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) 1996-2009, 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 1.116 2009/12/19 01:32:32 sriggs 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                          IndexUniqueCheck checkUnique)
 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                                                                           Int32GetDatum((int32) checkUnique)));
 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         Assert(TransactionIdIsValid(RecentGlobalXmin));
 423
 424         /*
 425          * We always reset xs_hot_dead; if we are here then either we are just
 426          * starting the scan, or we previously returned a visible tuple, and in
 427          * either case it's inappropriate to kill the prior index entry.
 428          */
 429         scan->xs_hot_dead = false;
 430
 431         for (;;)
 432         {
 433                 OffsetNumber offnum;
 434                 bool            at_chain_start;
 435                 Page            dp;
 436
 437                 if (scan->xs_next_hot != InvalidOffsetNumber)
 438                 {
 439                         /*
 440                          * We are resuming scan of a HOT chain after having returned an
 441                          * earlier member.      Must still hold pin on current heap page.
 442                          */
 443                         Assert(BufferIsValid(scan->xs_cbuf));
 444                         Assert(ItemPointerGetBlockNumber(tid) ==
 445                                    BufferGetBlockNumber(scan->xs_cbuf));
 446                         Assert(TransactionIdIsValid(scan->xs_prev_xmax));
 447                         offnum = scan->xs_next_hot;
 448                         at_chain_start = false;
 449                         scan->xs_next_hot = InvalidOffsetNumber;
 450                 }
 451                 else
 452                 {
 453                         bool            found;
 454                         Buffer          prev_buf;
 455
 456                         /*
 457                          * If we scanned a whole HOT chain and found only dead tuples,
 458                          * tell index AM to kill its entry for that TID. We do not do
 459                          * this when in recovery because it may violate MVCC to do so.
 460                          * see comments in RelationGetIndexScan().
 461                          */
 462                         if (!scan->xactStartedInRecovery)
 463                                 scan->kill_prior_tuple = scan->xs_hot_dead;
 464
 465                         /*
 466                          * The AM's gettuple proc finds the next index entry matching the
 467                          * scan keys, and puts the TID in xs_ctup.t_self (ie, *tid). It
 468                          * should also set scan->xs_recheck, though we pay no attention to
 469                          * that here.
 470                          */
 471                         found = DatumGetBool(FunctionCall2(procedure,
 472                                                                                            PointerGetDatum(scan),
 473                                                                                            Int32GetDatum(direction)));
 474
 475                         /* Reset kill flag immediately for safety */
 476                         scan->kill_prior_tuple = false;
 477
 478                         /* If we're out of index entries, break out of outer loop */
 479                         if (!found)
 480                                 break;
 481
 482                         pgstat_count_index_tuples(scan->indexRelation, 1);
 483
 484                         /* Switch to correct buffer if we don't have it already */
 485                         prev_buf = scan->xs_cbuf;
 486                         scan->xs_cbuf = ReleaseAndReadBuffer(scan->xs_cbuf,
 487                                                                                                  scan->heapRelation,
 488                                                                                          ItemPointerGetBlockNumber(tid));
 489
 490                         /*
 491                          * Prune page, but only if we weren't already on this page
 492                          */
 493                         if (prev_buf != scan->xs_cbuf)
 494                                 heap_page_prune_opt(scan->heapRelation, scan->xs_cbuf,
 495                                                                         RecentGlobalXmin);
 496
 497                         /* Prepare to scan HOT chain starting at index-referenced offnum */
 498                         offnum = ItemPointerGetOffsetNumber(tid);
 499                         at_chain_start = true;
 500
 501                         /* We don't know what the first tuple's xmin should be */
 502                         scan->xs_prev_xmax = InvalidTransactionId;
 503
 504                         /* Initialize flag to detect if all entries are dead */
 505                         scan->xs_hot_dead = true;
 506                 }
 507
 508                 /* Obtain share-lock on the buffer so we can examine visibility */
 509                 LockBuffer(scan->xs_cbuf, BUFFER_LOCK_SHARE);
 510
 511                 dp = (Page) BufferGetPage(scan->xs_cbuf);
 512
 513                 /* Scan through possible multiple members of HOT-chain */
 514                 for (;;)
 515                 {
 516                         ItemId          lp;
 517                         ItemPointer ctid;
 518
 519                         /* check for bogus TID */
 520                         if (offnum < FirstOffsetNumber ||
 521                                 offnum > PageGetMaxOffsetNumber(dp))
 522                                 break;
 523
 524                         lp = PageGetItemId(dp, offnum);
 525
 526                         /* check for unused, dead, or redirected items */
 527                         if (!ItemIdIsNormal(lp))
 528                         {
 529                                 /* We should only see a redirect at start of chain */
 530                                 if (ItemIdIsRedirected(lp) && at_chain_start)
 531                                 {
 532                                         /* Follow the redirect */
 533                                         offnum = ItemIdGetRedirect(lp);
 534                                         at_chain_start = false;
 535                                         continue;
 536                                 }
 537                                 /* else must be end of chain */
 538                                 break;
 539                         }
 540
 541                         /*
 542                          * We must initialize all of *heapTuple (ie, scan->xs_ctup) since
 543                          * it is returned to the executor on success.
 544                          */
 545                         heapTuple->t_data = (HeapTupleHeader) PageGetItem(dp, lp);
 546                         heapTuple->t_len = ItemIdGetLength(lp);
 547                         ItemPointerSetOffsetNumber(tid, offnum);
 548                         heapTuple->t_tableOid = RelationGetRelid(scan->heapRelation);
 549                         ctid = &heapTuple->t_data->t_ctid;
 550
 551                         /*
 552                          * Shouldn't see a HEAP_ONLY tuple at chain start.  (This test
 553                          * should be unnecessary, since the chain root can't be removed
 554                          * while we have pin on the index entry, but let's make it
 555                          * anyway.)
 556                          */
 557                         if (at_chain_start && HeapTupleIsHeapOnly(heapTuple))
 558                                 break;
 559
 560                         /*
 561                          * The xmin should match the previous xmax value, else chain is
 562                          * broken.      (Note: this test is not optional because it protects
 563                          * us against the case where the prior chain member's xmax aborted
 564                          * since we looked at it.)
 565                          */
 566                         if (TransactionIdIsValid(scan->xs_prev_xmax) &&
 567                                 !TransactionIdEquals(scan->xs_prev_xmax,
 568                                                                   HeapTupleHeaderGetXmin(heapTuple->t_data)))
 569                                 break;
 570
 571                         /* If it's visible per the snapshot, we must return it */
 572                         if (HeapTupleSatisfiesVisibility(heapTuple, scan->xs_snapshot,
 573                                                                                          scan->xs_cbuf))
 574                         {
 575                                 /*
 576                                  * If the snapshot is MVCC, we know that it could accept at
 577                                  * most one member of the HOT chain, so we can skip examining
 578                                  * any more members.  Otherwise, check for continuation of the
 579                                  * HOT-chain, and set state for next time.
 580                                  */
 581                                 if (IsMVCCSnapshot(scan->xs_snapshot))
 582                                         scan->xs_next_hot = InvalidOffsetNumber;
 583                                 else if (HeapTupleIsHotUpdated(heapTuple))
 584                                 {
 585                                         Assert(ItemPointerGetBlockNumber(ctid) ==
 586                                                    ItemPointerGetBlockNumber(tid));
 587                                         scan->xs_next_hot = ItemPointerGetOffsetNumber(ctid);
 588                                         scan->xs_prev_xmax = HeapTupleHeaderGetXmax(heapTuple->t_data);
 589                                 }
 590                                 else
 591                                         scan->xs_next_hot = InvalidOffsetNumber;
 592
 593                                 LockBuffer(scan->xs_cbuf, BUFFER_LOCK_UNLOCK);
 594
 595                                 pgstat_count_heap_fetch(scan->indexRelation);
 596
 597                                 return heapTuple;
 598                         }
 599
 600                         /*
 601                          * If we can't see it, maybe no one else can either.  Check to see
 602                          * if the tuple is dead to all transactions.  If we find that all
 603                          * the tuples in the HOT chain are dead, we'll signal the index AM
 604                          * to not return that TID on future indexscans.
 605                          */
 606                         if (scan->xs_hot_dead &&
 607                                 HeapTupleSatisfiesVacuum(heapTuple->t_data, RecentGlobalXmin,
 608                                                                                  scan->xs_cbuf) != HEAPTUPLE_DEAD)
 609                                 scan->xs_hot_dead = false;
 610
 611                         /*
 612                          * Check to see if HOT chain continues past this tuple; if so
 613                          * fetch the next offnum (we don't bother storing it into
 614                          * xs_next_hot, but must store xs_prev_xmax), and loop around.
 615                          */
 616                         if (HeapTupleIsHotUpdated(heapTuple))
 617                         {
 618                                 Assert(ItemPointerGetBlockNumber(ctid) ==
 619                                            ItemPointerGetBlockNumber(tid));
 620                                 offnum = ItemPointerGetOffsetNumber(ctid);
 621                                 at_chain_start = false;
 622                                 scan->xs_prev_xmax = HeapTupleHeaderGetXmax(heapTuple->t_data);
 623                         }
 624                         else
 625                                 break;                  /* end of chain */
 626                 }                                               /* loop over a single HOT chain */
 627
 628                 LockBuffer(scan->xs_cbuf, BUFFER_LOCK_UNLOCK);
 629
 630                 /* Loop around to ask index AM for another TID */
 631                 scan->xs_next_hot = InvalidOffsetNumber;
 632         }
 633
 634         /* Release any held pin on a heap page */
 635         if (BufferIsValid(scan->xs_cbuf))
 636         {
 637                 ReleaseBuffer(scan->xs_cbuf);
 638                 scan->xs_cbuf = InvalidBuffer;
 639         }
 640
 641         return NULL;                            /* failure exit */
 642 }
 643
 644 /* ----------------
 645  *              index_getbitmap - get all tuples at once from an index scan
 646  *
 647  * Adds the TIDs of all heap tuples satisfying the scan keys to a bitmap.
 648  * Since there's no interlock between the index scan and the eventual heap
 649  * access, this is only safe to use with MVCC-based snapshots: the heap
 650  * item slot could have been replaced by a newer tuple by the time we get
 651  * to it.
 652  *
 653  * Returns the number of matching tuples found.  (Note: this might be only
 654  * approximate, so it should only be used for statistical purposes.)
 655  * ----------------
 656  */
 657 int64
 658 index_getbitmap(IndexScanDesc scan, TIDBitmap *bitmap)
 659 {
 660         FmgrInfo   *procedure;
 661         int64           ntids;
 662         Datum           d;
 663
 664         SCAN_CHECKS;
 665         GET_SCAN_PROCEDURE(amgetbitmap);
 666
 667         /* just make sure this is false... */
 668         scan->kill_prior_tuple = false;
 669
 670         /*
 671          * have the am's getbitmap proc do all the work.
 672          */
 673         d = FunctionCall2(procedure,
 674                                           PointerGetDatum(scan),
 675                                           PointerGetDatum(bitmap));
 676
 677         ntids = DatumGetInt64(d);
 678
 679         /* If int8 is pass-by-ref, must free the result to avoid memory leak */
 680 #ifndef USE_FLOAT8_BYVAL
 681         pfree(DatumGetPointer(d));
 682 #endif
 683
 684         pgstat_count_index_tuples(scan->indexRelation, ntids);
 685
 686         return ntids;
 687 }
 688
 689 /* ----------------
 690  *              index_bulk_delete - do mass deletion of index entries
 691  *
 692  *              callback routine tells whether a given main-heap tuple is
 693  *              to be deleted
 694  *
 695  *              return value is an optional palloc'd struct of statistics
 696  * ----------------
 697  */
 698 IndexBulkDeleteResult *
 699 index_bulk_delete(IndexVacuumInfo *info,
 700                                   IndexBulkDeleteResult *stats,
 701                                   IndexBulkDeleteCallback callback,
 702                                   void *callback_state)
 703 {
 704         Relation        indexRelation = info->index;
 705         FmgrInfo   *procedure;
 706         IndexBulkDeleteResult *result;
 707
 708         RELATION_CHECKS;
 709         GET_REL_PROCEDURE(ambulkdelete);
 710
 711         result = (IndexBulkDeleteResult *)
 712                 DatumGetPointer(FunctionCall4(procedure,
 713                                                                           PointerGetDatum(info),
 714                                                                           PointerGetDatum(stats),
 715                                                                           PointerGetDatum((Pointer) callback),
 716                                                                           PointerGetDatum(callback_state)));
 717
 718         return result;
 719 }
 720
 721 /* ----------------
 722  *              index_vacuum_cleanup - do post-deletion cleanup of an index
 723  *
 724  *              return value is an optional palloc'd struct of statistics
 725  * ----------------
 726  */
 727 IndexBulkDeleteResult *
 728 index_vacuum_cleanup(IndexVacuumInfo *info,
 729                                          IndexBulkDeleteResult *stats)
 730 {
 731         Relation        indexRelation = info->index;
 732         FmgrInfo   *procedure;
 733         IndexBulkDeleteResult *result;
 734
 735         RELATION_CHECKS;
 736         GET_REL_PROCEDURE(amvacuumcleanup);
 737
 738         result = (IndexBulkDeleteResult *)
 739                 DatumGetPointer(FunctionCall2(procedure,
 740                                                                           PointerGetDatum(info),
 741                                                                           PointerGetDatum(stats)));
 742
 743         return result;
 744 }
 745
 746 /* ----------------
 747  *              index_getprocid
 748  *
 749  *              Index access methods typically require support routines that are
 750  *              not directly the implementation of any WHERE-clause query operator
 751  *              and so cannot be kept in pg_amop.  Instead, such routines are kept
 752  *              in pg_amproc.  These registered procedure OIDs are assigned numbers
 753  *              according to a convention established by the access method.
 754  *              The general index code doesn't know anything about the routines
 755  *              involved; it just builds an ordered list of them for
 756  *              each attribute on which an index is defined.
 757  *
 758  *              As of Postgres 8.3, support routines within an operator family
 759  *              are further subdivided by the "left type" and "right type" of the
 760  *              query operator(s) that they support.  The "default" functions for a
 761  *              particular indexed attribute are those with both types equal to
 762  *              the index opclass' opcintype (note that this is subtly different
 763  *              from the indexed attribute's own type: it may be a binary-compatible
 764  *              type instead).  Only the default functions are stored in relcache
 765  *              entries --- access methods can use the syscache to look up non-default
 766  *              functions.
 767  *
 768  *              This routine returns the requested default procedure OID for a
 769  *              particular indexed attribute.
 770  * ----------------
 771  */
 772 RegProcedure
 773 index_getprocid(Relation irel,
 774                                 AttrNumber attnum,
 775                                 uint16 procnum)
 776 {
 777         RegProcedure *loc;
 778         int                     nproc;
 779         int                     procindex;
 780
 781         nproc = irel->rd_am->amsupport;
 782
 783         Assert(procnum > 0 && procnum <= (uint16) nproc);
 784
 785         procindex = (nproc * (attnum - 1)) + (procnum - 1);
 786
 787         loc = irel->rd_support;
 788
 789         Assert(loc != NULL);
 790
 791         return loc[procindex];
 792 }
 793
 794 /* ----------------
 795  *              index_getprocinfo
 796  *
 797  *              This routine allows index AMs to keep fmgr lookup info for
 798  *              support procs in the relcache.  As above, only the "default"
 799  *              functions for any particular indexed attribute are cached.
 800  *
 801  * Note: the return value points into cached data that will be lost during
 802  * any relcache rebuild!  Therefore, either use the callinfo right away,
 803  * or save it only after having acquired some type of lock on the index rel.
 804  * ----------------
 805  */
 806 FmgrInfo *
 807 index_getprocinfo(Relation irel,
 808                                   AttrNumber attnum,
 809                                   uint16 procnum)
 810 {
 811         FmgrInfo   *locinfo;
 812         int                     nproc;
 813         int                     procindex;
 814
 815         nproc = irel->rd_am->amsupport;
 816
 817         Assert(procnum > 0 && procnum <= (uint16) nproc);
 818
 819         procindex = (nproc * (attnum - 1)) + (procnum - 1);
 820
 821         locinfo = irel->rd_supportinfo;
 822
 823         Assert(locinfo != NULL);
 824
 825         locinfo += procindex;
 826
 827         /* Initialize the lookup info if first time through */
 828         if (locinfo->fn_oid == InvalidOid)
 829         {
 830                 RegProcedure *loc = irel->rd_support;
 831                 RegProcedure procId;
 832
 833                 Assert(loc != NULL);
 834
 835                 procId = loc[procindex];
 836
 837                 /*
 838                  * Complain if function was not found during IndexSupportInitialize.
 839                  * This should not happen unless the system tables contain bogus
 840                  * entries for the index opclass.  (If an AM wants to allow a support
 841                  * function to be optional, it can use index_getprocid.)
 842                  */
 843                 if (!RegProcedureIsValid(procId))
 844                         elog(ERROR, "missing support function %d for attribute %d of index \"%s\"",
 845                                  procnum, attnum, RelationGetRelationName(irel));
 846
 847                 fmgr_info_cxt(procId, locinfo, irel->rd_indexcxt);
 848         }
 849
 850         return locinfo;
 851 }