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) 1996-2007, 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 1.98 2007/05/27 03:50:38 tgl Exp $
  12  *
  13  * INTERFACE ROUTINES
  14  *              index_open              - open an index relation by relation OID
  15  *              index_close             - close an index relation
  16  *              index_beginscan - start a scan of an index with amgettuple
  17  *              index_beginscan_multi - start a scan of an index with amgetmulti
  18  *              index_rescan    - restart a scan of an index
  19  *              index_endscan   - end a scan
  20  *              index_insert    - insert an index tuple into a relation
  21  *              index_markpos   - mark a scan position
  22  *              index_restrpos  - restore a scan position
  23  *              index_getnext   - get the next tuple from a scan
  24  *              index_getmulti  - get multiple tuples from a scan
  25  *              index_bulk_delete       - bulk deletion of index tuples
  26  *              index_vacuum_cleanup    - post-deletion cleanup of an index
  27  *              index_getprocid - get a support procedure OID
  28  *              index_getprocinfo - get a support procedure's lookup info
  29  *
  30  * NOTES
  31  *              This file contains the index_ routines which used
  32  *              to be a scattered collection of stuff in access/genam.
  33  *
  34  *
  35  * old comments
  36  *              Scans are implemented as follows:
  37  *
  38  *              `0' represents an invalid item pointer.
  39  *              `-' represents an unknown item pointer.
  40  *              `X' represents a known item pointers.
  41  *              `+' represents known or invalid item pointers.
  42  *              `*' represents any item pointers.
  43  *
  44  *              State is represented by a triple of these symbols in the order of
  45  *              previous, current, next.  Note that the case of reverse scans works
  46  *              identically.
  47  *
  48  *                              State   Result
  49  *              (1)             + + -   + 0 0                   (if the next item pointer is invalid)
  50  *              (2)                             + X -                   (otherwise)
  51  *              (3)             * 0 0   * 0 0                   (no change)
  52  *              (4)             + X 0   X 0 0                   (shift)
  53  *              (5)             * + X   + X -                   (shift, add unknown)
  54  *
  55  *              All other states cannot occur.
  56  *
  57  *              Note: It would be possible to cache the status of the previous and
  58  *                        next item pointer using the flags.
  59  *
  60  *-------------------------------------------------------------------------
  61  */
  62
  63 #include "postgres.h"
  64
  65 #include "access/genam.h"
  66 #include "access/heapam.h"
  67 #include "pgstat.h"
  68 #include "utils/relcache.h"
  69
  70
  71 /* ----------------------------------------------------------------
  72  *                                      macros used in index_ routines
  73  * ----------------------------------------------------------------
  74  */
  75 #define RELATION_CHECKS \
  76 ( \
  77         AssertMacro(RelationIsValid(indexRelation)), \
  78         AssertMacro(PointerIsValid(indexRelation->rd_am)) \
  79 )
  80
  81 #define SCAN_CHECKS \
  82 ( \
  83         AssertMacro(IndexScanIsValid(scan)), \
  84         AssertMacro(RelationIsValid(scan->indexRelation)), \
  85         AssertMacro(PointerIsValid(scan->indexRelation->rd_am)) \
  86 )
  87
  88 #define GET_REL_PROCEDURE(pname) \
  89 do { \
  90         procedure = &indexRelation->rd_aminfo->pname; \
  91         if (!OidIsValid(procedure->fn_oid)) \
  92         { \
  93                 RegProcedure    procOid = indexRelation->rd_am->pname; \
  94                 if (!RegProcedureIsValid(procOid)) \
  95                         elog(ERROR, "invalid %s regproc", CppAsString(pname)); \
  96                 fmgr_info_cxt(procOid, procedure, indexRelation->rd_indexcxt); \
  97         } \
  98 } while(0)
  99
 100 #define GET_SCAN_PROCEDURE(pname) \
 101 do { \
 102         procedure = &scan->indexRelation->rd_aminfo->pname; \
 103         if (!OidIsValid(procedure->fn_oid)) \
 104         { \
 105                 RegProcedure    procOid = scan->indexRelation->rd_am->pname; \
 106                 if (!RegProcedureIsValid(procOid)) \
 107                         elog(ERROR, "invalid %s regproc", CppAsString(pname)); \
 108                 fmgr_info_cxt(procOid, procedure, scan->indexRelation->rd_indexcxt); \
 109         } \
 110 } while(0)
 111
 112 static IndexScanDesc index_beginscan_internal(Relation indexRelation,
 113                                                  int nkeys, ScanKey key);
 114
 115
 116 /* ----------------------------------------------------------------
 117  *                                 index_ interface functions
 118  * ----------------------------------------------------------------
 119  */
 120
 121 /* ----------------
 122  *              index_open - open an index relation by relation OID
 123  *
 124  *              If lockmode is not "NoLock", the specified kind of lock is
 125  *              obtained on the index.  (Generally, NoLock should only be
 126  *              used if the caller knows it has some appropriate lock on the
 127  *              index already.)
 128  *
 129  *              An error is raised if the index does not exist.
 130  *
 131  *              This is a convenience routine adapted for indexscan use.
 132  *              Some callers may prefer to use relation_open directly.
 133  * ----------------
 134  */
 135 Relation
 136 index_open(Oid relationId, LOCKMODE lockmode)
 137 {
 138         Relation        r;
 139
 140         r = relation_open(relationId, lockmode);
 141
 142         if (r->rd_rel->relkind != RELKIND_INDEX)
 143                 ereport(ERROR,
 144                                 (errcode(ERRCODE_WRONG_OBJECT_TYPE),
 145                                  errmsg("\"%s\" is not an index",
 146                                                 RelationGetRelationName(r))));
 147
 148         return r;
 149 }
 150
 151 /* ----------------
 152  *              index_close - close an index relation
 153  *
 154  *              If lockmode is not "NoLock", we then release the specified lock.
 155  *
 156  *              Note that it is often sensible to hold a lock beyond index_close;
 157  *              in that case, the lock is released automatically at xact end.
 158  * ----------------
 159  */
 160 void
 161 index_close(Relation relation, LOCKMODE lockmode)
 162 {
 163         LockRelId       relid = relation->rd_lockInfo.lockRelId;
 164
 165         Assert(lockmode >= NoLock && lockmode < MAX_LOCKMODES);
 166
 167         /* The relcache does the real work... */
 168         RelationClose(relation);
 169
 170         if (lockmode != NoLock)
 171                 UnlockRelationId(&relid, lockmode);
 172 }
 173
 174 /* ----------------
 175  *              index_insert - insert an index tuple into a relation
 176  * ----------------
 177  */
 178 bool
 179 index_insert(Relation indexRelation,
 180                          Datum *values,
 181                          bool *isnull,
 182                          ItemPointer heap_t_ctid,
 183                          Relation heapRelation,
 184                          bool check_uniqueness)
 185 {
 186         FmgrInfo   *procedure;
 187
 188         RELATION_CHECKS;
 189         GET_REL_PROCEDURE(aminsert);
 190
 191         /*
 192          * have the am's insert proc do all the work.
 193          */
 194         return DatumGetBool(FunctionCall6(procedure,
 195                                                                           PointerGetDatum(indexRelation),
 196                                                                           PointerGetDatum(values),
 197                                                                           PointerGetDatum(isnull),
 198                                                                           PointerGetDatum(heap_t_ctid),
 199                                                                           PointerGetDatum(heapRelation),
 200                                                                           BoolGetDatum(check_uniqueness)));
 201 }
 202
 203 /*
 204  * index_beginscan - start a scan of an index with amgettuple
 205  *
 206  * Note: heapRelation may be NULL if there is no intention of calling
 207  * index_getnext on this scan; index_getnext_indexitem will not use the
 208  * heapRelation link (nor the snapshot).  However, the caller had better
 209  * be holding some kind of lock on the heap relation in any case, to ensure
 210  * no one deletes it (or the index) out from under us.  Caller must also
 211  * be holding a lock on the index.
 212  */
 213 IndexScanDesc
 214 index_beginscan(Relation heapRelation,
 215                                 Relation indexRelation,
 216                                 Snapshot snapshot,
 217                                 int nkeys, ScanKey key)
 218 {
 219         IndexScanDesc scan;
 220
 221         scan = index_beginscan_internal(indexRelation, nkeys, key);
 222
 223         /*
 224          * Save additional parameters into the scandesc.  Everything else was set
 225          * up by RelationGetIndexScan.
 226          */
 227         scan->is_multiscan = false;
 228         scan->heapRelation = heapRelation;
 229         scan->xs_snapshot = snapshot;
 230
 231         return scan;
 232 }
 233
 234 /*
 235  * index_beginscan_multi - start a scan of an index with amgetmulti
 236  *
 237  * As above, caller had better be holding some lock on the parent heap
 238  * relation, even though it's not explicitly mentioned here.
 239  */
 240 IndexScanDesc
 241 index_beginscan_multi(Relation indexRelation,
 242                                           Snapshot snapshot,
 243                                           int nkeys, ScanKey key)
 244 {
 245         IndexScanDesc scan;
 246
 247         scan = index_beginscan_internal(indexRelation, nkeys, key);
 248
 249         /*
 250          * Save additional parameters into the scandesc.  Everything else was set
 251          * up by RelationGetIndexScan.
 252          */
 253         scan->is_multiscan = true;
 254         scan->xs_snapshot = snapshot;
 255
 256         return scan;
 257 }
 258
 259 /*
 260  * index_beginscan_internal --- common code for index_beginscan variants
 261  */
 262 static IndexScanDesc
 263 index_beginscan_internal(Relation indexRelation,
 264                                                  int nkeys, ScanKey key)
 265 {
 266         IndexScanDesc scan;
 267         FmgrInfo   *procedure;
 268
 269         RELATION_CHECKS;
 270         GET_REL_PROCEDURE(ambeginscan);
 271
 272         /*
 273          * We hold a reference count to the relcache entry throughout the scan.
 274          */
 275         RelationIncrementReferenceCount(indexRelation);
 276
 277         /*
 278          * Tell the AM to open a scan.
 279          */
 280         scan = (IndexScanDesc)
 281                 DatumGetPointer(FunctionCall3(procedure,
 282                                                                           PointerGetDatum(indexRelation),
 283                                                                           Int32GetDatum(nkeys),
 284                                                                           PointerGetDatum(key)));
 285
 286         return scan;
 287 }
 288
 289 /* ----------------
 290  *              index_rescan  - (re)start a scan of an index
 291  *
 292  * The caller may specify a new set of scankeys (but the number of keys
 293  * cannot change).      To restart the scan without changing keys, pass NULL
 294  * for the key array.
 295  *
 296  * Note that this is also called when first starting an indexscan;
 297  * see RelationGetIndexScan.  Keys *must* be passed in that case,
 298  * unless scan->numberOfKeys is zero.
 299  * ----------------
 300  */
 301 void
 302 index_rescan(IndexScanDesc scan, ScanKey key)
 303 {
 304         FmgrInfo   *procedure;
 305
 306         SCAN_CHECKS;
 307         GET_SCAN_PROCEDURE(amrescan);
 308
 309         /* Release any held pin on a heap page */
 310         if (BufferIsValid(scan->xs_cbuf))
 311         {
 312                 ReleaseBuffer(scan->xs_cbuf);
 313                 scan->xs_cbuf = InvalidBuffer;
 314         }
 315
 316         scan->kill_prior_tuple = false;         /* for safety */
 317
 318         FunctionCall2(procedure,
 319                                   PointerGetDatum(scan),
 320                                   PointerGetDatum(key));
 321 }
 322
 323 /* ----------------
 324  *              index_endscan - end a scan
 325  * ----------------
 326  */
 327 void
 328 index_endscan(IndexScanDesc scan)
 329 {
 330         FmgrInfo   *procedure;
 331
 332         SCAN_CHECKS;
 333         GET_SCAN_PROCEDURE(amendscan);
 334
 335         /* Release any held pin on a heap page */
 336         if (BufferIsValid(scan->xs_cbuf))
 337         {
 338                 ReleaseBuffer(scan->xs_cbuf);
 339                 scan->xs_cbuf = InvalidBuffer;
 340         }
 341
 342         /* End the AM's scan */
 343         FunctionCall1(procedure, PointerGetDatum(scan));
 344
 345         /* Release index refcount acquired by index_beginscan */
 346         RelationDecrementReferenceCount(scan->indexRelation);
 347
 348         /* Release the scan data structure itself */
 349         IndexScanEnd(scan);
 350 }
 351
 352 /* ----------------
 353  *              index_markpos  - mark a scan position
 354  * ----------------
 355  */
 356 void
 357 index_markpos(IndexScanDesc scan)
 358 {
 359         FmgrInfo   *procedure;
 360
 361         SCAN_CHECKS;
 362         GET_SCAN_PROCEDURE(ammarkpos);
 363
 364         FunctionCall1(procedure, PointerGetDatum(scan));
 365 }
 366
 367 /* ----------------
 368  *              index_restrpos  - restore a scan position
 369  *
 370  * NOTE: this only restores the internal scan state of the index AM.
 371  * The current result tuple (scan->xs_ctup) doesn't change.  See comments
 372  * for ExecRestrPos().
 373  * ----------------
 374  */
 375 void
 376 index_restrpos(IndexScanDesc scan)
 377 {
 378         FmgrInfo   *procedure;
 379
 380         SCAN_CHECKS;
 381         GET_SCAN_PROCEDURE(amrestrpos);
 382
 383         scan->kill_prior_tuple = false;         /* for safety */
 384
 385         FunctionCall1(procedure, PointerGetDatum(scan));
 386 }
 387
 388 /* ----------------
 389  *              index_getnext - get the next heap tuple from a scan
 390  *
 391  * The result is the next heap tuple satisfying the scan keys and the
 392  * snapshot, or NULL if no more matching tuples exist.  On success,
 393  * the buffer containing the heap tuple is pinned (the pin will be dropped
 394  * at the next index_getnext or index_endscan).
 395  * ----------------
 396  */
 397 HeapTuple
 398 index_getnext(IndexScanDesc scan, ScanDirection direction)
 399 {
 400         HeapTuple       heapTuple = &scan->xs_ctup;
 401         FmgrInfo   *procedure;
 402
 403         SCAN_CHECKS;
 404         GET_SCAN_PROCEDURE(amgettuple);
 405
 406         /* just make sure this is false... */
 407         scan->kill_prior_tuple = false;
 408
 409         for (;;)
 410         {
 411                 bool            found;
 412
 413                 /*
 414                  * The AM's gettuple proc finds the next tuple matching the scan keys.
 415                  */
 416                 found = DatumGetBool(FunctionCall2(procedure,
 417                                                                                    PointerGetDatum(scan),
 418                                                                                    Int32GetDatum(direction)));
 419
 420                 /* Reset kill flag immediately for safety */
 421                 scan->kill_prior_tuple = false;
 422
 423                 if (!found)
 424                 {
 425                         /* Release any held pin on a heap page */
 426                         if (BufferIsValid(scan->xs_cbuf))
 427                         {
 428                                 ReleaseBuffer(scan->xs_cbuf);
 429                                 scan->xs_cbuf = InvalidBuffer;
 430                         }
 431                         return NULL;            /* failure exit */
 432                 }
 433
 434                 pgstat_count_index_tuples(scan->indexRelation, 1);
 435
 436                 /*
 437                  * Fetch the heap tuple and see if it matches the snapshot.
 438                  */
 439                 if (heap_release_fetch(scan->heapRelation, scan->xs_snapshot,
 440                                                            heapTuple, &scan->xs_cbuf, true,
 441                                                            scan->indexRelation))
 442                         break;
 443
 444                 /* Skip if no undeleted tuple at this location */
 445                 if (heapTuple->t_data == NULL)
 446                         continue;
 447
 448                 /*
 449                  * If we can't see it, maybe no one else can either.  Check to see if
 450                  * the tuple is dead to all transactions.  If so, signal the index AM
 451                  * to not return it on future indexscans.
 452                  *
 453                  * We told heap_release_fetch to keep a pin on the buffer, so we can
 454                  * re-access the tuple here.  But we must re-lock the buffer first.
 455                  */
 456                 LockBuffer(scan->xs_cbuf, BUFFER_LOCK_SHARE);
 457
 458                 if (HeapTupleSatisfiesVacuum(heapTuple->t_data, RecentGlobalXmin,
 459                                                                          scan->xs_cbuf) == HEAPTUPLE_DEAD)
 460                         scan->kill_prior_tuple = true;
 461
 462                 LockBuffer(scan->xs_cbuf, BUFFER_LOCK_UNLOCK);
 463         }
 464
 465         /* Success exit */
 466         return heapTuple;
 467 }
 468
 469 /* ----------------
 470  *              index_getnext_indexitem - get the next index tuple from a scan
 471  *
 472  * Finds the next index tuple satisfying the scan keys.  Note that the
 473  * corresponding heap tuple is not accessed, and thus no time qual (snapshot)
 474  * check is done, other than the index AM's internal check for killed tuples
 475  * (which most callers of this routine will probably want to suppress by
 476  * setting scan->ignore_killed_tuples = false).
 477  *
 478  * On success (TRUE return), the heap TID of the found index entry is in
 479  * scan->xs_ctup.t_self.  scan->xs_cbuf is untouched.
 480  * ----------------
 481  */
 482 bool
 483 index_getnext_indexitem(IndexScanDesc scan,
 484                                                 ScanDirection direction)
 485 {
 486         FmgrInfo   *procedure;
 487         bool            found;
 488
 489         SCAN_CHECKS;
 490         GET_SCAN_PROCEDURE(amgettuple);
 491
 492         /* just make sure this is false... */
 493         scan->kill_prior_tuple = false;
 494
 495         /*
 496          * have the am's gettuple proc do all the work.
 497          */
 498         found = DatumGetBool(FunctionCall2(procedure,
 499                                                                            PointerGetDatum(scan),
 500                                                                            Int32GetDatum(direction)));
 501
 502         if (found)
 503                 pgstat_count_index_tuples(scan->indexRelation, 1);
 504
 505         return found;
 506 }
 507
 508 /* ----------------
 509  *              index_getmulti - get multiple tuples from an index scan
 510  *
 511  * Collects the TIDs of multiple heap tuples satisfying the scan keys.
 512  * Since there's no interlock between the index scan and the eventual heap
 513  * access, this is only safe to use with MVCC-based snapshots: the heap
 514  * item slot could have been replaced by a newer tuple by the time we get
 515  * to it.
 516  *
 517  * A TRUE result indicates more calls should occur; a FALSE result says the
 518  * scan is done.  *returned_tids could be zero or nonzero in either case.
 519  * ----------------
 520  */
 521 bool
 522 index_getmulti(IndexScanDesc scan,
 523                            ItemPointer tids, int32 max_tids,
 524                            int32 *returned_tids)
 525 {
 526         FmgrInfo   *procedure;
 527         bool            found;
 528
 529         SCAN_CHECKS;
 530         GET_SCAN_PROCEDURE(amgetmulti);
 531
 532         /* just make sure this is false... */
 533         scan->kill_prior_tuple = false;
 534
 535         /*
 536          * have the am's getmulti proc do all the work.
 537          */
 538         found = DatumGetBool(FunctionCall4(procedure,
 539                                                                            PointerGetDatum(scan),
 540                                                                            PointerGetDatum(tids),
 541                                                                            Int32GetDatum(max_tids),
 542                                                                            PointerGetDatum(returned_tids)));
 543
 544         pgstat_count_index_tuples(scan->indexRelation, *returned_tids);
 545
 546         return found;
 547 }
 548
 549 /* ----------------
 550  *              index_bulk_delete - do mass deletion of index entries
 551  *
 552  *              callback routine tells whether a given main-heap tuple is
 553  *              to be deleted
 554  *
 555  *              return value is an optional palloc'd struct of statistics
 556  * ----------------
 557  */
 558 IndexBulkDeleteResult *
 559 index_bulk_delete(IndexVacuumInfo *info,
 560                                   IndexBulkDeleteResult *stats,
 561                                   IndexBulkDeleteCallback callback,
 562                                   void *callback_state)
 563 {
 564         Relation        indexRelation = info->index;
 565         FmgrInfo   *procedure;
 566         IndexBulkDeleteResult *result;
 567
 568         RELATION_CHECKS;
 569         GET_REL_PROCEDURE(ambulkdelete);
 570
 571         result = (IndexBulkDeleteResult *)
 572                 DatumGetPointer(FunctionCall4(procedure,
 573                                                                           PointerGetDatum(info),
 574                                                                           PointerGetDatum(stats),
 575                                                                           PointerGetDatum((Pointer) callback),
 576                                                                           PointerGetDatum(callback_state)));
 577
 578         return result;
 579 }
 580
 581 /* ----------------
 582  *              index_vacuum_cleanup - do post-deletion cleanup of an index
 583  *
 584  *              return value is an optional palloc'd struct of statistics
 585  * ----------------
 586  */
 587 IndexBulkDeleteResult *
 588 index_vacuum_cleanup(IndexVacuumInfo *info,
 589                                          IndexBulkDeleteResult *stats)
 590 {
 591         Relation        indexRelation = info->index;
 592         FmgrInfo   *procedure;
 593         IndexBulkDeleteResult *result;
 594
 595         RELATION_CHECKS;
 596         GET_REL_PROCEDURE(amvacuumcleanup);
 597
 598         result = (IndexBulkDeleteResult *)
 599                 DatumGetPointer(FunctionCall2(procedure,
 600                                                                           PointerGetDatum(info),
 601                                                                           PointerGetDatum(stats)));
 602
 603         return result;
 604 }
 605
 606 /* ----------------
 607  *              index_getprocid
 608  *
 609  *              Index access methods typically require support routines that are
 610  *              not directly the implementation of any WHERE-clause query operator
 611  *              and so cannot be kept in pg_amop.  Instead, such routines are kept
 612  *              in pg_amproc.  These registered procedure OIDs are assigned numbers
 613  *              according to a convention established by the access method.
 614  *              The general index code doesn't know anything about the routines
 615  *              involved; it just builds an ordered list of them for
 616  *              each attribute on which an index is defined.
 617  *
 618  *              As of Postgres 8.3, support routines within an operator family
 619  *              are further subdivided by the "left type" and "right type" of the
 620  *              query operator(s) that they support.  The "default" functions for a
 621  *              particular indexed attribute are those with both types equal to
 622  *              the index opclass' opcintype (note that this is subtly different
 623  *              from the indexed attribute's own type: it may be a binary-compatible
 624  *              type instead).  Only the default functions are stored in relcache
 625  *              entries --- access methods can use the syscache to look up non-default
 626  *              functions.
 627  *
 628  *              This routine returns the requested default procedure OID for a
 629  *              particular indexed attribute.
 630  * ----------------
 631  */
 632 RegProcedure
 633 index_getprocid(Relation irel,
 634                                 AttrNumber attnum,
 635                                 uint16 procnum)
 636 {
 637         RegProcedure *loc;
 638         int                     nproc;
 639         int                     procindex;
 640
 641         nproc = irel->rd_am->amsupport;
 642
 643         Assert(procnum > 0 && procnum <= (uint16) nproc);
 644
 645         procindex = (nproc * (attnum - 1)) + (procnum - 1);
 646
 647         loc = irel->rd_support;
 648
 649         Assert(loc != NULL);
 650
 651         return loc[procindex];
 652 }
 653
 654 /* ----------------
 655  *              index_getprocinfo
 656  *
 657  *              This routine allows index AMs to keep fmgr lookup info for
 658  *              support procs in the relcache.  As above, only the "default"
 659  *              functions for any particular indexed attribute are cached.
 660  *
 661  * Note: the return value points into cached data that will be lost during
 662  * any relcache rebuild!  Therefore, either use the callinfo right away,
 663  * or save it only after having acquired some type of lock on the index rel.
 664  * ----------------
 665  */
 666 FmgrInfo *
 667 index_getprocinfo(Relation irel,
 668                                   AttrNumber attnum,
 669                                   uint16 procnum)
 670 {
 671         FmgrInfo   *locinfo;
 672         int                     nproc;
 673         int                     procindex;
 674
 675         nproc = irel->rd_am->amsupport;
 676
 677         Assert(procnum > 0 && procnum <= (uint16) nproc);
 678
 679         procindex = (nproc * (attnum - 1)) + (procnum - 1);
 680
 681         locinfo = irel->rd_supportinfo;
 682
 683         Assert(locinfo != NULL);
 684
 685         locinfo += procindex;
 686
 687         /* Initialize the lookup info if first time through */
 688         if (locinfo->fn_oid == InvalidOid)
 689         {
 690                 RegProcedure *loc = irel->rd_support;
 691                 RegProcedure procId;
 692
 693                 Assert(loc != NULL);
 694
 695                 procId = loc[procindex];
 696
 697                 /*
 698                  * Complain if function was not found during IndexSupportInitialize.
 699                  * This should not happen unless the system tables contain bogus
 700                  * entries for the index opclass.  (If an AM wants to allow a support
 701                  * function to be optional, it can use index_getprocid.)
 702                  */
 703                 if (!RegProcedureIsValid(procId))
 704                         elog(ERROR, "missing support function %d for attribute %d of index \"%s\"",
 705                                  procnum, attnum, RelationGetRelationName(irel));
 706
 707                 fmgr_info_cxt(procId, locinfo, irel->rd_indexcxt);
 708         }
 709
 710         return locinfo;
 711 }