1 /*-------------------------------------------------------------------------
2 *
3 * indexam.c
4 * general index access method routines
5 *
6 * Portions Copyright (c) 1996-2016, 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/amapi.h"
69 #include "access/relscan.h"
70 #include "access/transam.h"
71 #include "access/xlog.h"
72 #include "catalog/catalog.h"
73 #include "catalog/index.h"
74 #include "pgstat.h"
75 #include "storage/bufmgr.h"
76 #include "storage/lmgr.h"
77 #include "storage/predicate.h"
78 #include "utils/snapmgr.h"
79 #include "utils/tqual.h"
80
81
82 /* ----------------------------------------------------------------
83 * macros used in index_ routines
84 *
85 * Note: the ReindexIsProcessingIndex() check in RELATION_CHECKS is there
86 * to check that we don't try to scan or do retail insertions into an index
87 * that is currently being rebuilt or pending rebuild. This helps to catch
88 * things that don't work when reindexing system catalogs. The assertion
89 * doesn't prevent the actual rebuild because we don't use RELATION_CHECKS
90 * when calling the index AM's ambuild routine, and there is no reason for
91 * ambuild to call its subsidiary routines through this file.
92 * ----------------------------------------------------------------
93 */
94 #define RELATION_CHECKS \
95 ( \
96 AssertMacro(RelationIsValid(indexRelation)), \
97 AssertMacro(PointerIsValid(indexRelation->rd_amroutine)), \
98 AssertMacro(!ReindexIsProcessingIndex(RelationGetRelid(indexRelation))) \
99 )
100
101 #define SCAN_CHECKS \
102 ( \
103 AssertMacro(IndexScanIsValid(scan)), \
104 AssertMacro(RelationIsValid(scan->indexRelation)), \
105 AssertMacro(PointerIsValid(scan->indexRelation->rd_amroutine)) \
106 )
107
108 #define CHECK_REL_PROCEDURE(pname) \
109 do { \
110 if (indexRelation->rd_amroutine->pname == NULL) \
111 elog(ERROR, "function %s is not defined for index %s", \
112 CppAsString(pname), RelationGetRelationName(indexRelation)); \
113 } while(0)
114
115 #define CHECK_SCAN_PROCEDURE(pname) \
116 do { \
117 if (scan->indexRelation->rd_amroutine->pname == NULL) \
118 elog(ERROR, "function %s is not defined for index %s", \
119 CppAsString(pname), RelationGetRelationName(scan->indexRelation)); \
120 } while(0)
121
122 static IndexScanDesc index_beginscan_internal(Relation indexRelation,
123 int nkeys, int norderbys, Snapshot snapshot);
124
125
126 /* ----------------------------------------------------------------
127 * index_ interface functions
128 * ----------------------------------------------------------------
129 */
130
131 /* ----------------
132 * index_open - open an index relation by relation OID
133 *
134 * If lockmode is not "NoLock", the specified kind of lock is
135 * obtained on the index. (Generally, NoLock should only be
136 * used if the caller knows it has some appropriate lock on the
137 * index already.)
138 *
139 * An error is raised if the index does not exist.
140 *
141 * This is a convenience routine adapted for indexscan use.
142 * Some callers may prefer to use relation_open directly.
143 * ----------------
144 */
145 Relation
index_open(Oid relationId,LOCKMODE lockmode)146 index_open(Oid relationId, LOCKMODE lockmode)
147 {
148 Relation r;
149
150 r = relation_open(relationId, lockmode);
151
152 if (r->rd_rel->relkind != RELKIND_INDEX)
153 ereport(ERROR,
154 (errcode(ERRCODE_WRONG_OBJECT_TYPE),
155 errmsg("\"%s\" is not an index",
156 RelationGetRelationName(r))));
157
158 return r;
159 }
160
161 /* ----------------
162 * index_close - close an index relation
163 *
164 * If lockmode is not "NoLock", we then release the specified lock.
165 *
166 * Note that it is often sensible to hold a lock beyond index_close;
167 * in that case, the lock is released automatically at xact end.
168 * ----------------
169 */
170 void
index_close(Relation relation,LOCKMODE lockmode)171 index_close(Relation relation, LOCKMODE lockmode)
172 {
173 LockRelId relid = relation->rd_lockInfo.lockRelId;
174
175 Assert(lockmode >= NoLock && lockmode < MAX_LOCKMODES);
176
177 /* The relcache does the real work... */
178 RelationClose(relation);
179
180 if (lockmode != NoLock)
181 UnlockRelationId(&relid, lockmode);
182 }
183
184 /* ----------------
185 * index_insert - insert an index tuple into a relation
186 * ----------------
187 */
188 bool
index_insert(Relation indexRelation,Datum * values,bool * isnull,ItemPointer heap_t_ctid,Relation heapRelation,IndexUniqueCheck checkUnique)189 index_insert(Relation indexRelation,
190 Datum *values,
191 bool *isnull,
192 ItemPointer heap_t_ctid,
193 Relation heapRelation,
194 IndexUniqueCheck checkUnique)
195 {
196 RELATION_CHECKS;
197 CHECK_REL_PROCEDURE(aminsert);
198
199 if (!(indexRelation->rd_amroutine->ampredlocks))
200 CheckForSerializableConflictIn(indexRelation,
201 (HeapTuple) NULL,
202 InvalidBuffer);
203
204 return indexRelation->rd_amroutine->aminsert(indexRelation, values, isnull,
205 heap_t_ctid, heapRelation,
206 checkUnique);
207 }
208
209 /*
210 * index_beginscan - start a scan of an index with amgettuple
211 *
212 * Caller must be holding suitable locks on the heap and the index.
213 */
214 IndexScanDesc
index_beginscan(Relation heapRelation,Relation indexRelation,Snapshot snapshot,int nkeys,int norderbys)215 index_beginscan(Relation heapRelation,
216 Relation indexRelation,
217 Snapshot snapshot,
218 int nkeys, int norderbys)
219 {
220 IndexScanDesc scan;
221
222 scan = index_beginscan_internal(indexRelation, nkeys, norderbys, snapshot);
223
224 /*
225 * Save additional parameters into the scandesc. Everything else was set
226 * up by RelationGetIndexScan.
227 */
228 scan->heapRelation = heapRelation;
229 scan->xs_snapshot = snapshot;
230
231 return scan;
232 }
233
234 /*
235 * index_beginscan_bitmap - start a scan of an index with amgetbitmap
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
index_beginscan_bitmap(Relation indexRelation,Snapshot snapshot,int nkeys)241 index_beginscan_bitmap(Relation indexRelation,
242 Snapshot snapshot,
243 int nkeys)
244 {
245 IndexScanDesc scan;
246
247 scan = index_beginscan_internal(indexRelation, nkeys, 0, snapshot);
248
249 /*
250 * Save additional parameters into the scandesc. Everything else was set
251 * up by RelationGetIndexScan.
252 */
253 scan->xs_snapshot = snapshot;
254
255 return scan;
256 }
257
258 /*
259 * index_beginscan_internal --- common code for index_beginscan variants
260 */
261 static IndexScanDesc
index_beginscan_internal(Relation indexRelation,int nkeys,int norderbys,Snapshot snapshot)262 index_beginscan_internal(Relation indexRelation,
263 int nkeys, int norderbys, Snapshot snapshot)
264 {
265 RELATION_CHECKS;
266 CHECK_REL_PROCEDURE(ambeginscan);
267
268 if (!(indexRelation->rd_amroutine->ampredlocks))
269 PredicateLockRelation(indexRelation, snapshot);
270
271 /*
272 * We hold a reference count to the relcache entry throughout the scan.
273 */
274 RelationIncrementReferenceCount(indexRelation);
275
276 /*
277 * Tell the AM to open a scan.
278 */
279 return indexRelation->rd_amroutine->ambeginscan(indexRelation, nkeys,
280 norderbys);
281 }
282
283 /* ----------------
284 * index_rescan - (re)start a scan of an index
285 *
286 * During a restart, the caller may specify a new set of scankeys and/or
287 * orderbykeys; but the number of keys cannot differ from what index_beginscan
288 * was told. (Later we might relax that to "must not exceed", but currently
289 * the index AMs tend to assume that scan->numberOfKeys is what to believe.)
290 * To restart the scan without changing keys, pass NULL for the key arrays.
291 * (Of course, keys *must* be passed on the first call, unless
292 * scan->numberOfKeys is zero.)
293 * ----------------
294 */
295 void
index_rescan(IndexScanDesc scan,ScanKey keys,int nkeys,ScanKey orderbys,int norderbys)296 index_rescan(IndexScanDesc scan,
297 ScanKey keys, int nkeys,
298 ScanKey orderbys, int norderbys)
299 {
300 SCAN_CHECKS;
301 CHECK_SCAN_PROCEDURE(amrescan);
302
303 Assert(nkeys == scan->numberOfKeys);
304 Assert(norderbys == scan->numberOfOrderBys);
305
306 /* Release any held pin on a heap page */
307 if (BufferIsValid(scan->xs_cbuf))
308 {
309 ReleaseBuffer(scan->xs_cbuf);
310 scan->xs_cbuf = InvalidBuffer;
311 }
312
313 scan->xs_continue_hot = false;
314
315 scan->kill_prior_tuple = false; /* for safety */
316
317 scan->indexRelation->rd_amroutine->amrescan(scan, keys, nkeys,
318 orderbys, norderbys);
319 }
320
321 /* ----------------
322 * index_endscan - end a scan
323 * ----------------
324 */
325 void
index_endscan(IndexScanDesc scan)326 index_endscan(IndexScanDesc scan)
327 {
328 SCAN_CHECKS;
329 CHECK_SCAN_PROCEDURE(amendscan);
330
331 /* Release any held pin on a heap page */
332 if (BufferIsValid(scan->xs_cbuf))
333 {
334 ReleaseBuffer(scan->xs_cbuf);
335 scan->xs_cbuf = InvalidBuffer;
336 }
337
338 /* End the AM's scan */
339 scan->indexRelation->rd_amroutine->amendscan(scan);
340
341 /* Release index refcount acquired by index_beginscan */
342 RelationDecrementReferenceCount(scan->indexRelation);
343
344 /* Release the scan data structure itself */
345 IndexScanEnd(scan);
346 }
347
348 /* ----------------
349 * index_markpos - mark a scan position
350 * ----------------
351 */
352 void
index_markpos(IndexScanDesc scan)353 index_markpos(IndexScanDesc scan)
354 {
355 SCAN_CHECKS;
356 CHECK_SCAN_PROCEDURE(ammarkpos);
357
358 scan->indexRelation->rd_amroutine->ammarkpos(scan);
359 }
360
361 /* ----------------
362 * index_restrpos - restore a scan position
363 *
364 * NOTE: this only restores the internal scan state of the index AM.
365 * The current result tuple (scan->xs_ctup) doesn't change. See comments
366 * for ExecRestrPos().
367 *
368 * NOTE: in the presence of HOT chains, mark/restore only works correctly
369 * if the scan's snapshot is MVCC-safe; that ensures that there's at most one
370 * returnable tuple in each HOT chain, and so restoring the prior state at the
371 * granularity of the index AM is sufficient. Since the only current user
372 * of mark/restore functionality is nodeMergejoin.c, this effectively means
373 * that merge-join plans only work for MVCC snapshots. This could be fixed
374 * if necessary, but for now it seems unimportant.
375 * ----------------
376 */
377 void
index_restrpos(IndexScanDesc scan)378 index_restrpos(IndexScanDesc scan)
379 {
380 Assert(IsMVCCSnapshot(scan->xs_snapshot));
381
382 SCAN_CHECKS;
383 CHECK_SCAN_PROCEDURE(amrestrpos);
384
385 scan->xs_continue_hot = false;
386
387 scan->kill_prior_tuple = false; /* for safety */
388
389 scan->indexRelation->rd_amroutine->amrestrpos(scan);
390 }
391
392 /* ----------------
393 * index_getnext_tid - get the next TID from a scan
394 *
395 * The result is the next TID satisfying the scan keys,
396 * or NULL if no more matching tuples exist.
397 * ----------------
398 */
399 ItemPointer
index_getnext_tid(IndexScanDesc scan,ScanDirection direction)400 index_getnext_tid(IndexScanDesc scan, ScanDirection direction)
401 {
402 bool found;
403
404 SCAN_CHECKS;
405 CHECK_SCAN_PROCEDURE(amgettuple);
406
407 Assert(TransactionIdIsValid(RecentGlobalXmin));
408
409 /*
410 * The AM's amgettuple proc finds the next index entry matching the scan
411 * keys, and puts the TID into scan->xs_ctup.t_self. It should also set
412 * scan->xs_recheck and possibly scan->xs_itup, though we pay no attention
413 * to those fields here.
414 */
415 found = scan->indexRelation->rd_amroutine->amgettuple(scan, direction);
416
417 /* Reset kill flag immediately for safety */
418 scan->kill_prior_tuple = false;
419
420 /* If we're out of index entries, we're done */
421 if (!found)
422 {
423 /* ... but first, release any held pin on a heap page */
424 if (BufferIsValid(scan->xs_cbuf))
425 {
426 ReleaseBuffer(scan->xs_cbuf);
427 scan->xs_cbuf = InvalidBuffer;
428 }
429 return NULL;
430 }
431
432 pgstat_count_index_tuples(scan->indexRelation, 1);
433
434 /* Return the TID of the tuple we found. */
435 return &scan->xs_ctup.t_self;
436 }
437
438 /* ----------------
439 * index_fetch_heap - get the scan's next heap tuple
440 *
441 * The result is a visible heap tuple associated with the index TID most
442 * recently fetched by index_getnext_tid, or NULL if no more matching tuples
443 * exist. (There can be more than one matching tuple because of HOT chains,
444 * although when using an MVCC snapshot it should be impossible for more than
445 * one such tuple to exist.)
446 *
447 * On success, the buffer containing the heap tup is pinned (the pin will be
448 * dropped in a future index_getnext_tid, index_fetch_heap or index_endscan
449 * call).
450 *
451 * Note: caller must check scan->xs_recheck, and perform rechecking of the
452 * scan keys if required. We do not do that here because we don't have
453 * enough information to do it efficiently in the general case.
454 * ----------------
455 */
456 HeapTuple
index_fetch_heap(IndexScanDesc scan)457 index_fetch_heap(IndexScanDesc scan)
458 {
459 ItemPointer tid = &scan->xs_ctup.t_self;
460 bool all_dead = false;
461 bool got_heap_tuple;
462
463 /* We can skip the buffer-switching logic if we're in mid-HOT chain. */
464 if (!scan->xs_continue_hot)
465 {
466 /* Switch to correct buffer if we don't have it already */
467 Buffer prev_buf = scan->xs_cbuf;
468
469 scan->xs_cbuf = ReleaseAndReadBuffer(scan->xs_cbuf,
470 scan->heapRelation,
471 ItemPointerGetBlockNumber(tid));
472
473 /*
474 * Prune page, but only if we weren't already on this page
475 */
476 if (prev_buf != scan->xs_cbuf)
477 heap_page_prune_opt(scan->heapRelation, scan->xs_cbuf);
478 }
479
480 /* Obtain share-lock on the buffer so we can examine visibility */
481 LockBuffer(scan->xs_cbuf, BUFFER_LOCK_SHARE);
482 got_heap_tuple = heap_hot_search_buffer(tid, scan->heapRelation,
483 scan->xs_cbuf,
484 scan->xs_snapshot,
485 &scan->xs_ctup,
486 &all_dead,
487 !scan->xs_continue_hot);
488 LockBuffer(scan->xs_cbuf, BUFFER_LOCK_UNLOCK);
489
490 if (got_heap_tuple)
491 {
492 /*
493 * Only in a non-MVCC snapshot can more than one member of the HOT
494 * chain be visible.
495 */
496 scan->xs_continue_hot = !IsMVCCSnapshot(scan->xs_snapshot);
497 pgstat_count_heap_fetch(scan->indexRelation);
498 return &scan->xs_ctup;
499 }
500
501 /* We've reached the end of the HOT chain. */
502 scan->xs_continue_hot = false;
503
504 /*
505 * If we scanned a whole HOT chain and found only dead tuples, tell index
506 * AM to kill its entry for that TID (this will take effect in the next
507 * amgettuple call, in index_getnext_tid). We do not do this when in
508 * recovery because it may violate MVCC to do so. See comments in
509 * RelationGetIndexScan().
510 */
511 if (!scan->xactStartedInRecovery)
512 scan->kill_prior_tuple = all_dead;
513
514 return NULL;
515 }
516
517 /* ----------------
518 * index_getnext - get the next heap tuple from a scan
519 *
520 * The result is the next heap tuple satisfying the scan keys and the
521 * snapshot, or NULL if no more matching tuples exist.
522 *
523 * On success, the buffer containing the heap tup is pinned (the pin will be
524 * dropped in a future index_getnext_tid, index_fetch_heap or index_endscan
525 * call).
526 *
527 * Note: caller must check scan->xs_recheck, and perform rechecking of the
528 * scan keys if required. We do not do that here because we don't have
529 * enough information to do it efficiently in the general case.
530 * ----------------
531 */
532 HeapTuple
index_getnext(IndexScanDesc scan,ScanDirection direction)533 index_getnext(IndexScanDesc scan, ScanDirection direction)
534 {
535 HeapTuple heapTuple;
536 ItemPointer tid;
537
538 for (;;)
539 {
540 if (scan->xs_continue_hot)
541 {
542 /*
543 * We are resuming scan of a HOT chain after having returned an
544 * earlier member. Must still hold pin on current heap page.
545 */
546 Assert(BufferIsValid(scan->xs_cbuf));
547 Assert(ItemPointerGetBlockNumber(&scan->xs_ctup.t_self) ==
548 BufferGetBlockNumber(scan->xs_cbuf));
549 }
550 else
551 {
552 /* Time to fetch the next TID from the index */
553 tid = index_getnext_tid(scan, direction);
554
555 /* If we're out of index entries, we're done */
556 if (tid == NULL)
557 break;
558 }
559
560 /*
561 * Fetch the next (or only) visible heap tuple for this index entry.
562 * If we don't find anything, loop around and grab the next TID from
563 * the index.
564 */
565 heapTuple = index_fetch_heap(scan);
566 if (heapTuple != NULL)
567 return heapTuple;
568 }
569
570 return NULL; /* failure exit */
571 }
572
573 /* ----------------
574 * index_getbitmap - get all tuples at once from an index scan
575 *
576 * Adds the TIDs of all heap tuples satisfying the scan keys to a bitmap.
577 * Since there's no interlock between the index scan and the eventual heap
578 * access, this is only safe to use with MVCC-based snapshots: the heap
579 * item slot could have been replaced by a newer tuple by the time we get
580 * to it.
581 *
582 * Returns the number of matching tuples found. (Note: this might be only
583 * approximate, so it should only be used for statistical purposes.)
584 * ----------------
585 */
586 int64
index_getbitmap(IndexScanDesc scan,TIDBitmap * bitmap)587 index_getbitmap(IndexScanDesc scan, TIDBitmap *bitmap)
588 {
589 int64 ntids;
590
591 SCAN_CHECKS;
592 CHECK_SCAN_PROCEDURE(amgetbitmap);
593
594 /* just make sure this is false... */
595 scan->kill_prior_tuple = false;
596
597 /*
598 * have the am's getbitmap proc do all the work.
599 */
600 ntids = scan->indexRelation->rd_amroutine->amgetbitmap(scan, bitmap);
601
602 pgstat_count_index_tuples(scan->indexRelation, ntids);
603
604 return ntids;
605 }
606
607 /* ----------------
608 * index_bulk_delete - do mass deletion of index entries
609 *
610 * callback routine tells whether a given main-heap tuple is
611 * to be deleted
612 *
613 * return value is an optional palloc'd struct of statistics
614 * ----------------
615 */
616 IndexBulkDeleteResult *
index_bulk_delete(IndexVacuumInfo * info,IndexBulkDeleteResult * stats,IndexBulkDeleteCallback callback,void * callback_state)617 index_bulk_delete(IndexVacuumInfo *info,
618 IndexBulkDeleteResult *stats,
619 IndexBulkDeleteCallback callback,
620 void *callback_state)
621 {
622 Relation indexRelation = info->index;
623
624 RELATION_CHECKS;
625 CHECK_REL_PROCEDURE(ambulkdelete);
626
627 return indexRelation->rd_amroutine->ambulkdelete(info, stats,
628 callback, callback_state);
629 }
630
631 /* ----------------
632 * index_vacuum_cleanup - do post-deletion cleanup of an index
633 *
634 * return value is an optional palloc'd struct of statistics
635 * ----------------
636 */
637 IndexBulkDeleteResult *
index_vacuum_cleanup(IndexVacuumInfo * info,IndexBulkDeleteResult * stats)638 index_vacuum_cleanup(IndexVacuumInfo *info,
639 IndexBulkDeleteResult *stats)
640 {
641 Relation indexRelation = info->index;
642
643 RELATION_CHECKS;
644 CHECK_REL_PROCEDURE(amvacuumcleanup);
645
646 return indexRelation->rd_amroutine->amvacuumcleanup(info, stats);
647 }
648
649 /* ----------------
650 * index_can_return
651 *
652 * Does the index access method support index-only scans for the given
653 * column?
654 * ----------------
655 */
656 bool
index_can_return(Relation indexRelation,int attno)657 index_can_return(Relation indexRelation, int attno)
658 {
659 RELATION_CHECKS;
660
661 /* amcanreturn is optional; assume FALSE if not provided by AM */
662 if (indexRelation->rd_amroutine->amcanreturn == NULL)
663 return false;
664
665 return indexRelation->rd_amroutine->amcanreturn(indexRelation, attno);
666 }
667
668 /* ----------------
669 * index_getprocid
670 *
671 * Index access methods typically require support routines that are
672 * not directly the implementation of any WHERE-clause query operator
673 * and so cannot be kept in pg_amop. Instead, such routines are kept
674 * in pg_amproc. These registered procedure OIDs are assigned numbers
675 * according to a convention established by the access method.
676 * The general index code doesn't know anything about the routines
677 * involved; it just builds an ordered list of them for
678 * each attribute on which an index is defined.
679 *
680 * As of Postgres 8.3, support routines within an operator family
681 * are further subdivided by the "left type" and "right type" of the
682 * query operator(s) that they support. The "default" functions for a
683 * particular indexed attribute are those with both types equal to
684 * the index opclass' opcintype (note that this is subtly different
685 * from the indexed attribute's own type: it may be a binary-compatible
686 * type instead). Only the default functions are stored in relcache
687 * entries --- access methods can use the syscache to look up non-default
688 * functions.
689 *
690 * This routine returns the requested default procedure OID for a
691 * particular indexed attribute.
692 * ----------------
693 */
694 RegProcedure
index_getprocid(Relation irel,AttrNumber attnum,uint16 procnum)695 index_getprocid(Relation irel,
696 AttrNumber attnum,
697 uint16 procnum)
698 {
699 RegProcedure *loc;
700 int nproc;
701 int procindex;
702
703 nproc = irel->rd_amroutine->amsupport;
704
705 Assert(procnum > 0 && procnum <= (uint16) nproc);
706
707 procindex = (nproc * (attnum - 1)) + (procnum - 1);
708
709 loc = irel->rd_support;
710
711 Assert(loc != NULL);
712
713 return loc[procindex];
714 }
715
716 /* ----------------
717 * index_getprocinfo
718 *
719 * This routine allows index AMs to keep fmgr lookup info for
720 * support procs in the relcache. As above, only the "default"
721 * functions for any particular indexed attribute are cached.
722 *
723 * Note: the return value points into cached data that will be lost during
724 * any relcache rebuild! Therefore, either use the callinfo right away,
725 * or save it only after having acquired some type of lock on the index rel.
726 * ----------------
727 */
728 FmgrInfo *
index_getprocinfo(Relation irel,AttrNumber attnum,uint16 procnum)729 index_getprocinfo(Relation irel,
730 AttrNumber attnum,
731 uint16 procnum)
732 {
733 FmgrInfo *locinfo;
734 int nproc;
735 int procindex;
736
737 nproc = irel->rd_amroutine->amsupport;
738
739 Assert(procnum > 0 && procnum <= (uint16) nproc);
740
741 procindex = (nproc * (attnum - 1)) + (procnum - 1);
742
743 locinfo = irel->rd_supportinfo;
744
745 Assert(locinfo != NULL);
746
747 locinfo += procindex;
748
749 /* Initialize the lookup info if first time through */
750 if (locinfo->fn_oid == InvalidOid)
751 {
752 RegProcedure *loc = irel->rd_support;
753 RegProcedure procId;
754
755 Assert(loc != NULL);
756
757 procId = loc[procindex];
758
759 /*
760 * Complain if function was not found during IndexSupportInitialize.
761 * This should not happen unless the system tables contain bogus
762 * entries for the index opclass. (If an AM wants to allow a support
763 * function to be optional, it can use index_getprocid.)
764 */
765 if (!RegProcedureIsValid(procId))
766 elog(ERROR, "missing support function %d for attribute %d of index \"%s\"",
767 procnum, attnum, RelationGetRelationName(irel));
768
769 fmgr_info_cxt(procId, locinfo, irel->rd_indexcxt);
770 }
771
772 return locinfo;
773 }
774