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) 1996-2006, 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 1.96 2006/12/23 00:43:08 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         pgstat_initstats(&r->pgstat_info, r);
 149
 150         return r;
 151 }
 152
 153 /* ----------------
 154  *              index_close - close an index relation
 155  *
 156  *              If lockmode is not "NoLock", we then release the specified lock.
 157  *
 158  *              Note that it is often sensible to hold a lock beyond index_close;
 159  *              in that case, the lock is released automatically at xact end.
 160  * ----------------
 161  */
 162 void
 163 index_close(Relation relation, LOCKMODE lockmode)
 164 {
 165         LockRelId       relid = relation->rd_lockInfo.lockRelId;
 166
 167         Assert(lockmode >= NoLock && lockmode < MAX_LOCKMODES);
 168
 169         /* The relcache does the real work... */
 170         RelationClose(relation);
 171
 172         if (lockmode != NoLock)
 173                 UnlockRelationId(&relid, lockmode);
 174 }
 175
 176 /* ----------------
 177  *              index_insert - insert an index tuple into a relation
 178  * ----------------
 179  */
 180 bool
 181 index_insert(Relation indexRelation,
 182                          Datum *values,
 183                          bool *isnull,
 184                          ItemPointer heap_t_ctid,
 185                          Relation heapRelation,
 186                          bool check_uniqueness)
 187 {
 188         FmgrInfo   *procedure;
 189
 190         RELATION_CHECKS;
 191         GET_REL_PROCEDURE(aminsert);
 192
 193         /*
 194          * have the am's insert proc do all the work.
 195          */
 196         return DatumGetBool(FunctionCall6(procedure,
 197                                                                           PointerGetDatum(indexRelation),
 198                                                                           PointerGetDatum(values),
 199                                                                           PointerGetDatum(isnull),
 200                                                                           PointerGetDatum(heap_t_ctid),
 201                                                                           PointerGetDatum(heapRelation),
 202                                                                           BoolGetDatum(check_uniqueness)));
 203 }
 204
 205 /*
 206  * index_beginscan - start a scan of an index with amgettuple
 207  *
 208  * Note: heapRelation may be NULL if there is no intention of calling
 209  * index_getnext on this scan; index_getnext_indexitem will not use the
 210  * heapRelation link (nor the snapshot).  However, the caller had better
 211  * be holding some kind of lock on the heap relation in any case, to ensure
 212  * no one deletes it (or the index) out from under us.  Caller must also
 213  * be holding a lock on the index.
 214  */
 215 IndexScanDesc
 216 index_beginscan(Relation heapRelation,
 217                                 Relation indexRelation,
 218                                 Snapshot snapshot,
 219                                 int nkeys, ScanKey key)
 220 {
 221         IndexScanDesc scan;
 222
 223         scan = index_beginscan_internal(indexRelation, nkeys, key);
 224
 225         /*
 226          * Save additional parameters into the scandesc.  Everything else was set
 227          * up by RelationGetIndexScan.
 228          */
 229         scan->is_multiscan = false;
 230         scan->heapRelation = heapRelation;
 231         scan->xs_snapshot = snapshot;
 232
 233         return scan;
 234 }
 235
 236 /*
 237  * index_beginscan_multi - start a scan of an index with amgetmulti
 238  *
 239  * As above, caller had better be holding some lock on the parent heap
 240  * relation, even though it's not explicitly mentioned here.
 241  */
 242 IndexScanDesc
 243 index_beginscan_multi(Relation indexRelation,
 244                                           Snapshot snapshot,
 245                                           int nkeys, ScanKey key)
 246 {
 247         IndexScanDesc scan;
 248
 249         scan = index_beginscan_internal(indexRelation, nkeys, key);
 250
 251         /*
 252          * Save additional parameters into the scandesc.  Everything else was set
 253          * up by RelationGetIndexScan.
 254          */
 255         scan->is_multiscan = true;
 256         scan->xs_snapshot = snapshot;
 257
 258         return scan;
 259 }
 260
 261 /*
 262  * index_beginscan_internal --- common code for index_beginscan variants
 263  */
 264 static IndexScanDesc
 265 index_beginscan_internal(Relation indexRelation,
 266                                                  int nkeys, ScanKey key)
 267 {
 268         IndexScanDesc scan;
 269         FmgrInfo   *procedure;
 270
 271         RELATION_CHECKS;
 272         GET_REL_PROCEDURE(ambeginscan);
 273
 274         /*
 275          * We hold a reference count to the relcache entry throughout the scan.
 276          */
 277         RelationIncrementReferenceCount(indexRelation);
 278
 279         /*
 280          * Tell the AM to open a scan.
 281          */
 282         scan = (IndexScanDesc)
 283                 DatumGetPointer(FunctionCall3(procedure,
 284                                                                           PointerGetDatum(indexRelation),
 285                                                                           Int32GetDatum(nkeys),
 286                                                                           PointerGetDatum(key)));
 287
 288         return scan;
 289 }
 290
 291 /* ----------------
 292  *              index_rescan  - (re)start a scan of an index
 293  *
 294  * The caller may specify a new set of scankeys (but the number of keys
 295  * cannot change).      To restart the scan without changing keys, pass NULL
 296  * for the key array.
 297  *
 298  * Note that this is also called when first starting an indexscan;
 299  * see RelationGetIndexScan.  Keys *must* be passed in that case,
 300  * unless scan->numberOfKeys is zero.
 301  * ----------------
 302  */
 303 void
 304 index_rescan(IndexScanDesc scan, ScanKey key)
 305 {
 306         FmgrInfo   *procedure;
 307
 308         SCAN_CHECKS;
 309         GET_SCAN_PROCEDURE(amrescan);
 310
 311         /* Release any held pin on a heap page */
 312         if (BufferIsValid(scan->xs_cbuf))
 313         {
 314                 ReleaseBuffer(scan->xs_cbuf);
 315                 scan->xs_cbuf = InvalidBuffer;
 316         }
 317
 318         scan->kill_prior_tuple = false;         /* for safety */
 319
 320         FunctionCall2(procedure,
 321                                   PointerGetDatum(scan),
 322                                   PointerGetDatum(key));
 323 }
 324
 325 /* ----------------
 326  *              index_endscan - end a scan
 327  * ----------------
 328  */
 329 void
 330 index_endscan(IndexScanDesc scan)
 331 {
 332         FmgrInfo   *procedure;
 333
 334         SCAN_CHECKS;
 335         GET_SCAN_PROCEDURE(amendscan);
 336
 337         /* Release any held pin on a heap page */
 338         if (BufferIsValid(scan->xs_cbuf))
 339         {
 340                 ReleaseBuffer(scan->xs_cbuf);
 341                 scan->xs_cbuf = InvalidBuffer;
 342         }
 343
 344         /* End the AM's scan */
 345         FunctionCall1(procedure, PointerGetDatum(scan));
 346
 347         /* Release index refcount acquired by index_beginscan */
 348         RelationDecrementReferenceCount(scan->indexRelation);
 349
 350         /* Release the scan data structure itself */
 351         IndexScanEnd(scan);
 352 }
 353
 354 /* ----------------
 355  *              index_markpos  - mark a scan position
 356  * ----------------
 357  */
 358 void
 359 index_markpos(IndexScanDesc scan)
 360 {
 361         FmgrInfo   *procedure;
 362
 363         SCAN_CHECKS;
 364         GET_SCAN_PROCEDURE(ammarkpos);
 365
 366         FunctionCall1(procedure, PointerGetDatum(scan));
 367 }
 368
 369 /* ----------------
 370  *              index_restrpos  - restore a scan position
 371  *
 372  * NOTE: this only restores the internal scan state of the index AM.
 373  * The current result tuple (scan->xs_ctup) doesn't change.  See comments
 374  * for ExecRestrPos().
 375  * ----------------
 376  */
 377 void
 378 index_restrpos(IndexScanDesc scan)
 379 {
 380         FmgrInfo   *procedure;
 381
 382         SCAN_CHECKS;
 383         GET_SCAN_PROCEDURE(amrestrpos);
 384
 385         scan->kill_prior_tuple = false;         /* for safety */
 386
 387         FunctionCall1(procedure, PointerGetDatum(scan));
 388 }
 389
 390 /* ----------------
 391  *              index_getnext - get the next heap tuple from a scan
 392  *
 393  * The result is the next heap tuple satisfying the scan keys and the
 394  * snapshot, or NULL if no more matching tuples exist.  On success,
 395  * the buffer containing the heap tuple is pinned (the pin will be dropped
 396  * at the next index_getnext or index_endscan).
 397  * ----------------
 398  */
 399 HeapTuple
 400 index_getnext(IndexScanDesc scan, ScanDirection direction)
 401 {
 402         HeapTuple       heapTuple = &scan->xs_ctup;
 403         FmgrInfo   *procedure;
 404
 405         SCAN_CHECKS;
 406         GET_SCAN_PROCEDURE(amgettuple);
 407
 408         /* just make sure this is false... */
 409         scan->kill_prior_tuple = false;
 410
 411         for (;;)
 412         {
 413                 bool            found;
 414
 415                 /*
 416                  * The AM's gettuple proc finds the next tuple matching the scan keys.
 417                  */
 418                 found = DatumGetBool(FunctionCall2(procedure,
 419                                                                                    PointerGetDatum(scan),
 420                                                                                    Int32GetDatum(direction)));
 421
 422                 /* Reset kill flag immediately for safety */
 423                 scan->kill_prior_tuple = false;
 424
 425                 if (!found)
 426                 {
 427                         /* Release any held pin on a heap page */
 428                         if (BufferIsValid(scan->xs_cbuf))
 429                         {
 430                                 ReleaseBuffer(scan->xs_cbuf);
 431                                 scan->xs_cbuf = InvalidBuffer;
 432                         }
 433                         return NULL;            /* failure exit */
 434                 }
 435
 436                 pgstat_count_index_tuples(&scan->xs_pgstat_info, 1);
 437
 438                 /*
 439                  * Fetch the heap tuple and see if it matches the snapshot.
 440                  */
 441                 if (heap_release_fetch(scan->heapRelation, scan->xs_snapshot,
 442                                                            heapTuple, &scan->xs_cbuf, true,
 443                                                            &scan->xs_pgstat_info))
 444                         break;
 445
 446                 /* Skip if no undeleted tuple at this location */
 447                 if (heapTuple->t_data == NULL)
 448                         continue;
 449
 450                 /*
 451                  * If we can't see it, maybe no one else can either.  Check to see if
 452                  * the tuple is dead to all transactions.  If so, signal the index AM
 453                  * to not return it on future indexscans.
 454                  *
 455                  * We told heap_release_fetch to keep a pin on the buffer, so we can
 456                  * re-access the tuple here.  But we must re-lock the buffer first.
 457                  */
 458                 LockBuffer(scan->xs_cbuf, BUFFER_LOCK_SHARE);
 459
 460                 if (HeapTupleSatisfiesVacuum(heapTuple->t_data, RecentGlobalXmin,
 461                                                                          scan->xs_cbuf) == HEAPTUPLE_DEAD)
 462                         scan->kill_prior_tuple = true;
 463
 464                 LockBuffer(scan->xs_cbuf, BUFFER_LOCK_UNLOCK);
 465         }
 466
 467         /* Success exit */
 468         return heapTuple;
 469 }
 470
 471 /* ----------------
 472  *              index_getnext_indexitem - get the next index tuple from a scan
 473  *
 474  * Finds the next index tuple satisfying the scan keys.  Note that the
 475  * corresponding heap tuple is not accessed, and thus no time qual (snapshot)
 476  * check is done, other than the index AM's internal check for killed tuples
 477  * (which most callers of this routine will probably want to suppress by
 478  * setting scan->ignore_killed_tuples = false).
 479  *
 480  * On success (TRUE return), the heap TID of the found index entry is in
 481  * scan->xs_ctup.t_self.  scan->xs_cbuf is untouched.
 482  * ----------------
 483  */
 484 bool
 485 index_getnext_indexitem(IndexScanDesc scan,
 486                                                 ScanDirection direction)
 487 {
 488         FmgrInfo   *procedure;
 489         bool            found;
 490
 491         SCAN_CHECKS;
 492         GET_SCAN_PROCEDURE(amgettuple);
 493
 494         /* just make sure this is false... */
 495         scan->kill_prior_tuple = false;
 496
 497         /*
 498          * have the am's gettuple proc do all the work.
 499          */
 500         found = DatumGetBool(FunctionCall2(procedure,
 501                                                                            PointerGetDatum(scan),
 502                                                                            Int32GetDatum(direction)));
 503
 504         if (found)
 505                 pgstat_count_index_tuples(&scan->xs_pgstat_info, 1);
 506
 507         return found;
 508 }
 509
 510 /* ----------------
 511  *              index_getmulti - get multiple tuples from an index scan
 512  *
 513  * Collects the TIDs of multiple heap tuples satisfying the scan keys.
 514  * Since there's no interlock between the index scan and the eventual heap
 515  * access, this is only safe to use with MVCC-based snapshots: the heap
 516  * item slot could have been replaced by a newer tuple by the time we get
 517  * to it.
 518  *
 519  * A TRUE result indicates more calls should occur; a FALSE result says the
 520  * scan is done.  *returned_tids could be zero or nonzero in either case.
 521  * ----------------
 522  */
 523 bool
 524 index_getmulti(IndexScanDesc scan,
 525                            ItemPointer tids, int32 max_tids,
 526                            int32 *returned_tids)
 527 {
 528         FmgrInfo   *procedure;
 529         bool            found;
 530
 531         SCAN_CHECKS;
 532         GET_SCAN_PROCEDURE(amgetmulti);
 533
 534         /* just make sure this is false... */
 535         scan->kill_prior_tuple = false;
 536
 537         /*
 538          * have the am's getmulti proc do all the work.
 539          */
 540         found = DatumGetBool(FunctionCall4(procedure,
 541                                                                            PointerGetDatum(scan),
 542                                                                            PointerGetDatum(tids),
 543                                                                            Int32GetDatum(max_tids),
 544                                                                            PointerGetDatum(returned_tids)));
 545
 546         pgstat_count_index_tuples(&scan->xs_pgstat_info, *returned_tids);
 547
 548         return found;
 549 }
 550
 551 /* ----------------
 552  *              index_bulk_delete - do mass deletion of index entries
 553  *
 554  *              callback routine tells whether a given main-heap tuple is
 555  *              to be deleted
 556  *
 557  *              return value is an optional palloc'd struct of statistics
 558  * ----------------
 559  */
 560 IndexBulkDeleteResult *
 561 index_bulk_delete(IndexVacuumInfo *info,
 562                                   IndexBulkDeleteResult *stats,
 563                                   IndexBulkDeleteCallback callback,
 564                                   void *callback_state)
 565 {
 566         Relation        indexRelation = info->index;
 567         FmgrInfo   *procedure;
 568         IndexBulkDeleteResult *result;
 569
 570         RELATION_CHECKS;
 571         GET_REL_PROCEDURE(ambulkdelete);
 572
 573         result = (IndexBulkDeleteResult *)
 574                 DatumGetPointer(FunctionCall4(procedure,
 575                                                                           PointerGetDatum(info),
 576                                                                           PointerGetDatum(stats),
 577                                                                           PointerGetDatum((Pointer) callback),
 578                                                                           PointerGetDatum(callback_state)));
 579
 580         return result;
 581 }
 582
 583 /* ----------------
 584  *              index_vacuum_cleanup - do post-deletion cleanup of an index
 585  *
 586  *              return value is an optional palloc'd struct of statistics
 587  * ----------------
 588  */
 589 IndexBulkDeleteResult *
 590 index_vacuum_cleanup(IndexVacuumInfo *info,
 591                                          IndexBulkDeleteResult *stats)
 592 {
 593         Relation        indexRelation = info->index;
 594         FmgrInfo   *procedure;
 595         IndexBulkDeleteResult *result;
 596
 597         RELATION_CHECKS;
 598         GET_REL_PROCEDURE(amvacuumcleanup);
 599
 600         result = (IndexBulkDeleteResult *)
 601                 DatumGetPointer(FunctionCall2(procedure,
 602                                                                           PointerGetDatum(info),
 603                                                                           PointerGetDatum(stats)));
 604
 605         return result;
 606 }
 607
 608 /* ----------------
 609  *              index_getprocid
 610  *
 611  *              Index access methods typically require support routines that are
 612  *              not directly the implementation of any WHERE-clause query operator
 613  *              and so cannot be kept in pg_amop.  Instead, such routines are kept
 614  *              in pg_amproc.  These registered procedure OIDs are assigned numbers
 615  *              according to a convention established by the access method.
 616  *              The general index code doesn't know anything about the routines
 617  *              involved; it just builds an ordered list of them for
 618  *              each attribute on which an index is defined.
 619  *
 620  *              As of Postgres 8.3, support routines within an operator family
 621  *              are further subdivided by the "left type" and "right type" of the
 622  *              query operator(s) that they support.  The "default" functions for a
 623  *              particular indexed attribute are those with both types equal to
 624  *              the index opclass' opcintype (note that this is subtly different
 625  *              from the indexed attribute's own type: it may be a binary-compatible
 626  *              type instead).  Only the default functions are stored in relcache
 627  *              entries --- access methods can use the syscache to look up non-default
 628  *              functions.
 629  *
 630  *              This routine returns the requested default procedure OID for a
 631  *              particular indexed attribute.
 632  * ----------------
 633  */
 634 RegProcedure
 635 index_getprocid(Relation irel,
 636                                 AttrNumber attnum,
 637                                 uint16 procnum)
 638 {
 639         RegProcedure *loc;
 640         int                     nproc;
 641         int                     procindex;
 642
 643         nproc = irel->rd_am->amsupport;
 644
 645         Assert(procnum > 0 && procnum <= (uint16) nproc);
 646
 647         procindex = (nproc * (attnum - 1)) + (procnum - 1);
 648
 649         loc = irel->rd_support;
 650
 651         Assert(loc != NULL);
 652
 653         return loc[procindex];
 654 }
 655
 656 /* ----------------
 657  *              index_getprocinfo
 658  *
 659  *              This routine allows index AMs to keep fmgr lookup info for
 660  *              support procs in the relcache.  As above, only the "default"
 661  *              functions for any particular indexed attribute are cached.
 662  *
 663  * Note: the return value points into cached data that will be lost during
 664  * any relcache rebuild!  Therefore, either use the callinfo right away,
 665  * or save it only after having acquired some type of lock on the index rel.
 666  * ----------------
 667  */
 668 FmgrInfo *
 669 index_getprocinfo(Relation irel,
 670                                   AttrNumber attnum,
 671                                   uint16 procnum)
 672 {
 673         FmgrInfo   *locinfo;
 674         int                     nproc;
 675         int                     procindex;
 676
 677         nproc = irel->rd_am->amsupport;
 678
 679         Assert(procnum > 0 && procnum <= (uint16) nproc);
 680
 681         procindex = (nproc * (attnum - 1)) + (procnum - 1);
 682
 683         locinfo = irel->rd_supportinfo;
 684
 685         Assert(locinfo != NULL);
 686
 687         locinfo += procindex;
 688
 689         /* Initialize the lookup info if first time through */
 690         if (locinfo->fn_oid == InvalidOid)
 691         {
 692                 RegProcedure *loc = irel->rd_support;
 693                 RegProcedure procId;
 694
 695                 Assert(loc != NULL);
 696
 697                 procId = loc[procindex];
 698
 699                 /*
 700                  * Complain if function was not found during IndexSupportInitialize.
 701                  * This should not happen unless the system tables contain bogus
 702                  * entries for the index opclass.  (If an AM wants to allow a support
 703                  * function to be optional, it can use index_getprocid.)
 704                  */
 705                 if (!RegProcedureIsValid(procId))
 706                         elog(ERROR, "missing support function %d for attribute %d of index \"%s\"",
 707                                  procnum, attnum, RelationGetRelationName(irel));
 708
 709                 fmgr_info_cxt(procId, locinfo, irel->rd_indexcxt);
 710         }
 711
 712         return locinfo;
 713 }