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Force a checkpoint in CREATE DATABASE before starting to copy the files,
[PostgreSQL.git] / src / backend / access / index / indexam.c
blob0d101acbe9ddf5da683e01e3d14ce1cfb4c8ac94
1 /*-------------------------------------------------------------------------
2 *
3 * indexam.c
4 * general index access method routines
5 *
6 * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
7 * Portions Copyright (c) 1994, Regents of the University of California
8 *
9 *
10 * IDENTIFICATION
11 * $PostgreSQL$
12 *
13 * INTERFACE ROUTINES
14 * index_open - open an index relation by relation OID
15 * index_close - close an index relation
16 * index_beginscan - start a scan of an index with amgettuple
17 * index_beginscan_bitmap - start a scan of an index with amgetbitmap
18 * index_rescan - restart a scan of an index
19 * index_endscan - end a scan
20 * index_insert - insert an index tuple into a relation
21 * index_markpos - mark a scan position
22 * index_restrpos - restore a scan position
23 * index_getnext - get the next tuple from a scan
24 * index_getbitmap - get all tuples from a scan
25 * index_bulk_delete - bulk deletion of index tuples
26 * index_vacuum_cleanup - post-deletion cleanup of an index
27 * index_getprocid - get a support procedure OID
28 * index_getprocinfo - get a support procedure's lookup info
29 *
30 * NOTES
31 * This file contains the index_ routines which used
32 * to be a scattered collection of stuff in access/genam.
33 *
34 *
35 * old comments
36 * Scans are implemented as follows:
37 *
38 * `0' represents an invalid item pointer.
39 * `-' represents an unknown item pointer.
40 * `X' represents a known item pointers.
41 * `+' represents known or invalid item pointers.
42 * `*' represents any item pointers.
43 *
44 * State is represented by a triple of these symbols in the order of
45 * previous, current, next. Note that the case of reverse scans works
46 * identically.
47 *
48 * State Result
49 * (1) + + - + 0 0 (if the next item pointer is invalid)
50 * (2) + X - (otherwise)
51 * (3) * 0 0 * 0 0 (no change)
52 * (4) + X 0 X 0 0 (shift)
53 * (5) * + X + X - (shift, add unknown)
54 *
55 * All other states cannot occur.
56 *
57 * Note: It would be possible to cache the status of the previous and
58 * next item pointer using the flags.
59 *
60 *-------------------------------------------------------------------------
61 */
62
63 #include "postgres.h"
64
65 #include "access/relscan.h"
66 #include "access/transam.h"
67 #include "pgstat.h"
68 #include "storage/bufmgr.h"
69 #include "storage/lmgr.h"
70 #include "utils/relcache.h"
71 #include "utils/snapmgr.h"
72 #include "utils/tqual.h"
73
74
75 /* ----------------------------------------------------------------
76 * macros used in index_ routines
77 * ----------------------------------------------------------------
78 */
79 #define RELATION_CHECKS \
80 ( \
81 AssertMacro(RelationIsValid(indexRelation)), \
82 AssertMacro(PointerIsValid(indexRelation->rd_am)) \
83 )
84
85 #define SCAN_CHECKS \
86 ( \
87 AssertMacro(IndexScanIsValid(scan)), \
88 AssertMacro(RelationIsValid(scan->indexRelation)), \
89 AssertMacro(PointerIsValid(scan->indexRelation->rd_am)) \
90 )
91
92 #define GET_REL_PROCEDURE(pname) \
93 do { \
94 procedure = &indexRelation->rd_aminfo->pname; \
95 if (!OidIsValid(procedure->fn_oid)) \
96 { \
97 RegProcedure procOid = indexRelation->rd_am->pname; \
98 if (!RegProcedureIsValid(procOid)) \
99 elog(ERROR, "invalid %s regproc", CppAsString(pname)); \
100 fmgr_info_cxt(procOid, procedure, indexRelation->rd_indexcxt); \
101 } \
102 } while(0)
103
104 #define GET_SCAN_PROCEDURE(pname) \
105 do { \
106 procedure = &scan->indexRelation->rd_aminfo->pname; \
107 if (!OidIsValid(procedure->fn_oid)) \
108 { \
109 RegProcedure procOid = scan->indexRelation->rd_am->pname; \
110 if (!RegProcedureIsValid(procOid)) \
111 elog(ERROR, "invalid %s regproc", CppAsString(pname)); \
112 fmgr_info_cxt(procOid, procedure, scan->indexRelation->rd_indexcxt); \
113 } \
114 } while(0)
115
116 static IndexScanDesc index_beginscan_internal(Relation indexRelation,
117 int nkeys, ScanKey key);
118
119
120 /* ----------------------------------------------------------------
121 * index_ interface functions
122 * ----------------------------------------------------------------
123 */
124
125 /* ----------------
126 * index_open - open an index relation by relation OID
127 *
128 * If lockmode is not "NoLock", the specified kind of lock is
129 * obtained on the index. (Generally, NoLock should only be
130 * used if the caller knows it has some appropriate lock on the
131 * index already.)
132 *
133 * An error is raised if the index does not exist.
134 *
135 * This is a convenience routine adapted for indexscan use.
136 * Some callers may prefer to use relation_open directly.
137 * ----------------
138 */
139 Relation
140 index_open(Oid relationId, LOCKMODE lockmode)
141 {
142 Relation r;
143
144 r = relation_open(relationId, lockmode);
145
146 if (r->rd_rel->relkind != RELKIND_INDEX)
147 ereport(ERROR,
148 (errcode(ERRCODE_WRONG_OBJECT_TYPE),
149 errmsg("\"%s\" is not an index",
150 RelationGetRelationName(r))));
151
152 return r;
153 }
154
155 /* ----------------
156 * index_close - close an index relation
157 *
158 * If lockmode is not "NoLock", we then release the specified lock.
159 *
160 * Note that it is often sensible to hold a lock beyond index_close;
161 * in that case, the lock is released automatically at xact end.
162 * ----------------
163 */
164 void
165 index_close(Relation relation, LOCKMODE lockmode)
166 {
167 LockRelId relid = relation->rd_lockInfo.lockRelId;
168
169 Assert(lockmode >= NoLock && lockmode < MAX_LOCKMODES);
170
171 /* The relcache does the real work... */
172 RelationClose(relation);
173
174 if (lockmode != NoLock)
175 UnlockRelationId(&relid, lockmode);
176 }
177
178 /* ----------------
179 * index_insert - insert an index tuple into a relation
180 * ----------------
181 */
182 bool
183 index_insert(Relation indexRelation,
184 Datum *values,
185 bool *isnull,
186 ItemPointer heap_t_ctid,
187 Relation heapRelation,
188 bool check_uniqueness)
189 {
190 FmgrInfo *procedure;
191
192 RELATION_CHECKS;
193 GET_REL_PROCEDURE(aminsert);
194
195 /*
196 * have the am's insert proc do all the work.
197 */
198 return DatumGetBool(FunctionCall6(procedure,
199 PointerGetDatum(indexRelation),
200 PointerGetDatum(values),
201 PointerGetDatum(isnull),
202 PointerGetDatum(heap_t_ctid),
203 PointerGetDatum(heapRelation),
204 BoolGetDatum(check_uniqueness)));
205 }
206
207 /*
208 * index_beginscan - start a scan of an index with amgettuple
209 *
210 * Caller must be holding suitable locks on the heap and the index.
211 */
212 IndexScanDesc
213 index_beginscan(Relation heapRelation,
214 Relation indexRelation,
215 Snapshot snapshot,
216 int nkeys, ScanKey key)
217 {
218 IndexScanDesc scan;
219
220 scan = index_beginscan_internal(indexRelation, nkeys, key);
221
222 /*
223 * Save additional parameters into the scandesc. Everything else was set
224 * up by RelationGetIndexScan.
225 */
226 scan->heapRelation = heapRelation;
227 scan->xs_snapshot = snapshot;
228
229 return scan;
230 }
231
232 /*
233 * index_beginscan_bitmap - start a scan of an index with amgetbitmap
234 *
235 * As above, caller had better be holding some lock on the parent heap
236 * relation, even though it's not explicitly mentioned here.
237 */
238 IndexScanDesc
239 index_beginscan_bitmap(Relation indexRelation,
240 Snapshot snapshot,
241 int nkeys, ScanKey key)
242 {
243 IndexScanDesc scan;
244
245 scan = index_beginscan_internal(indexRelation, nkeys, key);
246
247 /*
248 * Save additional parameters into the scandesc. Everything else was set
249 * up by RelationGetIndexScan.
250 */
251 scan->xs_snapshot = snapshot;
252
253 return scan;
254 }
255
256 /*
257 * index_beginscan_internal --- common code for index_beginscan variants
258 */
259 static IndexScanDesc
260 index_beginscan_internal(Relation indexRelation,
261 int nkeys, ScanKey key)
262 {
263 IndexScanDesc scan;
264 FmgrInfo *procedure;
265
266 RELATION_CHECKS;
267 GET_REL_PROCEDURE(ambeginscan);
268
269 /*
270 * We hold a reference count to the relcache entry throughout the scan.
271 */
272 RelationIncrementReferenceCount(indexRelation);
273
274 /*
275 * Tell the AM to open a scan.
276 */
277 scan = (IndexScanDesc)
278 DatumGetPointer(FunctionCall3(procedure,
279 PointerGetDatum(indexRelation),
280 Int32GetDatum(nkeys),
281 PointerGetDatum(key)));
282
283 return scan;
284 }
285
286 /* ----------------
287 * index_rescan - (re)start a scan of an index
288 *
289 * The caller may specify a new set of scankeys (but the number of keys
290 * cannot change). To restart the scan without changing keys, pass NULL
291 * for the key array.
292 *
293 * Note that this is also called when first starting an indexscan;
294 * see RelationGetIndexScan. Keys *must* be passed in that case,
295 * unless scan->numberOfKeys is zero.
296 * ----------------
297 */
298 void
299 index_rescan(IndexScanDesc scan, ScanKey key)
300 {
301 FmgrInfo *procedure;
302
303 SCAN_CHECKS;
304 GET_SCAN_PROCEDURE(amrescan);
305
306 /* Release any held pin on a heap page */
307 if (BufferIsValid(scan->xs_cbuf))
308 {
309 ReleaseBuffer(scan->xs_cbuf);
310 scan->xs_cbuf = InvalidBuffer;
311 }
312
313 scan->xs_next_hot = InvalidOffsetNumber;
314
315 scan->kill_prior_tuple = false; /* for safety */
316
317 FunctionCall2(procedure,
318 PointerGetDatum(scan),
319 PointerGetDatum(key));
320 }
321
322 /* ----------------
323 * index_endscan - end a scan
324 * ----------------
325 */
326 void
327 index_endscan(IndexScanDesc scan)
328 {
329 FmgrInfo *procedure;
330
331 SCAN_CHECKS;
332 GET_SCAN_PROCEDURE(amendscan);
333
334 /* Release any held pin on a heap page */
335 if (BufferIsValid(scan->xs_cbuf))
336 {
337 ReleaseBuffer(scan->xs_cbuf);
338 scan->xs_cbuf = InvalidBuffer;
339 }
340
341 /* End the AM's scan */
342 FunctionCall1(procedure, PointerGetDatum(scan));
343
344 /* Release index refcount acquired by index_beginscan */
345 RelationDecrementReferenceCount(scan->indexRelation);
346
347 /* Release the scan data structure itself */
348 IndexScanEnd(scan);
349 }
350
351 /* ----------------
352 * index_markpos - mark a scan position
353 * ----------------
354 */
355 void
356 index_markpos(IndexScanDesc scan)
357 {
358 FmgrInfo *procedure;
359
360 SCAN_CHECKS;
361 GET_SCAN_PROCEDURE(ammarkpos);
362
363 FunctionCall1(procedure, PointerGetDatum(scan));
364 }
365
366 /* ----------------
367 * index_restrpos - restore a scan position
368 *
369 * NOTE: this only restores the internal scan state of the index AM.
370 * The current result tuple (scan->xs_ctup) doesn't change. See comments
371 * for ExecRestrPos().
372 *
373 * NOTE: in the presence of HOT chains, mark/restore only works correctly
374 * if the scan's snapshot is MVCC-safe; that ensures that there's at most one
375 * returnable tuple in each HOT chain, and so restoring the prior state at the
376 * granularity of the index AM is sufficient. Since the only current user
377 * of mark/restore functionality is nodeMergejoin.c, this effectively means
378 * that merge-join plans only work for MVCC snapshots. This could be fixed
379 * if necessary, but for now it seems unimportant.
380 * ----------------
381 */
382 void
383 index_restrpos(IndexScanDesc scan)
384 {
385 FmgrInfo *procedure;
386
387 Assert(IsMVCCSnapshot(scan->xs_snapshot));
388
389 SCAN_CHECKS;
390 GET_SCAN_PROCEDURE(amrestrpos);
391
392 scan->xs_next_hot = InvalidOffsetNumber;
393
394 scan->kill_prior_tuple = false; /* for safety */
395
396 FunctionCall1(procedure, PointerGetDatum(scan));
397 }
398
399 /* ----------------
400 * index_getnext - get the next heap tuple from a scan
401 *
402 * The result is the next heap tuple satisfying the scan keys and the
403 * snapshot, or NULL if no more matching tuples exist. On success,
404 * the buffer containing the heap tuple is pinned (the pin will be dropped
405 * at the next index_getnext or index_endscan).
406 *
407 * Note: caller must check scan->xs_recheck, and perform rechecking of the
408 * scan keys if required. We do not do that here because we don't have
409 * enough information to do it efficiently in the general case.
410 * ----------------
411 */
412 HeapTuple
413 index_getnext(IndexScanDesc scan, ScanDirection direction)
414 {
415 HeapTuple heapTuple = &scan->xs_ctup;
416 ItemPointer tid = &heapTuple->t_self;
417 FmgrInfo *procedure;
418
419 SCAN_CHECKS;
420 GET_SCAN_PROCEDURE(amgettuple);
421
422 Assert(TransactionIdIsValid(RecentGlobalXmin));
423
424 /*
425 * We always reset xs_hot_dead; if we are here then either we are just
426 * starting the scan, or we previously returned a visible tuple, and in
427 * either case it's inappropriate to kill the prior index entry.
428 */
429 scan->xs_hot_dead = false;
430
431 for (;;)
432 {
433 OffsetNumber offnum;
434 bool at_chain_start;
435 Page dp;
436
437 if (scan->xs_next_hot != InvalidOffsetNumber)
438 {
439 /*
440 * We are resuming scan of a HOT chain after having returned an
441 * earlier member. Must still hold pin on current heap page.
442 */
443 Assert(BufferIsValid(scan->xs_cbuf));
444 Assert(ItemPointerGetBlockNumber(tid) ==
445 BufferGetBlockNumber(scan->xs_cbuf));
446 Assert(TransactionIdIsValid(scan->xs_prev_xmax));
447 offnum = scan->xs_next_hot;
448 at_chain_start = false;
449 scan->xs_next_hot = InvalidOffsetNumber;
450 }
451 else
452 {
453 bool found;
454 Buffer prev_buf;
455
456 /*
457 * If we scanned a whole HOT chain and found only dead tuples,
458 * tell index AM to kill its entry for that TID.
459 */
460 scan->kill_prior_tuple = scan->xs_hot_dead;
461
462 /*
463 * The AM's gettuple proc finds the next index entry matching the
464 * scan keys, and puts the TID in xs_ctup.t_self (ie, *tid).
465 * It should also set scan->xs_recheck, though we pay no
466 * attention to that here.
467 */
468 found = DatumGetBool(FunctionCall2(procedure,
469 PointerGetDatum(scan),
470 Int32GetDatum(direction)));
471
472 /* Reset kill flag immediately for safety */
473 scan->kill_prior_tuple = false;
474
475 /* If we're out of index entries, break out of outer loop */
476 if (!found)
477 break;
478
479 pgstat_count_index_tuples(scan->indexRelation, 1);
480
481 /* Switch to correct buffer if we don't have it already */
482 prev_buf = scan->xs_cbuf;
483 scan->xs_cbuf = ReleaseAndReadBuffer(scan->xs_cbuf,
484 scan->heapRelation,
485 ItemPointerGetBlockNumber(tid));
486
487 /*
488 * Prune page, but only if we weren't already on this page
489 */
490 if (prev_buf != scan->xs_cbuf)
491 heap_page_prune_opt(scan->heapRelation, scan->xs_cbuf,
492 RecentGlobalXmin);
493
494 /* Prepare to scan HOT chain starting at index-referenced offnum */
495 offnum = ItemPointerGetOffsetNumber(tid);
496 at_chain_start = true;
497
498 /* We don't know what the first tuple's xmin should be */
499 scan->xs_prev_xmax = InvalidTransactionId;
500
501 /* Initialize flag to detect if all entries are dead */
502 scan->xs_hot_dead = true;
503 }
504
505 /* Obtain share-lock on the buffer so we can examine visibility */
506 LockBuffer(scan->xs_cbuf, BUFFER_LOCK_SHARE);
507
508 dp = (Page) BufferGetPage(scan->xs_cbuf);
509
510 /* Scan through possible multiple members of HOT-chain */
511 for (;;)
512 {
513 ItemId lp;
514 ItemPointer ctid;
515
516 /* check for bogus TID */
517 if (offnum < FirstOffsetNumber ||
518 offnum > PageGetMaxOffsetNumber(dp))
519 break;
520
521 lp = PageGetItemId(dp, offnum);
522
523 /* check for unused, dead, or redirected items */
524 if (!ItemIdIsNormal(lp))
525 {
526 /* We should only see a redirect at start of chain */
527 if (ItemIdIsRedirected(lp) && at_chain_start)
528 {
529 /* Follow the redirect */
530 offnum = ItemIdGetRedirect(lp);
531 at_chain_start = false;
532 continue;
533 }
534 /* else must be end of chain */
535 break;
536 }
537
538 /*
539 * We must initialize all of *heapTuple (ie, scan->xs_ctup) since
540 * it is returned to the executor on success.
541 */
542 heapTuple->t_data = (HeapTupleHeader) PageGetItem(dp, lp);
543 heapTuple->t_len = ItemIdGetLength(lp);
544 ItemPointerSetOffsetNumber(tid, offnum);
545 heapTuple->t_tableOid = RelationGetRelid(scan->heapRelation);
546 ctid = &heapTuple->t_data->t_ctid;
547
548 /*
549 * Shouldn't see a HEAP_ONLY tuple at chain start. (This test
550 * should be unnecessary, since the chain root can't be removed
551 * while we have pin on the index entry, but let's make it
552 * anyway.)
553 */
554 if (at_chain_start && HeapTupleIsHeapOnly(heapTuple))
555 break;
556
557 /*
558 * The xmin should match the previous xmax value, else chain is
559 * broken. (Note: this test is not optional because it protects
560 * us against the case where the prior chain member's xmax aborted
561 * since we looked at it.)
562 */
563 if (TransactionIdIsValid(scan->xs_prev_xmax) &&
564 !TransactionIdEquals(scan->xs_prev_xmax,
565 HeapTupleHeaderGetXmin(heapTuple->t_data)))
566 break;
567
568 /* If it's visible per the snapshot, we must return it */
569 if (HeapTupleSatisfiesVisibility(heapTuple, scan->xs_snapshot,
570 scan->xs_cbuf))
571 {
572 /*
573 * If the snapshot is MVCC, we know that it could accept at
574 * most one member of the HOT chain, so we can skip examining
575 * any more members. Otherwise, check for continuation of the
576 * HOT-chain, and set state for next time.
577 */
578 if (IsMVCCSnapshot(scan->xs_snapshot))
579 scan->xs_next_hot = InvalidOffsetNumber;
580 else if (HeapTupleIsHotUpdated(heapTuple))
581 {
582 Assert(ItemPointerGetBlockNumber(ctid) ==
583 ItemPointerGetBlockNumber(tid));
584 scan->xs_next_hot = ItemPointerGetOffsetNumber(ctid);
585 scan->xs_prev_xmax = HeapTupleHeaderGetXmax(heapTuple->t_data);
586 }
587 else
588 scan->xs_next_hot = InvalidOffsetNumber;
589
590 LockBuffer(scan->xs_cbuf, BUFFER_LOCK_UNLOCK);
591
592 pgstat_count_heap_fetch(scan->indexRelation);
593
594 return heapTuple;
595 }
596
597 /*
598 * If we can't see it, maybe no one else can either. Check to see
599 * if the tuple is dead to all transactions. If we find that all
600 * the tuples in the HOT chain are dead, we'll signal the index AM
601 * to not return that TID on future indexscans.
602 */
603 if (scan->xs_hot_dead &&
604 HeapTupleSatisfiesVacuum(heapTuple->t_data, RecentGlobalXmin,
605 scan->xs_cbuf) != HEAPTUPLE_DEAD)
606 scan->xs_hot_dead = false;
607
608 /*
609 * Check to see if HOT chain continues past this tuple; if so
610 * fetch the next offnum (we don't bother storing it into
611 * xs_next_hot, but must store xs_prev_xmax), and loop around.
612 */
613 if (HeapTupleIsHotUpdated(heapTuple))
614 {
615 Assert(ItemPointerGetBlockNumber(ctid) ==
616 ItemPointerGetBlockNumber(tid));
617 offnum = ItemPointerGetOffsetNumber(ctid);
618 at_chain_start = false;
619 scan->xs_prev_xmax = HeapTupleHeaderGetXmax(heapTuple->t_data);
620 }
621 else
622 break; /* end of chain */
623 } /* loop over a single HOT chain */
624
625 LockBuffer(scan->xs_cbuf, BUFFER_LOCK_UNLOCK);
626
627 /* Loop around to ask index AM for another TID */
628 scan->xs_next_hot = InvalidOffsetNumber;
629 }
630
631 /* Release any held pin on a heap page */
632 if (BufferIsValid(scan->xs_cbuf))
633 {
634 ReleaseBuffer(scan->xs_cbuf);
635 scan->xs_cbuf = InvalidBuffer;
636 }
637
638 return NULL; /* failure exit */
639 }
640
641 /* ----------------
642 * index_getbitmap - get all tuples at once from an index scan
643 *
644 * Adds the TIDs of all heap tuples satisfying the scan keys to a bitmap.
645 * Since there's no interlock between the index scan and the eventual heap
646 * access, this is only safe to use with MVCC-based snapshots: the heap
647 * item slot could have been replaced by a newer tuple by the time we get
648 * to it.
649 *
650 * Returns the number of matching tuples found.
651 * ----------------
652 */
653 int64
654 index_getbitmap(IndexScanDesc scan, TIDBitmap *bitmap)
655 {
656 FmgrInfo *procedure;
657 int64 ntids;
658
659 SCAN_CHECKS;
660 GET_SCAN_PROCEDURE(amgetbitmap);
661
662 /* just make sure this is false... */
663 scan->kill_prior_tuple = false;
664
665 /*
666 * have the am's getbitmap proc do all the work.
667 */
668 ntids = DatumGetInt64(FunctionCall2(procedure,
669 PointerGetDatum(scan),
670 PointerGetDatum(bitmap)));
671
672 pgstat_count_index_tuples(scan->indexRelation, ntids);
673
674 return ntids;
675 }
676
677 /* ----------------
678 * index_bulk_delete - do mass deletion of index entries
679 *
680 * callback routine tells whether a given main-heap tuple is
681 * to be deleted
682 *
683 * return value is an optional palloc'd struct of statistics
684 * ----------------
685 */
686 IndexBulkDeleteResult *
687 index_bulk_delete(IndexVacuumInfo *info,
688 IndexBulkDeleteResult *stats,
689 IndexBulkDeleteCallback callback,
690 void *callback_state)
691 {
692 Relation indexRelation = info->index;
693 FmgrInfo *procedure;
694 IndexBulkDeleteResult *result;
695
696 RELATION_CHECKS;
697 GET_REL_PROCEDURE(ambulkdelete);
698
699 result = (IndexBulkDeleteResult *)
700 DatumGetPointer(FunctionCall4(procedure,
701 PointerGetDatum(info),
702 PointerGetDatum(stats),
703 PointerGetDatum((Pointer) callback),
704 PointerGetDatum(callback_state)));
705
706 return result;
707 }
708
709 /* ----------------
710 * index_vacuum_cleanup - do post-deletion cleanup of an index
711 *
712 * return value is an optional palloc'd struct of statistics
713 * ----------------
714 */
715 IndexBulkDeleteResult *
716 index_vacuum_cleanup(IndexVacuumInfo *info,
717 IndexBulkDeleteResult *stats)
718 {
719 Relation indexRelation = info->index;
720 FmgrInfo *procedure;
721 IndexBulkDeleteResult *result;
722
723 RELATION_CHECKS;
724 GET_REL_PROCEDURE(amvacuumcleanup);
725
726 result = (IndexBulkDeleteResult *)
727 DatumGetPointer(FunctionCall2(procedure,
728 PointerGetDatum(info),
729 PointerGetDatum(stats)));
730
731 return result;
732 }
733
734 /* ----------------
735 * index_getprocid
736 *
737 * Index access methods typically require support routines that are
738 * not directly the implementation of any WHERE-clause query operator
739 * and so cannot be kept in pg_amop. Instead, such routines are kept
740 * in pg_amproc. These registered procedure OIDs are assigned numbers
741 * according to a convention established by the access method.
742 * The general index code doesn't know anything about the routines
743 * involved; it just builds an ordered list of them for
744 * each attribute on which an index is defined.
745 *
746 * As of Postgres 8.3, support routines within an operator family
747 * are further subdivided by the "left type" and "right type" of the
748 * query operator(s) that they support. The "default" functions for a
749 * particular indexed attribute are those with both types equal to
750 * the index opclass' opcintype (note that this is subtly different
751 * from the indexed attribute's own type: it may be a binary-compatible
752 * type instead). Only the default functions are stored in relcache
753 * entries --- access methods can use the syscache to look up non-default
754 * functions.
755 *
756 * This routine returns the requested default procedure OID for a
757 * particular indexed attribute.
758 * ----------------
759 */
760 RegProcedure
761 index_getprocid(Relation irel,
762 AttrNumber attnum,
763 uint16 procnum)
764 {
765 RegProcedure *loc;
766 int nproc;
767 int procindex;
768
769 nproc = irel->rd_am->amsupport;
770
771 Assert(procnum > 0 && procnum <= (uint16) nproc);
772
773 procindex = (nproc * (attnum - 1)) + (procnum - 1);
774
775 loc = irel->rd_support;
776
777 Assert(loc != NULL);
778
779 return loc[procindex];
780 }
781
782 /* ----------------
783 * index_getprocinfo
784 *
785 * This routine allows index AMs to keep fmgr lookup info for
786 * support procs in the relcache. As above, only the "default"
787 * functions for any particular indexed attribute are cached.
788 *
789 * Note: the return value points into cached data that will be lost during
790 * any relcache rebuild! Therefore, either use the callinfo right away,
791 * or save it only after having acquired some type of lock on the index rel.
792 * ----------------
793 */
794 FmgrInfo *
795 index_getprocinfo(Relation irel,
796 AttrNumber attnum,
797 uint16 procnum)
798 {
799 FmgrInfo *locinfo;
800 int nproc;
801 int procindex;
802
803 nproc = irel->rd_am->amsupport;
804
805 Assert(procnum > 0 && procnum <= (uint16) nproc);
806
807 procindex = (nproc * (attnum - 1)) + (procnum - 1);
808
809 locinfo = irel->rd_supportinfo;
810
811 Assert(locinfo != NULL);
812
813 locinfo += procindex;
814
815 /* Initialize the lookup info if first time through */
816 if (locinfo->fn_oid == InvalidOid)
817 {
818 RegProcedure *loc = irel->rd_support;
819 RegProcedure procId;
820
821 Assert(loc != NULL);
822
823 procId = loc[procindex];
824
825 /*
826 * Complain if function was not found during IndexSupportInitialize.
827 * This should not happen unless the system tables contain bogus
828 * entries for the index opclass. (If an AM wants to allow a support
829 * function to be optional, it can use index_getprocid.)
830 */
831 if (!RegProcedureIsValid(procId))
832 elog(ERROR, "missing support function %d for attribute %d of index \"%s\"",
833 procnum, attnum, RelationGetRelationName(irel));
834
835 fmgr_info_cxt(procId, locinfo, irel->rd_indexcxt);
836 }
837
838 return locinfo;
839 }
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