, and set state for next time.
 575                                  */
 576                                 if (IsMVCCSnapshot(scan->xs_snapshot))
 577                                         scan->xs_next_hot = InvalidOffsetNumber;
 578                                 else if (HeapTupleIsHotUpdated(heapTuple))
 579                                 {
 580                                         Assert(ItemPointerGetBlockNumber(ctid) ==
 581                                                    ItemPointerGetBlockNumber(tid));
 582                                         scan->xs_next_hot = ItemPointerGetOffsetNumber(ctid);
 583                                         scan->xs_prev_xmax = HeapTupleHeaderGetXmax(heapTuple->t_data);
 584                                 }
 585                                 else
 586                                         scan->xs_next_hot = InvalidOffsetNumber;
 587
 588                                 LockBuffer(scan->xs_cbuf, BUFFER_LOCK_UNLOCK);
 589
 590                                 pgstat_count_heap_fetch(scan->indexRelation);
 591
 592                                 return heapTuple;
 593                         }
 594
 595                         /*
 596                          * If we can't see it, maybe no one else can either.  Check to see
 597                          * if the tuple is dead to all transactions.  If we find that all
 598                          * the tuples in the HOT chain are dead, we'll signal the index AM
 599                          * to not return that TID on future indexscans.
 600                          */
 601                         if (scan->xs_hot_dead &&
 602                                 HeapTupleSatisfiesVacuum(heapTuple->t_data, RecentGlobalXmin,
 603                                                                                  scan->xs_cbuf) != HEAPTUPLE_DEAD)
 604                                 scan->xs_hot_dead = false;
 605
 606                         /*
 607                          * Check to see if HOT chain continues past this tuple; if so
 608                          * fetch the next offnum (we don't bother storing it into
 609                          * xs_next_hot, but must store xs_prev_xmax), and loop around.
 610                          */
 611                         if (HeapTupleIsHotUpdated(heapTuple))
 612                         {
 613                                 Assert(ItemPointerGetBlockNumber(ctid) ==
 614                                            ItemPointerGetBlockNumber(tid));
 615                                 offnum = ItemPointerGetOffsetNumber(ctid);
 616                                 at_chain_start = false;
 617                                 scan->xs_prev_xmax = HeapTupleHeaderGetXmax(heapTuple->t_data);
 618                         }
 619                         else
 620                                 break;                  /* end of chain */
 621                 }                                               /* loop over a single HOT chain */
 622
 623                 LockBuffer(scan->xs_cbuf, BUFFER_LOCK_UNLOCK);
 624
 625                 /* Loop around to ask index AM for another TID */
 626                 scan->xs_next_hot = InvalidOffsetNumber;
 627         }
 628
 629         /* Release any held pin on a heap page */
 630         if (BufferIsValid(scan->xs_cbuf))
 631         {
 632                 ReleaseBuffer(scan->xs_cbuf);
 633                 scan->xs_cbuf = InvalidBuffer;
 634         }
 635
 636         return NULL;                            /* failure exit */
 637 }
 638
 639 /* ----------------
 640  *              index_getbitmap - get all tuples at once from an index scan
 641  *
 642  * Adds the TIDs of all heap tuples satisfying the scan keys to a bitmap.
 643  * Since there's no interlock between the index scan and the eventual heap
 644  * access, this is only safe to use with MVCC-based snapshots: the heap
 645  * item slot could have been replaced by a newer tuple by the time we get
 646  * to it.
 647  *
 648  * Returns the number of matching tuples found.
 649  * ----------------
 650  */
 651 int64
 652 index_getbitmap(IndexScanDesc scan, TIDBitmap *bitmap)
 653 {
 654         FmgrInfo   *procedure;
 655         int64           ntids;
 656
 657         SCAN_CHECKS;
 658         GET_SCAN_PROCEDURE(amgetbitmap);
 659
 660         /* just make sure this is false... */
 661         scan->kill_prior_tuple = false;
 662
 663         /*
 664          * have the am's getbitmap proc do all the work.
 665          */
 666         ntids = DatumGetInt64(FunctionCall2(procedure,
 667                                                                                 PointerGetDatum(scan),
 668                                                                                 PointerGetDatum(bitmap)));
 669
 670         pgstat_count_index_tuples(scan->indexRelation, ntids);
 671
 672         return ntids;
 673 }
 674
 675 /* ----------------
 676  *              index_bulk_delete - do mass deletion of index entries
 677  *
 678  *              callback routine tells whether a given main-heap tuple is
 679  *              to be deleted
 680  *
 681  *              return value is an optional palloc'd struct of statistics
 682  * ----------------
 683  */
 684 IndexBulkDeleteResult *
 685 index_bulk_delete(IndexVacuumInfo *info,
 686                                   IndexBulkDeleteResult *stats,
 687                                   IndexBulkDeleteCallback callback,
 688                                   void *callback_state)
 689 {
 690         Relation        indexRelation = info->index;
 691         FmgrInfo   *procedure;
 692         IndexBulkDeleteResult *result;
 693
 694         RELATION_CHECKS;
 695         GET_REL_PROCEDURE(ambulkdelete);
 696
 697         result = (IndexBulkDeleteResult *)
 698                 DatumGetPointer(FunctionCall4(procedure,
 699                                                                           PointerGetDatum(info),
 700                                                                           PointerGetDatum(stats),
 701                                                                           PointerGetDatum((Pointer) callback),
 702                                                                           PointerGetDatum(callback_state)));
 703
 704         return result;
 705 }
 706
 707 /* ----------------
 708  *              index_vacuum_cleanup - do post-deletion cleanup of an index
 709  *
 710  *              return value is an optional palloc'd struct of statistics
 711  * ----------------
 712  */
 713 IndexBulkDeleteResult *
 714 index_vacuum_cleanup(IndexVacuumInfo *info,
 715                                          IndexBulkDeleteResult *stats)
 716 {
 717         Relation        indexRelation = info->index;
 718         FmgrInfo   *procedure;
 719         IndexBulkDeleteResult *result;
 720
 721         RELATION_CHECKS;
 722         GET_REL_PROCEDURE(amvacuumcleanup);
 723
 724         result = (IndexBulkDeleteResult *)
 725                 DatumGetPointer(FunctionCall2(procedure,
 726                                                                           PointerGetDatum(info),
 727                                                                           PointerGetDatum(stats)));
 728
 729         return result;
 730 }
 731
 732 /* ----------------
 733  *              index_getprocid
 734  *
 735  *              Index access methods typically require support routines that are
 736  *              not directly the implementation of any WHERE-clause query operator
 737  *              and so cannot be kept in pg_amop.  Instead, such routines are kept
 738  *              in pg_amproc.  These registered procedure OIDs are assigned numbers
 739  *              according to a convention established by the access method.
 740  *              The general index code doesn't know anything about the routines
 741  *              involved; it just builds an ordered list of them for
 742  *              each attribute on which an index is defined.
 743  *
 744  *              As of Postgres 8.3, support routines within an operator family
 745  *              are further subdivided by the "left type" and "right type" of the
 746  *              query operator(s) that they support.  The "default" functions for a
 747  *              particular indexed attribute are those with both types equal to
 748  *              the index opclass' opcintype (note that this is subtly different
 749  *              from the indexed attribute's own type: it may be a binary-compatible
 750  *              type instead).  Only the default functions are stored in relcache
 751  *              entries --- access methods can use the syscache to look up non-default
 752  *              functions.
 753  *
 754  *              This routine returns the requested default procedure OID for a
 755  *              particular indexed attribute.
 756  * ----------------
 757  */
 758 RegProcedure
 759 index_getprocid(Relation irel,
 760                                 AttrNumber attnum,
 761                                 uint16 procnum)
 762 {
 763         RegProcedure *loc;
 764         int                     nproc;
 765         int                     procindex;
 766
 767         nproc = irel->rd_am->amsupport;
 768
 769         Assert(procnum > 0 && procnum <= (uint16) nproc);
 770
 771         procindex = (nproc * (attnum - 1)) + (procnum - 1);
 772
 773         loc = irel->rd_support;
 774
 775         Assert(loc != NULL);
 776
 777         return loc[procindex];
 778 }
 779
 780 /* ----------------
 781  *              index_getprocinfo
 782  *
 783  *              This routine allows index AMs to keep fmgr lookup info for
 784  *              support procs in the relcache.  As above, only the "default"
 785  *              functions for any particular indexed attribute are cached.
 786  *
 787  * Note: the return value points into cached data that will be lost during
 788  * any relcache rebuild!  Therefore, either use the callinfo right away,
 789  * or save it only after having acquired some type of lock on the index rel.
 790  * ----------------
 791  */
 792 FmgrInfo *
 793 index_getprocinfo(Relation irel,
 794                                   AttrNumber attnum,
 795                                   uint16 procnum)
 796 {
 797         FmgrInfo   *locinfo;
 798         int                     nproc;
 799         int                     procindex;
 800
 801         nproc = irel->rd_am->amsupport;
 802
 803         Assert(procnum > 0 && procnum <= (uint16) nproc);
 804
 805         procindex = (nproc * (attnum - 1)) + (procnum - 1);
 806
 807         locinfo = irel->rd_supportinfo;
 808
 809         Assert(locinfo != NULL);
 810
 811         locinfo += procindex;
 812
 813         /* Initialize the lookup info if first time through */
 814         if (locinfo->fn_oid == InvalidOid)
 815         {
 816                 RegProcedure *loc = irel->rd_support;
 817                 RegProcedure procId;
 818
 819                 Assert(loc != NULL);
 820
 821                 procId = loc[procindex];
 822
 823                 /*
 824                  * Complain if function was not found during IndexSupportInitialize.
 825                  * This should not happen unless the system tables contain bogus
 826                  * entries for the index opclass.  (If an AM wants to allow a support
 827                  * function to be optional, it can use index_getprocid.)
 828                  */
 829                 if (!RegProcedureIsValid(procId))
 830                         elog(ERROR, "missing support function %d for attribute %d of index \"%s\"",
 831                                  procnum, attnum, RelationGetRelationName(irel));
 832
 833                 fmgr_info_cxt(procId, locinfo, irel->rd_indexcxt);
 834         }
 835
 836         return locinfo;
 837 }