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) 1996-2012, PostgreSQL Global Development Group
   7  * Portions Copyright (c) 1994, Regents of the University of California
   8  *
   9  *
  10  * IDENTIFICATION
  11  *        src/backend/access/index/indexam.c
  12  *
  13  * INTERFACE ROUTINES
  14  *              index_open              - open an index relation by relation OID
  15  *              index_close             - close an index relation
  16  *              index_beginscan - start a scan of an index with amgettuple
  17  *              index_beginscan_bitmap - start a scan of an index with amgetbitmap
  18  *              index_rescan    - restart a scan of an index
  19  *              index_endscan   - end a scan
  20  *              index_insert    - insert an index tuple into a relation
  21  *              index_markpos   - mark a scan position
  22  *              index_restrpos  - restore a scan position
  23  *              index_getnext_tid       - get the next TID from a scan
  24  *              index_fetch_heap                - get the scan's next heap tuple
  25  *              index_getnext   - get the next heap tuple from a scan
  26  *              index_getbitmap - get all tuples from a scan
  27  *              index_bulk_delete       - bulk deletion of index tuples
  28  *              index_vacuum_cleanup    - post-deletion cleanup of an index
  29  *              index_can_return        - does index support index-only scans?
  30  *              index_getprocid - get a support procedure OID
  31  *              index_getprocinfo - get a support procedure's lookup info
  32  *
  33  * NOTES
  34  *              This file contains the index_ routines which used
  35  *              to be a scattered collection of stuff in access/genam.
  36  *
  37  *
  38  * old comments
  39  *              Scans are implemented as follows:
  40  *
  41  *              `0' represents an invalid item pointer.
  42  *              `-' represents an unknown item pointer.
  43  *              `X' represents a known item pointers.
  44  *              `+' represents known or invalid item pointers.
  45  *              `*' represents any item pointers.
  46  *
  47  *              State is represented by a triple of these symbols in the order of
  48  *              previous, current, next.  Note that the case of reverse scans works
  49  *              identically.
  50  *
  51  *                              State   Result
  52  *              (1)             + + -   + 0 0                   (if the next item pointer is invalid)
  53  *              (2)                             + X -                   (otherwise)
  54  *              (3)             * 0 0   * 0 0                   (no change)
  55  *              (4)             + X 0   X 0 0                   (shift)
  56  *              (5)             * + X   + X -                   (shift, add unknown)
  57  *
  58  *              All other states cannot occur.
  59  *
  60  *              Note: It would be possible to cache the status of the previous and
  61  *                        next item pointer using the flags.
  62  *
  63  *-------------------------------------------------------------------------
  64  */
  65
  66 #include "postgres.h"
  67
  68 #include "access/relscan.h"
  69 #include "access/transam.h"
  70 #include "catalog/index.h"
  71 #include "pgstat.h"
  72 #include "storage/bufmgr.h"
  73 #include "storage/lmgr.h"
  74 #include "storage/predicate.h"
  75 #include "utils/snapmgr.h"
  76 #include "utils/tqual.h"
  77
  78
  79 /* ----------------------------------------------------------------
  80  *                                      macros used in index_ routines
  81  *
  82  * Note: the ReindexIsProcessingIndex() check in RELATION_CHECKS is there
  83  * to check that we don't try to scan or do retail insertions into an index
  84  * that is currently being rebuilt or pending rebuild.  This helps to catch
  85  * things that don't work when reindexing system catalogs.  The assertion
  86  * doesn't prevent the actual rebuild because we don't use RELATION_CHECKS
  87  * when calling the index AM's ambuild routine, and there is no reason for
  88  * ambuild to call its subsidiary routines through this file.
  89  * ----------------------------------------------------------------
  90  */
  91 #define RELATION_CHECKS \
  92 ( \
  93         AssertMacro(RelationIsValid(indexRelation)), \
  94         AssertMacro(PointerIsValid(indexRelation->rd_am)), \
  95         AssertMacro(!ReindexIsProcessingIndex(RelationGetRelid(indexRelation))) \
  96 )
  97
  98 #define SCAN_CHECKS \
  99 ( \
 100         AssertMacro(IndexScanIsValid(scan)), \
 101         AssertMacro(RelationIsValid(scan->indexRelation)), \
 102         AssertMacro(PointerIsValid(scan->indexRelation->rd_am)) \
 103 )
 104
 105 #define GET_REL_PROCEDURE(pname) \
 106 do { \
 107         procedure = &indexRelation->rd_aminfo->pname; \
 108         if (!OidIsValid(procedure->fn_oid)) \
 109         { \
 110                 RegProcedure    procOid = indexRelation->rd_am->pname; \
 111                 if (!RegProcedureIsValid(procOid)) \
 112                         elog(ERROR, "invalid %s regproc", CppAsString(pname)); \
 113                 fmgr_info_cxt(procOid, procedure, indexRelation->rd_indexcxt); \
 114         } \
 115 } while(0)
 116
 117 #define GET_SCAN_PROCEDURE(pname) \
 118 do { \
 119         procedure = &scan->indexRelation->rd_aminfo->pname; \
 120         if (!OidIsValid(procedure->fn_oid)) \
 121         { \
 122                 RegProcedure    procOid = scan->indexRelation->rd_am->pname; \
 123                 if (!RegProcedureIsValid(procOid)) \
 124                         elog(ERROR, "invalid %s regproc", CppAsString(pname)); \
 125                 fmgr_info_cxt(procOid, procedure, scan->indexRelation->rd_indexcxt); \
 126         } \
 127 } while(0)
 128
 129 static IndexScanDesc index_beginscan_internal(Relation indexRelation,
 130                                                  int nkeys, int norderbys, Snapshot snapshot);
 131
 132
 133 /* ----------------------------------------------------------------
 134  *                                 index_ interface functions
 135  * ----------------------------------------------------------------
 136  */
 137
 138 /* ----------------
 139  *              index_open - open an index relation by relation OID
 140  *
 141  *              If lockmode is not "NoLock", the specified kind of lock is
 142  *              obtained on the index.  (Generally, NoLock should only be
 143  *              used if the caller knows it has some appropriate lock on the
 144  *              index already.)
 145  *
 146  *              An error is raised if the index does not exist.
 147  *
 148  *              This is a convenience routine adapted for indexscan use.
 149  *              Some callers may prefer to use relation_open directly.
 150  * ----------------
 151  */
 152 Relation
 153 index_open(Oid relationId, LOCKMODE lockmode)
 154 {
 155         Relation        r;
 156
 157         r = relation_open(relationId, lockmode);
 158
 159         if (r->rd_rel->relkind != RELKIND_INDEX)
 160                 ereport(ERROR,
 161                                 (errcode(ERRCODE_WRONG_OBJECT_TYPE),
 162                                  errmsg("\"%s\" is not an index",
 163                                                 RelationGetRelationName(r))));
 164
 165         return r;
 166 }
 167
 168 /* ----------------
 169  *              index_close - close an index relation
 170  *
 171  *              If lockmode is not "NoLock", we then release the specified lock.
 172  *
 173  *              Note that it is often sensible to hold a lock beyond index_close;
 174  *              in that case, the lock is released automatically at xact end.
 175  * ----------------
 176  */
 177 void
 178 index_close(Relation relation, LOCKMODE lockmode)
 179 {
 180         LockRelId       relid = relation->rd_lockInfo.lockRelId;
 181
 182         Assert(lockmode >= NoLock && lockmode < MAX_LOCKMODES);
 183
 184         /* The relcache does the real work... */
 185         RelationClose(relation);
 186
 187         if (lockmode != NoLock)
 188                 UnlockRelationId(&relid, lockmode);
 189 }
 190
 191 /* ----------------
 192  *              index_insert - insert an index tuple into a relation
 193  * ----------------
 194  */
 195 bool
 196 index_insert(Relation indexRelation,
 197                          Datum *values,
 198                          bool *isnull,
 199                          ItemPointer heap_t_ctid,
 200                          Relation heapRelation,
 201                          IndexUniqueCheck checkUnique)
 202 {
 203         FmgrInfo   *procedure;
 204
 205         RELATION_CHECKS;
 206         GET_REL_PROCEDURE(aminsert);
 207
 208         if (!(indexRelation->rd_am->ampredlocks))
 209                 CheckForSerializableConflictIn(indexRelation,
 210                                                                            (HeapTuple) NULL,
 211                                                                            InvalidBuffer);
 212
 213         /*
 214          * have the am's insert proc do all the work.
 215          */
 216         return DatumGetBool(FunctionCall6(procedure,
 217                                                                           PointerGetDatum(indexRelation),
 218                                                                           PointerGetDatum(values),
 219                                                                           PointerGetDatum(isnull),
 220                                                                           PointerGetDatum(heap_t_ctid),
 221                                                                           PointerGetDatum(heapRelation),
 222                                                                           Int32GetDatum((int32) checkUnique)));
 223 }
 224
 225 /*
 226  * index_beginscan - start a scan of an index with amgettuple
 227  *
 228  * Caller must be holding suitable locks on the heap and the index.
 229  */
 230 IndexScanDesc
 231 index_beginscan(Relation heapRelation,
 232                                 Relation indexRelation,
 233                                 Snapshot snapshot,
 234                                 int nkeys, int norderbys)
 235 {
 236         IndexScanDesc scan;
 237
 238         scan = index_beginscan_internal(indexRelation, nkeys, norderbys, snapshot);
 239
 240         /*
 241          * Save additional parameters into the scandesc.  Everything else was set
 242          * up by RelationGetIndexScan.
 243          */
 244         scan->heapRelation = heapRelation;
 245         scan->xs_snapshot = snapshot;
 246
 247         return scan;
 248 }
 249
 250 /*
 251  * index_beginscan_bitmap - start a scan of an index with amgetbitmap
 252  *
 253  * As above, caller had better be holding some lock on the parent heap
 254  * relation, even though it's not explicitly mentioned here.
 255  */
 256 IndexScanDesc
 257 index_beginscan_bitmap(Relation indexRelation,
 258                                            Snapshot snapshot,
 259                                            int nkeys)
 260 {
 261         IndexScanDesc scan;
 262
 263         scan = index_beginscan_internal(indexRelation, nkeys, 0, snapshot);
 264
 265         /*
 266          * Save additional parameters into the scandesc.  Everything else was set
 267          * up by RelationGetIndexScan.
 268          */
 269         scan->xs_snapshot = snapshot;
 270
 271         return scan;
 272 }
 273
 274 /*
 275  * index_beginscan_internal --- common code for index_beginscan variants
 276  */
 277 static IndexScanDesc
 278 index_beginscan_internal(Relation indexRelation,
 279                                                  int nkeys, int norderbys, Snapshot snapshot)
 280 {
 281         IndexScanDesc scan;
 282         FmgrInfo   *procedure;
 283
 284         RELATION_CHECKS;
 285         GET_REL_PROCEDURE(ambeginscan);
 286
 287         if (!(indexRelation->rd_am->ampredlocks))
 288                 PredicateLockRelation(indexRelation, snapshot);
 289
 290         /*
 291          * We hold a reference count to the relcache entry throughout the scan.
 292          */
 293         RelationIncrementReferenceCount(indexRelation);
 294
 295         /*
 296          * Tell the AM to open a scan.
 297          */
 298         scan = (IndexScanDesc)
 299                 DatumGetPointer(FunctionCall3(procedure,
 300                                                                           PointerGetDatum(indexRelation),
 301                                                                           Int32GetDatum(nkeys),
 302                                                                           Int32GetDatum(norderbys)));
 303
 304         return scan;
 305 }
 306
 307 /* ----------------
 308  *              index_rescan  - (re)start a scan of an index
 309  *
 310  * During a restart, the caller may specify a new set of scankeys and/or
 311  * orderbykeys; but the number of keys cannot differ from what index_beginscan
 312  * was told.  (Later we might relax that to "must not exceed", but currently
 313  * the index AMs tend to assume that scan->numberOfKeys is what to believe.)
 314  * To restart the scan without changing keys, pass NULL for the key arrays.
 315  * (Of course, keys *must* be passed on the first call, unless
 316  * scan->numberOfKeys is zero.)
 317  * ----------------
 318  */
 319 void
 320 index_rescan(IndexScanDesc scan,
 321                          ScanKey keys, int nkeys,
 322                          ScanKey orderbys, int norderbys)
 323 {
 324         FmgrInfo   *procedure;
 325
 326         SCAN_CHECKS;
 327         GET_SCAN_PROCEDURE(amrescan);
 328
 329         Assert(nkeys == scan->numberOfKeys);
 330         Assert(norderbys == scan->numberOfOrderBys);
 331
 332         /* Release any held pin on a heap page */
 333         if (BufferIsValid(scan->xs_cbuf))
 334         {
 335                 ReleaseBuffer(scan->xs_cbuf);
 336                 scan->xs_cbuf = InvalidBuffer;
 337         }
 338
 339         scan->xs_continue_hot = false;
 340
 341         scan->kill_prior_tuple = false;         /* for safety */
 342
 343         FunctionCall5(procedure,
 344                                   PointerGetDatum(scan),
 345                                   PointerGetDatum(keys),
 346                                   Int32GetDatum(nkeys),
 347                                   PointerGetDatum(orderbys),
 348                                   Int32GetDatum(norderbys));
 349 }
 350
 351 /* ----------------
 352  *              index_endscan - end a scan
 353  * ----------------
 354  */
 355 void
 356 index_endscan(IndexScanDesc scan)
 357 {
 358         FmgrInfo   *procedure;
 359
 360         SCAN_CHECKS;
 361         GET_SCAN_PROCEDURE(amendscan);
 362
 363         /* Release any held pin on a heap page */
 364         if (BufferIsValid(scan->xs_cbuf))
 365         {
 366                 ReleaseBuffer(scan->xs_cbuf);
 367                 scan->xs_cbuf = InvalidBuffer;
 368         }
 369
 370         /* End the AM's scan */
 371         FunctionCall1(procedure, PointerGetDatum(scan));
 372
 373         /* Release index refcount acquired by index_beginscan */
 374         RelationDecrementReferenceCount(scan->indexRelation);
 375
 376         /* Release the scan data structure itself */
 377         IndexScanEnd(scan);
 378 }
 379
 380 /* ----------------
 381  *              index_markpos  - mark a scan position
 382  * ----------------
 383  */
 384 void
 385 index_markpos(IndexScanDesc scan)
 386 {
 387         FmgrInfo   *procedure;
 388
 389         SCAN_CHECKS;
 390         GET_SCAN_PROCEDURE(ammarkpos);
 391
 392         FunctionCall1(procedure, PointerGetDatum(scan));
 393 }
 394
 395 /* ----------------
 396  *              index_restrpos  - restore a scan position
 397  *
 398  * NOTE: this only restores the internal scan state of the index AM.
 399  * The current result tuple (scan->xs_ctup) doesn't change.  See comments
 400  * for ExecRestrPos().
 401  *
 402  * NOTE: in the presence of HOT chains, mark/restore only works correctly
 403  * if the scan's snapshot is MVCC-safe; that ensures that there's at most one
 404  * returnable tuple in each HOT chain, and so restoring the prior state at the
 405  * granularity of the index AM is sufficient.  Since the only current user
 406  * of mark/restore functionality is nodeMergejoin.c, this effectively means
 407  * that merge-join plans only work for MVCC snapshots.  This could be fixed
 408  * if necessary, but for now it seems unimportant.
 409  * ----------------
 410  */
 411 void
 412 index_restrpos(IndexScanDesc scan)
 413 {
 414         FmgrInfo   *procedure;
 415
 416         Assert(IsMVCCSnapshot(scan->xs_snapshot));
 417
 418         SCAN_CHECKS;
 419         GET_SCAN_PROCEDURE(amrestrpos);
 420
 421         scan->xs_continue_hot = false;
 422
 423         scan->kill_prior_tuple = false;         /* for safety */
 424
 425         FunctionCall1(procedure, PointerGetDatum(scan));
 426 }
 427
 428 /* ----------------
 429  * index_getnext_tid - get the next TID from a scan
 430  *
 431  * The result is the next TID satisfying the scan keys,
 432  * or NULL if no more matching tuples exist.
 433  * ----------------
 434  */
 435 ItemPointer
 436 index_getnext_tid(IndexScanDesc scan, ScanDirection direction)
 437 {
 438         FmgrInfo   *procedure;
 439         bool            found;
 440
 441         SCAN_CHECKS;
 442         GET_SCAN_PROCEDURE(amgettuple);
 443
 444         Assert(TransactionIdIsValid(RecentGlobalXmin));
 445
 446         /*
 447          * The AM's amgettuple proc finds the next index entry matching the scan
 448          * keys, and puts the TID into scan->xs_ctup.t_self.  It should also set
 449          * scan->xs_recheck and possibly scan->xs_itup, though we pay no attention
 450          * to those fields here.
 451          */
 452         found = DatumGetBool(FunctionCall2(procedure,
 453                                                                            PointerGetDatum(scan),
 454                                                                            Int32GetDatum(direction)));
 455
 456         /* Reset kill flag immediately for safety */
 457         scan->kill_prior_tuple = false;
 458
 459         /* If we're out of index entries, we're done */
 460         if (!found)
 461         {
 462                 /* ... but first, release any held pin on a heap page */
 463                 if (BufferIsValid(scan->xs_cbuf))
 464                 {
 465                         ReleaseBuffer(scan->xs_cbuf);
 466                         scan->xs_cbuf = InvalidBuffer;
 467                 }
 468                 return NULL;
 469         }
 470
 471         pgstat_count_index_tuples(scan->indexRelation, 1);
 472
 473         /* Return the TID of the tuple we found. */
 474         return &scan->xs_ctup.t_self;
 475 }
 476
 477 /* ----------------
 478  *              index_fetch_heap - get the scan's next heap tuple
 479  *
 480  * The result is a visible heap tuple associated with the index TID most
 481  * recently fetched by index_getnext_tid, or NULL if no more matching tuples
 482  * exist.  (There can be more than one matching tuple because of HOT chains,
 483  * although when using an MVCC snapshot it should be impossible for more than
 484  * one such tuple to exist.)
 485  *
 486  * On success, the buffer containing the heap tup is pinned (the pin will be
 487  * dropped in a future index_getnext_tid, index_fetch_heap or index_endscan
 488  * call).
 489  *
 490  * Note: caller must check scan->xs_recheck, and perform rechecking of the
 491  * scan keys if required.  We do not do that here because we don't have
 492  * enough information to do it efficiently in the general case.
 493  * ----------------
 494  */
 495 HeapTuple
 496 index_fetch_heap(IndexScanDesc scan)
 497 {
 498         ItemPointer tid = &scan->xs_ctup.t_self;
 499         bool            all_dead = false;
 500         bool            got_heap_tuple;
 501
 502         /* We can skip the buffer-switching logic if we're in mid-HOT chain. */
 503         if (!scan->xs_continue_hot)
 504         {
 505                 /* Switch to correct buffer if we don't have it already */
 506                 Buffer          prev_buf = scan->xs_cbuf;
 507
 508                 scan->xs_cbuf = ReleaseAndReadBuffer(scan->xs_cbuf,
 509                                                                                          scan->heapRelation,
 510                                                                                          ItemPointerGetBlockNumber(tid));
 511
 512                 /*
 513                  * Prune page, but only if we weren't already on this page
 514                  */
 515                 if (prev_buf != scan->xs_cbuf)
 516                         heap_page_prune_opt(scan->heapRelation, scan->xs_cbuf,
 517                                                                 RecentGlobalXmin);
 518         }
 519
 520         /* Obtain share-lock on the buffer so we can examine visibility */
 521         LockBuffer(scan->xs_cbuf, BUFFER_LOCK_SHARE);
 522         got_heap_tuple = heap_hot_search_buffer(tid, scan->heapRelation,
 523                                                                                         scan->xs_cbuf,
 524                                                                                         scan->xs_snapshot,
 525                                                                                         &scan->xs_ctup,
 526                                                                                         &all_dead,
 527                                                                                         !scan->xs_continue_hot);
 528         LockBuffer(scan->xs_cbuf, BUFFER_LOCK_UNLOCK);
 529
 530         if (got_heap_tuple)
 531         {
 532                 /*
 533                  * Only in a non-MVCC snapshot can more than one member of the HOT
 534                  * chain be visible.
 535                  */
 536                 scan->xs_continue_hot = !IsMVCCSnapshot(scan->xs_snapshot);
 537                 pgstat_count_heap_fetch(scan->indexRelation);
 538                 return &scan->xs_ctup;
 539         }
 540
 541         /* We've reached the end of the HOT chain. */
 542         scan->xs_continue_hot = false;
 543
 544         /*
 545          * If we scanned a whole HOT chain and found only dead tuples, tell index
 546          * AM to kill its entry for that TID (this will take effect in the next
 547          * amgettuple call, in index_getnext_tid).      We do not do this when in
 548          * recovery because it may violate MVCC to do so.  See comments in
 549          * RelationGetIndexScan().
 550          */
 551         if (!scan->xactStartedInRecovery)
 552                 scan->kill_prior_tuple = all_dead;
 553
 554         return NULL;
 555 }
 556
 557 /* ----------------
 558  *              index_getnext - get the next heap tuple from a scan
 559  *
 560  * The result is the next heap tuple satisfying the scan keys and the
 561  * snapshot, or NULL if no more matching tuples exist.
 562  *
 563  * On success, the buffer containing the heap tup is pinned (the pin will be
 564  * dropped in a future index_getnext_tid, index_fetch_heap or index_endscan
 565  * call).
 566  *
 567  * Note: caller must check scan->xs_recheck, and perform rechecking of the
 568  * scan keys if required.  We do not do that here because we don't have
 569  * enough information to do it efficiently in the general case.
 570  * ----------------
 571  */
 572 HeapTuple
 573 index_getnext(IndexScanDesc scan, ScanDirection direction)
 574 {
 575         HeapTuple       heapTuple;
 576         ItemPointer tid;
 577
 578         for (;;)
 579         {
 580                 if (scan->xs_continue_hot)
 581                 {
 582                         /*
 583                          * We are resuming scan of a HOT chain after having returned an
 584                          * earlier member.      Must still hold pin on current heap page.
 585                          */
 586                         Assert(BufferIsValid(scan->xs_cbuf));
 587                         Assert(ItemPointerGetBlockNumber(&scan->xs_ctup.t_self) ==
 588                                    BufferGetBlockNumber(scan->xs_cbuf));
 589                 }
 590                 else
 591                 {
 592                         /* Time to fetch the next TID from the index */
 593                         tid = index_getnext_tid(scan, direction);
 594
 595                         /* If we're out of index entries, we're done */
 596                         if (tid == NULL)
 597                                 break;
 598                 }
 599
 600                 /*
 601                  * Fetch the next (or only) visible heap tuple for this index entry.
 602                  * If we don't find anything, loop around and grab the next TID from
 603                  * the index.
 604                  */
 605                 heapTuple = index_fetch_heap(scan);
 606                 if (heapTuple != NULL)
 607                         return heapTuple;
 608         }
 609
 610         return NULL;                            /* failure exit */
 611 }
 612
 613 /* ----------------
 614  *              index_getbitmap - get all tuples at once from an index scan
 615  *
 616  * Adds the TIDs of all heap tuples satisfying the scan keys to a bitmap.
 617  * Since there's no interlock between the index scan and the eventual heap
 618  * access, this is only safe to use with MVCC-based snapshots: the heap
 619  * item slot could have been replaced by a newer tuple by the time we get
 620  * to it.
 621  *
 622  * Returns the number of matching tuples found.  (Note: this might be only
 623  * approximate, so it should only be used for statistical purposes.)
 624  * ----------------
 625  */
 626 int64
 627 index_getbitmap(IndexScanDesc scan, TIDBitmap *bitmap)
 628 {
 629         FmgrInfo   *procedure;
 630         int64           ntids;
 631         Datum           d;
 632
 633         SCAN_CHECKS;
 634         GET_SCAN_PROCEDURE(amgetbitmap);
 635
 636         /* just make sure this is false... */
 637         scan->kill_prior_tuple = false;
 638
 639         /*
 640          * have the am's getbitmap proc do all the work.
 641          */
 642         d = FunctionCall2(procedure,
 643                                           PointerGetDatum(scan),
 644                                           PointerGetDatum(bitmap));
 645
 646         ntids = DatumGetInt64(d);
 647
 648         /* If int8 is pass-by-ref, must free the result to avoid memory leak */
 649 #ifndef USE_FLOAT8_BYVAL
 650         pfree(DatumGetPointer(d));
 651 #endif
 652
 653         pgstat_count_index_tuples(scan->indexRelation, ntids);
 654
 655         return ntids;
 656 }
 657
 658 /* ----------------
 659  *              index_bulk_delete - do mass deletion of index entries
 660  *
 661  *              callback routine tells whether a given main-heap tuple is
 662  *              to be deleted
 663  *
 664  *              return value is an optional palloc'd struct of statistics
 665  * ----------------
 666  */
 667 IndexBulkDeleteResult *
 668 index_bulk_delete(IndexVacuumInfo *info,
 669                                   IndexBulkDeleteResult *stats,
 670                                   IndexBulkDeleteCallback callback,
 671                                   void *callback_state)
 672 {
 673         Relation        indexRelation = info->index;
 674         FmgrInfo   *procedure;
 675         IndexBulkDeleteResult *result;
 676
 677         RELATION_CHECKS;
 678         GET_REL_PROCEDURE(ambulkdelete);
 679
 680         result = (IndexBulkDeleteResult *)
 681                 DatumGetPointer(FunctionCall4(procedure,
 682                                                                           PointerGetDatum(info),
 683                                                                           PointerGetDatum(stats),
 684                                                                           PointerGetDatum((Pointer) callback),
 685                                                                           PointerGetDatum(callback_state)));
 686
 687         return result;
 688 }
 689
 690 /* ----------------
 691  *              index_vacuum_cleanup - do post-deletion cleanup of an index
 692  *
 693  *              return value is an optional palloc'd struct of statistics
 694  * ----------------
 695  */
 696 IndexBulkDeleteResult *
 697 index_vacuum_cleanup(IndexVacuumInfo *info,
 698                                          IndexBulkDeleteResult *stats)
 699 {
 700         Relation        indexRelation = info->index;
 701         FmgrInfo   *procedure;
 702         IndexBulkDeleteResult *result;
 703
 704         RELATION_CHECKS;
 705         GET_REL_PROCEDURE(amvacuumcleanup);
 706
 707         result = (IndexBulkDeleteResult *)
 708                 DatumGetPointer(FunctionCall2(procedure,
 709                                                                           PointerGetDatum(info),
 710                                                                           PointerGetDatum(stats)));
 711
 712         return result;
 713 }
 714
 715 /* ----------------
 716  *              index_can_return - does index support index-only scans?
 717  * ----------------
 718  */
 719 bool
 720 index_can_return(Relation indexRelation)
 721 {
 722         FmgrInfo   *procedure;
 723
 724         RELATION_CHECKS;
 725
 726         /* amcanreturn is optional; assume FALSE if not provided by AM */
 727         if (!RegProcedureIsValid(indexRelation->rd_am->amcanreturn))
 728                 return false;
 729
 730         GET_REL_PROCEDURE(amcanreturn);
 731
 732         return DatumGetBool(FunctionCall1(procedure,
 733                                                                           PointerGetDatum(indexRelation)));
 734 }
 735
 736 /* ----------------
 737  *              index_getprocid
 738  *
 739  *              Index access methods typically require support routines that are
 740  *              not directly the implementation of any WHERE-clause query operator
 741  *              and so cannot be kept in pg_amop.  Instead, such routines are kept
 742  *              in pg_amproc.  These registered procedure OIDs are assigned numbers
 743  *              according to a convention established by the access method.
 744  *              The general index code doesn't know anything about the routines
 745  *              involved; it just builds an ordered list of them for
 746  *              each attribute on which an index is defined.
 747  *
 748  *              As of Postgres 8.3, support routines within an operator family
 749  *              are further subdivided by the "left type" and "right type" of the
 750  *              query operator(s) that they support.  The "default" functions for a
 751  *              particular indexed attribute are those with both types equal to
 752  *              the index opclass' opcintype (note that this is subtly different
 753  *              from the indexed attribute's own type: it may be a binary-compatible
 754  *              type instead).  Only the default functions are stored in relcache
 755  *              entries --- access methods can use the syscache to look up non-default
 756  *              functions.
 757  *
 758  *              This routine returns the requested default procedure OID for a
 759  *              particular indexed attribute.
 760  * ----------------
 761  */
 762 RegProcedure
 763 index_getprocid(Relation irel,
 764                                 AttrNumber attnum,
 765                                 uint16 procnum)
 766 {
 767         RegProcedure *loc;
 768         int                     nproc;
 769         int                     procindex;
 770
 771         nproc = irel->rd_am->amsupport;
 772
 773         Assert(procnum > 0 && procnum <= (uint16) nproc);
 774
 775         procindex = (nproc * (attnum - 1)) + (procnum - 1);
 776
 777         loc = irel->rd_support;
 778
 779         Assert(loc != NULL);
 780
 781         return loc[procindex];
 782 }
 783
 784 /* ----------------
 785  *              index_getprocinfo
 786  *
 787  *              This routine allows index AMs to keep fmgr lookup info for
 788  *              support procs in the relcache.  As above, only the "default"
 789  *              functions for any particular indexed attribute are cached.
 790  *
 791  * Note: the return value points into cached data that will be lost during
 792  * any relcache rebuild!  Therefore, either use the callinfo right away,
 793  * or save it only after having acquired some type of lock on the index rel.
 794  * ----------------
 795  */
 796 FmgrInfo *
 797 index_getprocinfo(Relation irel,
 798                                   AttrNumber attnum,
 799                                   uint16 procnum)
 800 {
 801         FmgrInfo   *locinfo;
 802         int                     nproc;
 803         int                     procindex;
 804
 805         nproc = irel->rd_am->amsupport;
 806
 807         Assert(procnum > 0 && procnum <= (uint16) nproc);
 808
 809         procindex = (nproc * (attnum - 1)) + (procnum - 1);
 810
 811         locinfo = irel->rd_supportinfo;
 812
 813         Assert(locinfo != NULL);
 814
 815         locinfo += procindex;
 816
 817         /* Initialize the lookup info if first time through */
 818         if (locinfo->fn_oid == InvalidOid)
 819         {
 820                 RegProcedure *loc = irel->rd_support;
 821                 RegProcedure procId;
 822
 823                 Assert(loc != NULL);
 824
 825                 procId = loc[procindex];
 826
 827                 /*
 828                  * Complain if function was not found during IndexSupportInitialize.
 829                  * This should not happen unless the system tables contain bogus
 830                  * entries for the index opclass.  (If an AM wants to allow a support
 831                  * function to be optional, it can use index_getprocid.)
 832                  */
 833                 if (!RegProcedureIsValid(procId))
 834                         elog(ERROR, "missing support function %d for attribute %d of index \"%s\"",
 835                                  procnum, attnum, RelationGetRelationName(irel));
 836
 837                 fmgr_info_cxt(procId, locinfo, irel->rd_indexcxt);
 838         }
 839
 840         return locinfo;
 841 }