1/*-------------------------------------------------------------------------
2 *
3 * indexam.c
4 * general index access method routines
5 *
6 * Portions Copyright (c) 1996-2019, 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_parallelscan_estimate - estimate shared memory for parallel scan
24 * index_parallelscan_initialize - initialize parallel scan
25 * index_parallelrescan - (re)start a parallel scan of an index
26 * index_beginscan_parallel - join parallel index scan
27 * index_getnext_tid - get the next TID from a scan
28 * index_fetch_heap - get the scan's next heap tuple
29 * index_getnext_slot - get the next tuple from a scan
30 * index_getbitmap - get all tuples from a scan
31 * index_bulk_delete - bulk deletion of index tuples
32 * index_vacuum_cleanup - post-deletion cleanup of an index
33 * index_can_return - does index support index-only scans?
34 * index_getprocid - get a support procedure OID
35 * index_getprocinfo - get a support procedure's lookup info
36 *
37 * NOTES
38 * This file contains the index_ routines which used
39 * to be a scattered collection of stuff in access/genam.
40 *
41 *-------------------------------------------------------------------------
42 */
43
44#include "postgres.h"
45
46#include "access/amapi.h"
47#include "access/heapam.h"
48#include "access/relscan.h"
49#include "access/tableam.h"
50#include "access/transam.h"
51#include "access/xlog.h"
52#include "catalog/index.h"
53#include "catalog/pg_type.h"
54#include "pgstat.h"
55#include "storage/bufmgr.h"
56#include "storage/lmgr.h"
57#include "storage/predicate.h"
58#include "utils/snapmgr.h"
59
60
61/* ----------------------------------------------------------------
62 * macros used in index_ routines
63 *
64 * Note: the ReindexIsProcessingIndex() check in RELATION_CHECKS is there
65 * to check that we don't try to scan or do retail insertions into an index
66 * that is currently being rebuilt or pending rebuild. This helps to catch
67 * things that don't work when reindexing system catalogs. The assertion
68 * doesn't prevent the actual rebuild because we don't use RELATION_CHECKS
69 * when calling the index AM's ambuild routine, and there is no reason for
70 * ambuild to call its subsidiary routines through this file.
71 * ----------------------------------------------------------------
72 */
73#define RELATION_CHECKS \
74( \
75 AssertMacro(RelationIsValid(indexRelation)), \
76 AssertMacro(PointerIsValid(indexRelation->rd_indam)), \
77 AssertMacro(!ReindexIsProcessingIndex(RelationGetRelid(indexRelation))) \
78)
79
80#define SCAN_CHECKS \
81( \
82 AssertMacro(IndexScanIsValid(scan)), \
83 AssertMacro(RelationIsValid(scan->indexRelation)), \
84 AssertMacro(PointerIsValid(scan->indexRelation->rd_indam)) \
85)
86
87#define CHECK_REL_PROCEDURE(pname) \
88do { \
89 if (indexRelation->rd_indam->pname == NULL) \
90 elog(ERROR, "function %s is not defined for index %s", \
91 CppAsString(pname), RelationGetRelationName(indexRelation)); \
92} while(0)
93
94#define CHECK_SCAN_PROCEDURE(pname) \
95do { \
96 if (scan->indexRelation->rd_indam->pname == NULL) \
97 elog(ERROR, "function %s is not defined for index %s", \
98 CppAsString(pname), RelationGetRelationName(scan->indexRelation)); \
99} while(0)
100
101static IndexScanDesc index_beginscan_internal(Relation indexRelation,
102 int nkeys, int norderbys, Snapshot snapshot,
103 ParallelIndexScanDesc pscan, bool temp_snap);
104
105
106/* ----------------------------------------------------------------
107 * index_ interface functions
108 * ----------------------------------------------------------------
109 */
110
111/* ----------------
112 * index_open - open an index relation by relation OID
113 *
114 * If lockmode is not "NoLock", the specified kind of lock is
115 * obtained on the index. (Generally, NoLock should only be
116 * used if the caller knows it has some appropriate lock on the
117 * index already.)
118 *
119 * An error is raised if the index does not exist.
120 *
121 * This is a convenience routine adapted for indexscan use.
122 * Some callers may prefer to use relation_open directly.
123 * ----------------
124 */
125Relation
126index_open(Oid relationId, LOCKMODE lockmode)
127{
128 Relation r;
129
130 r = relation_open(relationId, lockmode);
131
132 if (r->rd_rel->relkind != RELKIND_INDEX &&
133 r->rd_rel->relkind != RELKIND_PARTITIONED_INDEX)
134 ereport(ERROR,
135 (errcode(ERRCODE_WRONG_OBJECT_TYPE),
136 errmsg("\"%s\" is not an index",
137 RelationGetRelationName(r))));
138
139 return r;
140}
141
142/* ----------------
143 * index_close - close an index relation
144 *
145 * If lockmode is not "NoLock", we then release the specified lock.
146 *
147 * Note that it is often sensible to hold a lock beyond index_close;
148 * in that case, the lock is released automatically at xact end.
149 * ----------------
150 */
151void
152index_close(Relation relation, LOCKMODE lockmode)
153{
154 LockRelId relid = relation->rd_lockInfo.lockRelId;
155
156 Assert(lockmode >= NoLock && lockmode < MAX_LOCKMODES);
157
158 /* The relcache does the real work... */
159 RelationClose(relation);
160
161 if (lockmode != NoLock)
162 UnlockRelationId(&relid, lockmode);
163}
164
165/* ----------------
166 * index_insert - insert an index tuple into a relation
167 * ----------------
168 */
169bool
170index_insert(Relation indexRelation,
171 Datum *values,
172 bool *isnull,
173 ItemPointer heap_t_ctid,
174 Relation heapRelation,
175 IndexUniqueCheck checkUnique,
176 IndexInfo *indexInfo)
177{
178 RELATION_CHECKS;
179 CHECK_REL_PROCEDURE(aminsert);
180
181 if (!(indexRelation->rd_indam->ampredlocks))
182 CheckForSerializableConflictIn(indexRelation,
183 (HeapTuple) NULL,
184 InvalidBuffer);
185
186 return indexRelation->rd_indam->aminsert(indexRelation, values, isnull,
187 heap_t_ctid, heapRelation,
188 checkUnique, indexInfo);
189}
190
191/*
192 * index_beginscan - start a scan of an index with amgettuple
193 *
194 * Caller must be holding suitable locks on the heap and the index.
195 */
196IndexScanDesc
197index_beginscan(Relation heapRelation,
198 Relation indexRelation,
199 Snapshot snapshot,
200 int nkeys, int norderbys)
201{
202 IndexScanDesc scan;
203
204 scan = index_beginscan_internal(indexRelation, nkeys, norderbys, snapshot, NULL, false);
205
206 /*
207 * Save additional parameters into the scandesc. Everything else was set
208 * up by RelationGetIndexScan.
209 */
210 scan->heapRelation = heapRelation;
211 scan->xs_snapshot = snapshot;
212
213 /* prepare to fetch index matches from table */
214 scan->xs_heapfetch = table_index_fetch_begin(heapRelation);
215
216 return scan;
217}
218
219/*
220 * index_beginscan_bitmap - start a scan of an index with amgetbitmap
221 *
222 * As above, caller had better be holding some lock on the parent heap
223 * relation, even though it's not explicitly mentioned here.
224 */
225IndexScanDesc
226index_beginscan_bitmap(Relation indexRelation,
227 Snapshot snapshot,
228 int nkeys)
229{
230 IndexScanDesc scan;
231
232 scan = index_beginscan_internal(indexRelation, nkeys, 0, snapshot, NULL, false);
233
234 /*
235 * Save additional parameters into the scandesc. Everything else was set
236 * up by RelationGetIndexScan.
237 */
238 scan->xs_snapshot = snapshot;
239
240 return scan;
241}
242
243/*
244 * index_beginscan_internal --- common code for index_beginscan variants
245 */
246static IndexScanDesc
247index_beginscan_internal(Relation indexRelation,
248 int nkeys, int norderbys, Snapshot snapshot,
249 ParallelIndexScanDesc pscan, bool temp_snap)
250{
251 IndexScanDesc scan;
252
253 RELATION_CHECKS;
254 CHECK_REL_PROCEDURE(ambeginscan);
255
256 if (!(indexRelation->rd_indam->ampredlocks))
257 PredicateLockRelation(indexRelation, snapshot);
258
259 /*
260 * We hold a reference count to the relcache entry throughout the scan.
261 */
262 RelationIncrementReferenceCount(indexRelation);
263
264 /*
265 * Tell the AM to open a scan.
266 */
267 scan = indexRelation->rd_indam->ambeginscan(indexRelation, nkeys,
268 norderbys);
269 /* Initialize information for parallel scan. */
270 scan->parallel_scan = pscan;
271 scan->xs_temp_snap = temp_snap;
272
273 return scan;
274}
275
276/* ----------------
277 * index_rescan - (re)start a scan of an index
278 *
279 * During a restart, the caller may specify a new set of scankeys and/or
280 * orderbykeys; but the number of keys cannot differ from what index_beginscan
281 * was told. (Later we might relax that to "must not exceed", but currently
282 * the index AMs tend to assume that scan->numberOfKeys is what to believe.)
283 * To restart the scan without changing keys, pass NULL for the key arrays.
284 * (Of course, keys *must* be passed on the first call, unless
285 * scan->numberOfKeys is zero.)
286 * ----------------
287 */
288void
289index_rescan(IndexScanDesc scan,
290 ScanKey keys, int nkeys,
291 ScanKey orderbys, int norderbys)
292{
293 SCAN_CHECKS;
294 CHECK_SCAN_PROCEDURE(amrescan);
295
296 Assert(nkeys == scan->numberOfKeys);
297 Assert(norderbys == scan->numberOfOrderBys);
298
299 /* Release resources (like buffer pins) from table accesses */
300 if (scan->xs_heapfetch)
301 table_index_fetch_reset(scan->xs_heapfetch);
302
303 scan->kill_prior_tuple = false; /* for safety */
304 scan->xs_heap_continue = false;
305
306 scan->indexRelation->rd_indam->amrescan(scan, keys, nkeys,
307 orderbys, norderbys);
308}
309
310/* ----------------
311 * index_endscan - end a scan
312 * ----------------
313 */
314void
315index_endscan(IndexScanDesc scan)
316{
317 SCAN_CHECKS;
318 CHECK_SCAN_PROCEDURE(amendscan);
319
320 /* Release resources (like buffer pins) from table accesses */
321 if (scan->xs_heapfetch)
322 {
323 table_index_fetch_end(scan->xs_heapfetch);
324 scan->xs_heapfetch = NULL;
325 }
326
327 /* End the AM's scan */
328 scan->indexRelation->rd_indam->amendscan(scan);
329
330 /* Release index refcount acquired by index_beginscan */
331 RelationDecrementReferenceCount(scan->indexRelation);
332
333 if (scan->xs_temp_snap)
334 UnregisterSnapshot(scan->xs_snapshot);
335
336 /* Release the scan data structure itself */
337 IndexScanEnd(scan);
338}
339
340/* ----------------
341 * index_markpos - mark a scan position
342 * ----------------
343 */
344void
345index_markpos(IndexScanDesc scan)
346{
347 SCAN_CHECKS;
348 CHECK_SCAN_PROCEDURE(ammarkpos);
349
350 scan->indexRelation->rd_indam->ammarkpos(scan);
351}
352
353/* ----------------
354 * index_restrpos - restore a scan position
355 *
356 * NOTE: this only restores the internal scan state of the index AM. See
357 * comments for ExecRestrPos().
358 *
359 * NOTE: For heap, in the presence of HOT chains, mark/restore only works
360 * correctly if the scan's snapshot is MVCC-safe; that ensures that there's at
361 * most one returnable tuple in each HOT chain, and so restoring the prior
362 * state at the granularity of the index AM is sufficient. Since the only
363 * current user of mark/restore functionality is nodeMergejoin.c, this
364 * effectively means that merge-join plans only work for MVCC snapshots. This
365 * could be fixed if necessary, but for now it seems unimportant.
366 * ----------------
367 */
368void
369index_restrpos(IndexScanDesc scan)
370{
371 Assert(IsMVCCSnapshot(scan->xs_snapshot));
372
373 SCAN_CHECKS;
374 CHECK_SCAN_PROCEDURE(amrestrpos);
375
376 /* release resources (like buffer pins) from table accesses */
377 if (scan->xs_heapfetch)
378 table_index_fetch_reset(scan->xs_heapfetch);
379
380 scan->kill_prior_tuple = false; /* for safety */
381 scan->xs_heap_continue = false;
382
383 scan->indexRelation->rd_indam->amrestrpos(scan);
384}
385
386/*
387 * index_parallelscan_estimate - estimate shared memory for parallel scan
388 *
389 * Currently, we don't pass any information to the AM-specific estimator,
390 * so it can probably only return a constant. In the future, we might need
391 * to pass more information.
392 */
393Size
394index_parallelscan_estimate(Relation indexRelation, Snapshot snapshot)
395{
396 Size nbytes;
397
398 RELATION_CHECKS;
399
400 nbytes = offsetof(ParallelIndexScanDescData, ps_snapshot_data);
401 nbytes = add_size(nbytes, EstimateSnapshotSpace(snapshot));
402 nbytes = MAXALIGN(nbytes);
403
404 /*
405 * If amestimateparallelscan is not provided, assume there is no
406 * AM-specific data needed. (It's hard to believe that could work, but
407 * it's easy enough to cater to it here.)
408 */
409 if (indexRelation->rd_indam->amestimateparallelscan != NULL)
410 nbytes = add_size(nbytes,
411 indexRelation->rd_indam->amestimateparallelscan());
412
413 return nbytes;
414}
415
416/*
417 * index_parallelscan_initialize - initialize parallel scan
418 *
419 * We initialize both the ParallelIndexScanDesc proper and the AM-specific
420 * information which follows it.
421 *
422 * This function calls access method specific initialization routine to
423 * initialize am specific information. Call this just once in the leader
424 * process; then, individual workers attach via index_beginscan_parallel.
425 */
426void
427index_parallelscan_initialize(Relation heapRelation, Relation indexRelation,
428 Snapshot snapshot, ParallelIndexScanDesc target)
429{
430 Size offset;
431
432 RELATION_CHECKS;
433
434 offset = add_size(offsetof(ParallelIndexScanDescData, ps_snapshot_data),
435 EstimateSnapshotSpace(snapshot));
436 offset = MAXALIGN(offset);
437
438 target->ps_relid = RelationGetRelid(heapRelation);
439 target->ps_indexid = RelationGetRelid(indexRelation);
440 target->ps_offset = offset;
441 SerializeSnapshot(snapshot, target->ps_snapshot_data);
442
443 /* aminitparallelscan is optional; assume no-op if not provided by AM */
444 if (indexRelation->rd_indam->aminitparallelscan != NULL)
445 {
446 void *amtarget;
447
448 amtarget = OffsetToPointer(target, offset);
449 indexRelation->rd_indam->aminitparallelscan(amtarget);
450 }
451}
452
453/* ----------------
454 * index_parallelrescan - (re)start a parallel scan of an index
455 * ----------------
456 */
457void
458index_parallelrescan(IndexScanDesc scan)
459{
460 SCAN_CHECKS;
461
462 if (scan->xs_heapfetch)
463 table_index_fetch_reset(scan->xs_heapfetch);
464
465 /* amparallelrescan is optional; assume no-op if not provided by AM */
466 if (scan->indexRelation->rd_indam->amparallelrescan != NULL)
467 scan->indexRelation->rd_indam->amparallelrescan(scan);
468}
469
470/*
471 * index_beginscan_parallel - join parallel index scan
472 *
473 * Caller must be holding suitable locks on the heap and the index.
474 */
475IndexScanDesc
476index_beginscan_parallel(Relation heaprel, Relation indexrel, int nkeys,
477 int norderbys, ParallelIndexScanDesc pscan)
478{
479 Snapshot snapshot;
480 IndexScanDesc scan;
481
482 Assert(RelationGetRelid(heaprel) == pscan->ps_relid);
483 snapshot = RestoreSnapshot(pscan->ps_snapshot_data);
484 RegisterSnapshot(snapshot);
485 scan = index_beginscan_internal(indexrel, nkeys, norderbys, snapshot,
486 pscan, true);
487
488 /*
489 * Save additional parameters into the scandesc. Everything else was set
490 * up by index_beginscan_internal.
491 */
492 scan->heapRelation = heaprel;
493 scan->xs_snapshot = snapshot;
494
495 /* prepare to fetch index matches from table */
496 scan->xs_heapfetch = table_index_fetch_begin(heaprel);
497
498 return scan;
499}
500
501/* ----------------
502 * index_getnext_tid - get the next TID from a scan
503 *
504 * The result is the next TID satisfying the scan keys,
505 * or NULL if no more matching tuples exist.
506 * ----------------
507 */
508ItemPointer
509index_getnext_tid(IndexScanDesc scan, ScanDirection direction)
510{
511 bool found;
512
513 SCAN_CHECKS;
514 CHECK_SCAN_PROCEDURE(amgettuple);
515
516 Assert(TransactionIdIsValid(RecentGlobalXmin));
517
518 /*
519 * The AM's amgettuple proc finds the next index entry matching the scan
520 * keys, and puts the TID into scan->xs_heaptid. It should also set
521 * scan->xs_recheck and possibly scan->xs_itup/scan->xs_hitup, though we
522 * pay no attention to those fields here.
523 */
524 found = scan->indexRelation->rd_indam->amgettuple(scan, direction);
525
526 /* Reset kill flag immediately for safety */
527 scan->kill_prior_tuple = false;
528 scan->xs_heap_continue = false;
529
530 /* If we're out of index entries, we're done */
531 if (!found)
532 {
533 /* release resources (like buffer pins) from table accesses */
534 if (scan->xs_heapfetch)
535 table_index_fetch_reset(scan->xs_heapfetch);
536
537 return NULL;
538 }
539 Assert(ItemPointerIsValid(&scan->xs_heaptid));
540
541 pgstat_count_index_tuples(scan->indexRelation, 1);
542
543 /* Return the TID of the tuple we found. */
544 return &scan->xs_heaptid;
545}
546
547/* ----------------
548 * index_fetch_heap - get the scan's next heap tuple
549 *
550 * The result is a visible heap tuple associated with the index TID most
551 * recently fetched by index_getnext_tid, or NULL if no more matching tuples
552 * exist. (There can be more than one matching tuple because of HOT chains,
553 * although when using an MVCC snapshot it should be impossible for more than
554 * one such tuple to exist.)
555 *
556 * On success, the buffer containing the heap tup is pinned (the pin will be
557 * dropped in a future index_getnext_tid, index_fetch_heap or index_endscan
558 * call).
559 *
560 * Note: caller must check scan->xs_recheck, and perform rechecking of the
561 * scan keys if required. We do not do that here because we don't have
562 * enough information to do it efficiently in the general case.
563 * ----------------
564 */
565bool
566index_fetch_heap(IndexScanDesc scan, TupleTableSlot *slot)
567{
568 bool all_dead = false;
569 bool found;
570
571 found = table_index_fetch_tuple(scan->xs_heapfetch, &scan->xs_heaptid,
572 scan->xs_snapshot, slot,
573 &scan->xs_heap_continue, &all_dead);
574
575 if (found)
576 pgstat_count_heap_fetch(scan->indexRelation);
577
578 /*
579 * If we scanned a whole HOT chain and found only dead tuples, tell index
580 * AM to kill its entry for that TID (this will take effect in the next
581 * amgettuple call, in index_getnext_tid). We do not do this when in
582 * recovery because it may violate MVCC to do so. See comments in
583 * RelationGetIndexScan().
584 */
585 if (!scan->xactStartedInRecovery)
586 scan->kill_prior_tuple = all_dead;
587
588 return found;
589}
590
591/* ----------------
592 * index_getnext_slot - get the next tuple from a scan
593 *
594 * The result is true if a tuple satisfying the scan keys and the snapshot was
595 * found, false otherwise. The tuple is stored in the specified slot.
596 *
597 * On success, resources (like buffer pins) are likely to be held, and will be
598 * dropped by a future index_getnext_tid, index_fetch_heap or index_endscan
599 * call).
600 *
601 * Note: caller must check scan->xs_recheck, and perform rechecking of the
602 * scan keys if required. We do not do that here because we don't have
603 * enough information to do it efficiently in the general case.
604 * ----------------
605 */
606bool
607index_getnext_slot(IndexScanDesc scan, ScanDirection direction, TupleTableSlot *slot)
608{
609 for (;;)
610 {
611 if (!scan->xs_heap_continue)
612 {
613 ItemPointer tid;
614
615 /* Time to fetch the next TID from the index */
616 tid = index_getnext_tid(scan, direction);
617
618 /* If we're out of index entries, we're done */
619 if (tid == NULL)
620 break;
621
622 Assert(ItemPointerEquals(tid, &scan->xs_heaptid));
623 }
624
625 /*
626 * Fetch the next (or only) visible heap tuple for this index entry.
627 * If we don't find anything, loop around and grab the next TID from
628 * the index.
629 */
630 Assert(ItemPointerIsValid(&scan->xs_heaptid));
631 if (index_fetch_heap(scan, slot))
632 return true;
633 }
634
635 return false;
636}
637
638/* ----------------
639 * index_getbitmap - get all tuples at once from an index scan
640 *
641 * Adds the TIDs of all heap tuples satisfying the scan keys to a bitmap.
642 * Since there's no interlock between the index scan and the eventual heap
643 * access, this is only safe to use with MVCC-based snapshots: the heap
644 * item slot could have been replaced by a newer tuple by the time we get
645 * to it.
646 *
647 * Returns the number of matching tuples found. (Note: this might be only
648 * approximate, so it should only be used for statistical purposes.)
649 * ----------------
650 */
651int64
652index_getbitmap(IndexScanDesc scan, TIDBitmap *bitmap)
653{
654 int64 ntids;
655
656 SCAN_CHECKS;
657 CHECK_SCAN_PROCEDURE(amgetbitmap);
658
659 /* just make sure this is false... */
660 scan->kill_prior_tuple = false;
661
662 /*
663 * have the am's getbitmap proc do all the work.
664 */
665 ntids = scan->indexRelation->rd_indam->amgetbitmap(scan, bitmap);
666
667 pgstat_count_index_tuples(scan->indexRelation, ntids);
668
669 return ntids;
670}
671
672/* ----------------
673 * index_bulk_delete - do mass deletion of index entries
674 *
675 * callback routine tells whether a given main-heap tuple is
676 * to be deleted
677 *
678 * return value is an optional palloc'd struct of statistics
679 * ----------------
680 */
681IndexBulkDeleteResult *
682index_bulk_delete(IndexVacuumInfo *info,
683 IndexBulkDeleteResult *stats,
684 IndexBulkDeleteCallback callback,
685 void *callback_state)
686{
687 Relation indexRelation = info->index;
688
689 RELATION_CHECKS;
690 CHECK_REL_PROCEDURE(ambulkdelete);
691
692 return indexRelation->rd_indam->ambulkdelete(info, stats,
693 callback, callback_state);
694}
695
696/* ----------------
697 * index_vacuum_cleanup - do post-deletion cleanup of an index
698 *
699 * return value is an optional palloc'd struct of statistics
700 * ----------------
701 */
702IndexBulkDeleteResult *
703index_vacuum_cleanup(IndexVacuumInfo *info,
704 IndexBulkDeleteResult *stats)
705{
706 Relation indexRelation = info->index;
707
708 RELATION_CHECKS;
709 CHECK_REL_PROCEDURE(amvacuumcleanup);
710
711 return indexRelation->rd_indam->amvacuumcleanup(info, stats);
712}
713
714/* ----------------
715 * index_can_return
716 *
717 * Does the index access method support index-only scans for the given
718 * column?
719 * ----------------
720 */
721bool
722index_can_return(Relation indexRelation, int attno)
723{
724 RELATION_CHECKS;
725
726 /* amcanreturn is optional; assume false if not provided by AM */
727 if (indexRelation->rd_indam->amcanreturn == NULL)
728 return false;
729
730 return indexRelation->rd_indam->amcanreturn(indexRelation, attno);
731}
732
733/* ----------------
734 * index_getprocid
735 *
736 * Index access methods typically require support routines that are
737 * not directly the implementation of any WHERE-clause query operator
738 * and so cannot be kept in pg_amop. Instead, such routines are kept
739 * in pg_amproc. These registered procedure OIDs are assigned numbers
740 * according to a convention established by the access method.
741 * The general index code doesn't know anything about the routines
742 * involved; it just builds an ordered list of them for
743 * each attribute on which an index is defined.
744 *
745 * As of Postgres 8.3, support routines within an operator family
746 * are further subdivided by the "left type" and "right type" of the
747 * query operator(s) that they support. The "default" functions for a
748 * particular indexed attribute are those with both types equal to
749 * the index opclass' opcintype (note that this is subtly different
750 * from the indexed attribute's own type: it may be a binary-compatible
751 * type instead). Only the default functions are stored in relcache
752 * entries --- access methods can use the syscache to look up non-default
753 * functions.
754 *
755 * This routine returns the requested default procedure OID for a
756 * particular indexed attribute.
757 * ----------------
758 */
759RegProcedure
760index_getprocid(Relation irel,
761 AttrNumber attnum,
762 uint16 procnum)
763{
764 RegProcedure *loc;
765 int nproc;
766 int procindex;
767
768 nproc = irel->rd_indam->amsupport;
769
770 Assert(procnum > 0 && procnum <= (uint16) nproc);
771
772 procindex = (nproc * (attnum - 1)) + (procnum - 1);
773
774 loc = irel->rd_support;
775
776 Assert(loc != NULL);
777
778 return loc[procindex];
779}
780
781/* ----------------
782 * index_getprocinfo
783 *
784 * This routine allows index AMs to keep fmgr lookup info for
785 * support procs in the relcache. As above, only the "default"
786 * functions for any particular indexed attribute are cached.
787 *
788 * Note: the return value points into cached data that will be lost during
789 * any relcache rebuild! Therefore, either use the callinfo right away,
790 * or save it only after having acquired some type of lock on the index rel.
791 * ----------------
792 */
793FmgrInfo *
794index_getprocinfo(Relation irel,
795 AttrNumber attnum,
796 uint16 procnum)
797{
798 FmgrInfo *locinfo;
799 int nproc;
800 int procindex;
801
802 nproc = irel->rd_indam->amsupport;
803
804 Assert(procnum > 0 && procnum <= (uint16) nproc);
805
806 procindex = (nproc * (attnum - 1)) + (procnum - 1);
807
808 locinfo = irel->rd_supportinfo;
809
810 Assert(locinfo != NULL);
811
812 locinfo += procindex;
813
814 /* Initialize the lookup info if first time through */
815 if (locinfo->fn_oid == InvalidOid)
816 {
817 RegProcedure *loc = irel->rd_support;
818 RegProcedure procId;
819
820 Assert(loc != NULL);
821
822 procId = loc[procindex];
823
824 /*
825 * Complain if function was not found during IndexSupportInitialize.
826 * This should not happen unless the system tables contain bogus
827 * entries for the index opclass. (If an AM wants to allow a support
828 * function to be optional, it can use index_getprocid.)
829 */
830 if (!RegProcedureIsValid(procId))
831 elog(ERROR, "missing support function %d for attribute %d of index \"%s\"",
832 procnum, attnum, RelationGetRelationName(irel));
833
834 fmgr_info_cxt(procId, locinfo, irel->rd_indexcxt);
835 }
836
837 return locinfo;
838}
839
840/* ----------------
841 * index_store_float8_orderby_distances
842 *
843 * Convert AM distance function's results (that can be inexact)
844 * to ORDER BY types and save them into xs_orderbyvals/xs_orderbynulls
845 * for a possible recheck.
846 * ----------------
847 */
848void
849index_store_float8_orderby_distances(IndexScanDesc scan, Oid *orderByTypes,
850 IndexOrderByDistance *distances,
851 bool recheckOrderBy)
852{
853 int i;
854
855 Assert(distances || !recheckOrderBy);
856
857 scan->xs_recheckorderby = recheckOrderBy;
858
859 for (i = 0; i < scan->numberOfOrderBys; i++)
860 {
861 if (orderByTypes[i] == FLOAT8OID)
862 {
863#ifndef USE_FLOAT8_BYVAL
864 /* must free any old value to avoid memory leakage */
865 if (!scan->xs_orderbynulls[i])
866 pfree(DatumGetPointer(scan->xs_orderbyvals[i]));
867#endif
868 if (distances && !distances[i].isnull)
869 {
870 scan->xs_orderbyvals[i] = Float8GetDatum(distances[i].value);
871 scan->xs_orderbynulls[i] = false;
872 }
873 else
874 {
875 scan->xs_orderbyvals[i] = (Datum) 0;
876 scan->xs_orderbynulls[i] = true;
877 }
878 }
879 else if (orderByTypes[i] == FLOAT4OID)
880 {
881 /* convert distance function's result to ORDER BY type */
882#ifndef USE_FLOAT4_BYVAL
883 /* must free any old value to avoid memory leakage */
884 if (!scan->xs_orderbynulls[i])
885 pfree(DatumGetPointer(scan->xs_orderbyvals[i]));
886#endif
887 if (distances && !distances[i].isnull)
888 {
889 scan->xs_orderbyvals[i] = Float4GetDatum((float4) distances[i].value);
890 scan->xs_orderbynulls[i] = false;
891 }
892 else
893 {
894 scan->xs_orderbyvals[i] = (Datum) 0;
895 scan->xs_orderbynulls[i] = true;
896 }
897 }
898 else
899 {
900 /*
901 * If the ordering operator's return value is anything else, we
902 * don't know how to convert the float8 bound calculated by the
903 * distance function to that. The executor won't actually need
904 * the order by values we return here, if there are no lossy
905 * results, so only insist on converting if the *recheck flag is
906 * set.
907 */
908 if (scan->xs_recheckorderby)
909 elog(ERROR, "ORDER BY operator must return float8 or float4 if the distance function is lossy");
910 scan->xs_orderbynulls[i] = true;
911 }
912 }
913}
914