Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * indexam.c
4 : * general index access method routines
5 : *
6 : * Portions Copyright (c) 1996-2017, 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 - get the next heap 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 : * old comments
43 : * Scans are implemented as follows:
44 : *
45 : * `0' represents an invalid item pointer.
46 : * `-' represents an unknown item pointer.
47 : * `X' represents a known item pointers.
48 : * `+' represents known or invalid item pointers.
49 : * `*' represents any item pointers.
50 : *
51 : * State is represented by a triple of these symbols in the order of
52 : * previous, current, next. Note that the case of reverse scans works
53 : * identically.
54 : *
55 : * State Result
56 : * (1) + + - + 0 0 (if the next item pointer is invalid)
57 : * (2) + X - (otherwise)
58 : * (3) * 0 0 * 0 0 (no change)
59 : * (4) + X 0 X 0 0 (shift)
60 : * (5) * + X + X - (shift, add unknown)
61 : *
62 : * All other states cannot occur.
63 : *
64 : * Note: It would be possible to cache the status of the previous and
65 : * next item pointer using the flags.
66 : *
67 : *-------------------------------------------------------------------------
68 : */
69 :
70 : #include "postgres.h"
71 :
72 : #include "access/amapi.h"
73 : #include "access/relscan.h"
74 : #include "access/transam.h"
75 : #include "access/xlog.h"
76 : #include "catalog/catalog.h"
77 : #include "catalog/index.h"
78 : #include "pgstat.h"
79 : #include "storage/bufmgr.h"
80 : #include "storage/lmgr.h"
81 : #include "storage/predicate.h"
82 : #include "utils/snapmgr.h"
83 : #include "utils/tqual.h"
84 :
85 :
86 : /* ----------------------------------------------------------------
87 : * macros used in index_ routines
88 : *
89 : * Note: the ReindexIsProcessingIndex() check in RELATION_CHECKS is there
90 : * to check that we don't try to scan or do retail insertions into an index
91 : * that is currently being rebuilt or pending rebuild. This helps to catch
92 : * things that don't work when reindexing system catalogs. The assertion
93 : * doesn't prevent the actual rebuild because we don't use RELATION_CHECKS
94 : * when calling the index AM's ambuild routine, and there is no reason for
95 : * ambuild to call its subsidiary routines through this file.
96 : * ----------------------------------------------------------------
97 : */
98 : #define RELATION_CHECKS \
99 : ( \
100 : AssertMacro(RelationIsValid(indexRelation)), \
101 : AssertMacro(PointerIsValid(indexRelation->rd_amroutine)), \
102 : AssertMacro(!ReindexIsProcessingIndex(RelationGetRelid(indexRelation))) \
103 : )
104 :
105 : #define SCAN_CHECKS \
106 : ( \
107 : AssertMacro(IndexScanIsValid(scan)), \
108 : AssertMacro(RelationIsValid(scan->indexRelation)), \
109 : AssertMacro(PointerIsValid(scan->indexRelation->rd_amroutine)) \
110 : )
111 :
112 : #define CHECK_REL_PROCEDURE(pname) \
113 : do { \
114 : if (indexRelation->rd_amroutine->pname == NULL) \
115 : elog(ERROR, "function %s is not defined for index %s", \
116 : CppAsString(pname), RelationGetRelationName(indexRelation)); \
117 : } while(0)
118 :
119 : #define CHECK_SCAN_PROCEDURE(pname) \
120 : do { \
121 : if (scan->indexRelation->rd_amroutine->pname == NULL) \
122 : elog(ERROR, "function %s is not defined for index %s", \
123 : CppAsString(pname), RelationGetRelationName(scan->indexRelation)); \
124 : } while(0)
125 :
126 : static IndexScanDesc index_beginscan_internal(Relation indexRelation,
127 : int nkeys, int norderbys, Snapshot snapshot,
128 : ParallelIndexScanDesc pscan, bool temp_snap);
129 :
130 :
131 : /* ----------------------------------------------------------------
132 : * index_ interface functions
133 : * ----------------------------------------------------------------
134 : */
135 :
136 : /* ----------------
137 : * index_open - open an index relation by relation OID
138 : *
139 : * If lockmode is not "NoLock", the specified kind of lock is
140 : * obtained on the index. (Generally, NoLock should only be
141 : * used if the caller knows it has some appropriate lock on the
142 : * index already.)
143 : *
144 : * An error is raised if the index does not exist.
145 : *
146 : * This is a convenience routine adapted for indexscan use.
147 : * Some callers may prefer to use relation_open directly.
148 : * ----------------
149 : */
150 : Relation
151 489249 : index_open(Oid relationId, LOCKMODE lockmode)
152 : {
153 : Relation r;
154 :
155 489249 : r = relation_open(relationId, lockmode);
156 :
157 489249 : if (r->rd_rel->relkind != RELKIND_INDEX)
158 1 : ereport(ERROR,
159 : (errcode(ERRCODE_WRONG_OBJECT_TYPE),
160 : errmsg("\"%s\" is not an index",
161 : RelationGetRelationName(r))));
162 :
163 489248 : return r;
164 : }
165 :
166 : /* ----------------
167 : * index_close - close an index relation
168 : *
169 : * If lockmode is not "NoLock", we then release the specified lock.
170 : *
171 : * Note that it is often sensible to hold a lock beyond index_close;
172 : * in that case, the lock is released automatically at xact end.
173 : * ----------------
174 : */
175 : void
176 490341 : index_close(Relation relation, LOCKMODE lockmode)
177 : {
178 490341 : LockRelId relid = relation->rd_lockInfo.lockRelId;
179 :
180 490341 : Assert(lockmode >= NoLock && lockmode < MAX_LOCKMODES);
181 :
182 : /* The relcache does the real work... */
183 490341 : RelationClose(relation);
184 :
185 490341 : if (lockmode != NoLock)
186 455811 : UnlockRelationId(&relid, lockmode);
187 490341 : }
188 :
189 : /* ----------------
190 : * index_insert - insert an index tuple into a relation
191 : * ----------------
192 : */
193 : bool
194 323823 : index_insert(Relation indexRelation,
195 : Datum *values,
196 : bool *isnull,
197 : ItemPointer heap_t_ctid,
198 : Relation heapRelation,
199 : IndexUniqueCheck checkUnique,
200 : IndexInfo *indexInfo)
201 : {
202 323823 : RELATION_CHECKS;
203 323823 : CHECK_REL_PROCEDURE(aminsert);
204 :
205 323823 : if (!(indexRelation->rd_amroutine->ampredlocks))
206 117814 : CheckForSerializableConflictIn(indexRelation,
207 : (HeapTuple) NULL,
208 : InvalidBuffer);
209 :
210 323823 : return indexRelation->rd_amroutine->aminsert(indexRelation, values, isnull,
211 : heap_t_ctid, heapRelation,
212 : checkUnique, indexInfo);
213 : }
214 :
215 : /*
216 : * index_beginscan - start a scan of an index with amgettuple
217 : *
218 : * Caller must be holding suitable locks on the heap and the index.
219 : */
220 : IndexScanDesc
221 363118 : index_beginscan(Relation heapRelation,
222 : Relation indexRelation,
223 : Snapshot snapshot,
224 : int nkeys, int norderbys)
225 : {
226 : IndexScanDesc scan;
227 :
228 363118 : scan = index_beginscan_internal(indexRelation, nkeys, norderbys, snapshot, NULL, false);
229 :
230 : /*
231 : * Save additional parameters into the scandesc. Everything else was set
232 : * up by RelationGetIndexScan.
233 : */
234 363118 : scan->heapRelation = heapRelation;
235 363118 : scan->xs_snapshot = snapshot;
236 :
237 363118 : return scan;
238 : }
239 :
240 : /*
241 : * index_beginscan_bitmap - start a scan of an index with amgetbitmap
242 : *
243 : * As above, caller had better be holding some lock on the parent heap
244 : * relation, even though it's not explicitly mentioned here.
245 : */
246 : IndexScanDesc
247 1330 : index_beginscan_bitmap(Relation indexRelation,
248 : Snapshot snapshot,
249 : int nkeys)
250 : {
251 : IndexScanDesc scan;
252 :
253 1330 : scan = index_beginscan_internal(indexRelation, nkeys, 0, snapshot, NULL, false);
254 :
255 : /*
256 : * Save additional parameters into the scandesc. Everything else was set
257 : * up by RelationGetIndexScan.
258 : */
259 1330 : scan->xs_snapshot = snapshot;
260 :
261 1330 : return scan;
262 : }
263 :
264 : /*
265 : * index_beginscan_internal --- common code for index_beginscan variants
266 : */
267 : static IndexScanDesc
268 364489 : index_beginscan_internal(Relation indexRelation,
269 : int nkeys, int norderbys, Snapshot snapshot,
270 : ParallelIndexScanDesc pscan, bool temp_snap)
271 : {
272 : IndexScanDesc scan;
273 :
274 364489 : RELATION_CHECKS;
275 364489 : CHECK_REL_PROCEDURE(ambeginscan);
276 :
277 364489 : if (!(indexRelation->rd_amroutine->ampredlocks))
278 575 : PredicateLockRelation(indexRelation, snapshot);
279 :
280 : /*
281 : * We hold a reference count to the relcache entry throughout the scan.
282 : */
283 364489 : RelationIncrementReferenceCount(indexRelation);
284 :
285 : /*
286 : * Tell the AM to open a scan.
287 : */
288 364489 : scan = indexRelation->rd_amroutine->ambeginscan(indexRelation, nkeys,
289 : norderbys);
290 : /* Initialize information for parallel scan. */
291 364489 : scan->parallel_scan = pscan;
292 364489 : scan->xs_temp_snap = temp_snap;
293 :
294 364489 : return scan;
295 : }
296 :
297 : /* ----------------
298 : * index_rescan - (re)start a scan of an index
299 : *
300 : * During a restart, the caller may specify a new set of scankeys and/or
301 : * orderbykeys; but the number of keys cannot differ from what index_beginscan
302 : * was told. (Later we might relax that to "must not exceed", but currently
303 : * the index AMs tend to assume that scan->numberOfKeys is what to believe.)
304 : * To restart the scan without changing keys, pass NULL for the key arrays.
305 : * (Of course, keys *must* be passed on the first call, unless
306 : * scan->numberOfKeys is zero.)
307 : * ----------------
308 : */
309 : void
310 390529 : index_rescan(IndexScanDesc scan,
311 : ScanKey keys, int nkeys,
312 : ScanKey orderbys, int norderbys)
313 : {
314 390529 : SCAN_CHECKS;
315 390529 : CHECK_SCAN_PROCEDURE(amrescan);
316 :
317 390529 : Assert(nkeys == scan->numberOfKeys);
318 390529 : Assert(norderbys == scan->numberOfOrderBys);
319 :
320 : /* Release any held pin on a heap page */
321 390529 : if (BufferIsValid(scan->xs_cbuf))
322 : {
323 2439 : ReleaseBuffer(scan->xs_cbuf);
324 2439 : scan->xs_cbuf = InvalidBuffer;
325 : }
326 :
327 390529 : scan->xs_continue_hot = false;
328 :
329 390529 : scan->kill_prior_tuple = false; /* for safety */
330 :
331 390529 : scan->indexRelation->rd_amroutine->amrescan(scan, keys, nkeys,
332 : orderbys, norderbys);
333 390529 : }
334 :
335 : /* ----------------
336 : * index_endscan - end a scan
337 : * ----------------
338 : */
339 : void
340 364381 : index_endscan(IndexScanDesc scan)
341 : {
342 364381 : SCAN_CHECKS;
343 364381 : CHECK_SCAN_PROCEDURE(amendscan);
344 :
345 : /* Release any held pin on a heap page */
346 364381 : if (BufferIsValid(scan->xs_cbuf))
347 : {
348 193622 : ReleaseBuffer(scan->xs_cbuf);
349 193622 : scan->xs_cbuf = InvalidBuffer;
350 : }
351 :
352 : /* End the AM's scan */
353 364381 : scan->indexRelation->rd_amroutine->amendscan(scan);
354 :
355 : /* Release index refcount acquired by index_beginscan */
356 364381 : RelationDecrementReferenceCount(scan->indexRelation);
357 :
358 364381 : if (scan->xs_temp_snap)
359 41 : UnregisterSnapshot(scan->xs_snapshot);
360 :
361 : /* Release the scan data structure itself */
362 364381 : IndexScanEnd(scan);
363 364381 : }
364 :
365 : /* ----------------
366 : * index_markpos - mark a scan position
367 : * ----------------
368 : */
369 : void
370 21001 : index_markpos(IndexScanDesc scan)
371 : {
372 21001 : SCAN_CHECKS;
373 21001 : CHECK_SCAN_PROCEDURE(ammarkpos);
374 :
375 21001 : scan->indexRelation->rd_amroutine->ammarkpos(scan);
376 21001 : }
377 :
378 : /* ----------------
379 : * index_restrpos - restore a scan position
380 : *
381 : * NOTE: this only restores the internal scan state of the index AM.
382 : * The current result tuple (scan->xs_ctup) doesn't change. See comments
383 : * for ExecRestrPos().
384 : *
385 : * NOTE: in the presence of HOT chains, mark/restore only works correctly
386 : * if the scan's snapshot is MVCC-safe; that ensures that there's at most one
387 : * returnable tuple in each HOT chain, and so restoring the prior state at the
388 : * granularity of the index AM is sufficient. Since the only current user
389 : * of mark/restore functionality is nodeMergejoin.c, this effectively means
390 : * that merge-join plans only work for MVCC snapshots. This could be fixed
391 : * if necessary, but for now it seems unimportant.
392 : * ----------------
393 : */
394 : void
395 9001 : index_restrpos(IndexScanDesc scan)
396 : {
397 9001 : Assert(IsMVCCSnapshot(scan->xs_snapshot));
398 :
399 9001 : SCAN_CHECKS;
400 9001 : CHECK_SCAN_PROCEDURE(amrestrpos);
401 :
402 9001 : scan->xs_continue_hot = false;
403 :
404 9001 : scan->kill_prior_tuple = false; /* for safety */
405 :
406 9001 : scan->indexRelation->rd_amroutine->amrestrpos(scan);
407 9001 : }
408 :
409 : /*
410 : * index_parallelscan_estimate - estimate shared memory for parallel scan
411 : *
412 : * Currently, we don't pass any information to the AM-specific estimator,
413 : * so it can probably only return a constant. In the future, we might need
414 : * to pass more information.
415 : */
416 : Size
417 5 : index_parallelscan_estimate(Relation indexRelation, Snapshot snapshot)
418 : {
419 : Size nbytes;
420 :
421 5 : RELATION_CHECKS;
422 :
423 5 : nbytes = offsetof(ParallelIndexScanDescData, ps_snapshot_data);
424 5 : nbytes = add_size(nbytes, EstimateSnapshotSpace(snapshot));
425 5 : nbytes = MAXALIGN(nbytes);
426 :
427 : /*
428 : * If amestimateparallelscan is not provided, assume there is no
429 : * AM-specific data needed. (It's hard to believe that could work, but
430 : * it's easy enough to cater to it here.)
431 : */
432 5 : if (indexRelation->rd_amroutine->amestimateparallelscan != NULL)
433 5 : nbytes = add_size(nbytes,
434 5 : indexRelation->rd_amroutine->amestimateparallelscan());
435 :
436 5 : return nbytes;
437 : }
438 :
439 : /*
440 : * index_parallelscan_initialize - initialize parallel scan
441 : *
442 : * We initialize both the ParallelIndexScanDesc proper and the AM-specific
443 : * information which follows it.
444 : *
445 : * This function calls access method specific initialization routine to
446 : * initialize am specific information. Call this just once in the leader
447 : * process; then, individual workers attach via index_beginscan_parallel.
448 : */
449 : void
450 5 : index_parallelscan_initialize(Relation heapRelation, Relation indexRelation,
451 : Snapshot snapshot, ParallelIndexScanDesc target)
452 : {
453 : Size offset;
454 :
455 5 : RELATION_CHECKS;
456 :
457 5 : offset = add_size(offsetof(ParallelIndexScanDescData, ps_snapshot_data),
458 : EstimateSnapshotSpace(snapshot));
459 5 : offset = MAXALIGN(offset);
460 :
461 5 : target->ps_relid = RelationGetRelid(heapRelation);
462 5 : target->ps_indexid = RelationGetRelid(indexRelation);
463 5 : target->ps_offset = offset;
464 5 : SerializeSnapshot(snapshot, target->ps_snapshot_data);
465 :
466 : /* aminitparallelscan is optional; assume no-op if not provided by AM */
467 5 : if (indexRelation->rd_amroutine->aminitparallelscan != NULL)
468 : {
469 : void *amtarget;
470 :
471 5 : amtarget = OffsetToPointer(target, offset);
472 5 : indexRelation->rd_amroutine->aminitparallelscan(amtarget);
473 : }
474 5 : }
475 :
476 : /* ----------------
477 : * index_parallelrescan - (re)start a parallel scan of an index
478 : * ----------------
479 : */
480 : void
481 4 : index_parallelrescan(IndexScanDesc scan)
482 : {
483 4 : SCAN_CHECKS;
484 :
485 : /* amparallelrescan is optional; assume no-op if not provided by AM */
486 4 : if (scan->indexRelation->rd_amroutine->amparallelrescan != NULL)
487 4 : scan->indexRelation->rd_amroutine->amparallelrescan(scan);
488 4 : }
489 :
490 : /*
491 : * index_beginscan_parallel - join parallel index scan
492 : *
493 : * Caller must be holding suitable locks on the heap and the index.
494 : */
495 : IndexScanDesc
496 41 : index_beginscan_parallel(Relation heaprel, Relation indexrel, int nkeys,
497 : int norderbys, ParallelIndexScanDesc pscan)
498 : {
499 : Snapshot snapshot;
500 : IndexScanDesc scan;
501 :
502 41 : Assert(RelationGetRelid(heaprel) == pscan->ps_relid);
503 41 : snapshot = RestoreSnapshot(pscan->ps_snapshot_data);
504 41 : RegisterSnapshot(snapshot);
505 41 : scan = index_beginscan_internal(indexrel, nkeys, norderbys, snapshot,
506 : pscan, true);
507 :
508 : /*
509 : * Save additional parameters into the scandesc. Everything else was set
510 : * up by index_beginscan_internal.
511 : */
512 41 : scan->heapRelation = heaprel;
513 41 : scan->xs_snapshot = snapshot;
514 :
515 41 : return scan;
516 : }
517 :
518 : /* ----------------
519 : * index_getnext_tid - get the next TID from a scan
520 : *
521 : * The result is the next TID satisfying the scan keys,
522 : * or NULL if no more matching tuples exist.
523 : * ----------------
524 : */
525 : ItemPointer
526 1338068 : index_getnext_tid(IndexScanDesc scan, ScanDirection direction)
527 : {
528 : bool found;
529 :
530 1338068 : SCAN_CHECKS;
531 1338068 : CHECK_SCAN_PROCEDURE(amgettuple);
532 :
533 1338068 : Assert(TransactionIdIsValid(RecentGlobalXmin));
534 :
535 : /*
536 : * The AM's amgettuple proc finds the next index entry matching the scan
537 : * keys, and puts the TID into scan->xs_ctup.t_self. It should also set
538 : * scan->xs_recheck and possibly scan->xs_itup/scan->xs_hitup, though we
539 : * pay no attention to those fields here.
540 : */
541 1338068 : found = scan->indexRelation->rd_amroutine->amgettuple(scan, direction);
542 :
543 : /* Reset kill flag immediately for safety */
544 1338068 : scan->kill_prior_tuple = false;
545 :
546 : /* If we're out of index entries, we're done */
547 1338068 : if (!found)
548 : {
549 : /* ... but first, release any held pin on a heap page */
550 191775 : if (BufferIsValid(scan->xs_cbuf))
551 : {
552 78015 : ReleaseBuffer(scan->xs_cbuf);
553 78015 : scan->xs_cbuf = InvalidBuffer;
554 : }
555 191775 : return NULL;
556 : }
557 :
558 1146293 : pgstat_count_index_tuples(scan->indexRelation, 1);
559 :
560 : /* Return the TID of the tuple we found. */
561 1146293 : return &scan->xs_ctup.t_self;
562 : }
563 :
564 : /* ----------------
565 : * index_fetch_heap - get the scan's next heap tuple
566 : *
567 : * The result is a visible heap tuple associated with the index TID most
568 : * recently fetched by index_getnext_tid, or NULL if no more matching tuples
569 : * exist. (There can be more than one matching tuple because of HOT chains,
570 : * although when using an MVCC snapshot it should be impossible for more than
571 : * one such tuple to exist.)
572 : *
573 : * On success, the buffer containing the heap tup is pinned (the pin will be
574 : * dropped in a future index_getnext_tid, index_fetch_heap or index_endscan
575 : * call).
576 : *
577 : * Note: caller must check scan->xs_recheck, and perform rechecking of the
578 : * scan keys if required. We do not do that here because we don't have
579 : * enough information to do it efficiently in the general case.
580 : * ----------------
581 : */
582 : HeapTuple
583 706933 : index_fetch_heap(IndexScanDesc scan)
584 : {
585 706933 : ItemPointer tid = &scan->xs_ctup.t_self;
586 706933 : bool all_dead = false;
587 : bool got_heap_tuple;
588 :
589 : /* We can skip the buffer-switching logic if we're in mid-HOT chain. */
590 706933 : if (!scan->xs_continue_hot)
591 : {
592 : /* Switch to correct buffer if we don't have it already */
593 705249 : Buffer prev_buf = scan->xs_cbuf;
594 :
595 705249 : scan->xs_cbuf = ReleaseAndReadBuffer(scan->xs_cbuf,
596 : scan->heapRelation,
597 705249 : ItemPointerGetBlockNumber(tid));
598 :
599 : /*
600 : * Prune page, but only if we weren't already on this page
601 : */
602 705249 : if (prev_buf != scan->xs_cbuf)
603 371088 : heap_page_prune_opt(scan->heapRelation, scan->xs_cbuf);
604 : }
605 :
606 : /* Obtain share-lock on the buffer so we can examine visibility */
607 706933 : LockBuffer(scan->xs_cbuf, BUFFER_LOCK_SHARE);
608 706933 : got_heap_tuple = heap_hot_search_buffer(tid, scan->heapRelation,
609 : scan->xs_cbuf,
610 : scan->xs_snapshot,
611 : &scan->xs_ctup,
612 : &all_dead,
613 706933 : !scan->xs_continue_hot);
614 706933 : LockBuffer(scan->xs_cbuf, BUFFER_LOCK_UNLOCK);
615 :
616 706933 : if (got_heap_tuple)
617 : {
618 : /*
619 : * Only in a non-MVCC snapshot can more than one member of the HOT
620 : * chain be visible.
621 : */
622 683446 : scan->xs_continue_hot = !IsMVCCSnapshot(scan->xs_snapshot);
623 683446 : pgstat_count_heap_fetch(scan->indexRelation);
624 683446 : return &scan->xs_ctup;
625 : }
626 :
627 : /* We've reached the end of the HOT chain. */
628 23487 : scan->xs_continue_hot = false;
629 :
630 : /*
631 : * If we scanned a whole HOT chain and found only dead tuples, tell index
632 : * AM to kill its entry for that TID (this will take effect in the next
633 : * amgettuple call, in index_getnext_tid). We do not do this when in
634 : * recovery because it may violate MVCC to do so. See comments in
635 : * RelationGetIndexScan().
636 : */
637 23487 : if (!scan->xactStartedInRecovery)
638 23487 : scan->kill_prior_tuple = all_dead;
639 :
640 23487 : return NULL;
641 : }
642 :
643 : /* ----------------
644 : * index_getnext - get the next heap tuple from a scan
645 : *
646 : * The result is the next heap tuple satisfying the scan keys and the
647 : * snapshot, or NULL if no more matching tuples exist.
648 : *
649 : * On success, the buffer containing the heap tup is pinned (the pin will be
650 : * dropped in a future index_getnext_tid, index_fetch_heap or index_endscan
651 : * call).
652 : *
653 : * Note: caller must check scan->xs_recheck, and perform rechecking of the
654 : * scan keys if required. We do not do that here because we don't have
655 : * enough information to do it efficiently in the general case.
656 : * ----------------
657 : */
658 : HeapTuple
659 750454 : index_getnext(IndexScanDesc scan, ScanDirection direction)
660 : {
661 : HeapTuple heapTuple;
662 : ItemPointer tid;
663 :
664 : for (;;)
665 : {
666 750454 : if (scan->xs_continue_hot)
667 : {
668 : /*
669 : * We are resuming scan of a HOT chain after having returned an
670 : * earlier member. Must still hold pin on current heap page.
671 : */
672 1684 : Assert(BufferIsValid(scan->xs_cbuf));
673 1684 : Assert(ItemPointerGetBlockNumber(&scan->xs_ctup.t_self) ==
674 : BufferGetBlockNumber(scan->xs_cbuf));
675 : }
676 : else
677 : {
678 : /* Time to fetch the next TID from the index */
679 748770 : tid = index_getnext_tid(scan, direction);
680 :
681 : /* If we're out of index entries, we're done */
682 748770 : if (tid == NULL)
683 190797 : break;
684 : }
685 :
686 : /*
687 : * Fetch the next (or only) visible heap tuple for this index entry.
688 : * If we don't find anything, loop around and grab the next TID from
689 : * the index.
690 : */
691 559657 : heapTuple = index_fetch_heap(scan);
692 559657 : if (heapTuple != NULL)
693 536209 : return heapTuple;
694 23448 : }
695 :
696 190797 : return NULL; /* failure exit */
697 : }
698 :
699 : /* ----------------
700 : * index_getbitmap - get all tuples at once from an index scan
701 : *
702 : * Adds the TIDs of all heap tuples satisfying the scan keys to a bitmap.
703 : * Since there's no interlock between the index scan and the eventual heap
704 : * access, this is only safe to use with MVCC-based snapshots: the heap
705 : * item slot could have been replaced by a newer tuple by the time we get
706 : * to it.
707 : *
708 : * Returns the number of matching tuples found. (Note: this might be only
709 : * approximate, so it should only be used for statistical purposes.)
710 : * ----------------
711 : */
712 : int64
713 1115 : index_getbitmap(IndexScanDesc scan, TIDBitmap *bitmap)
714 : {
715 : int64 ntids;
716 :
717 1115 : SCAN_CHECKS;
718 1115 : CHECK_SCAN_PROCEDURE(amgetbitmap);
719 :
720 : /* just make sure this is false... */
721 1115 : scan->kill_prior_tuple = false;
722 :
723 : /*
724 : * have the am's getbitmap proc do all the work.
725 : */
726 1115 : ntids = scan->indexRelation->rd_amroutine->amgetbitmap(scan, bitmap);
727 :
728 1115 : pgstat_count_index_tuples(scan->indexRelation, ntids);
729 :
730 1115 : return ntids;
731 : }
732 :
733 : /* ----------------
734 : * index_bulk_delete - do mass deletion of index entries
735 : *
736 : * callback routine tells whether a given main-heap tuple is
737 : * to be deleted
738 : *
739 : * return value is an optional palloc'd struct of statistics
740 : * ----------------
741 : */
742 : IndexBulkDeleteResult *
743 134 : index_bulk_delete(IndexVacuumInfo *info,
744 : IndexBulkDeleteResult *stats,
745 : IndexBulkDeleteCallback callback,
746 : void *callback_state)
747 : {
748 134 : Relation indexRelation = info->index;
749 :
750 134 : RELATION_CHECKS;
751 134 : CHECK_REL_PROCEDURE(ambulkdelete);
752 :
753 134 : return indexRelation->rd_amroutine->ambulkdelete(info, stats,
754 : callback, callback_state);
755 : }
756 :
757 : /* ----------------
758 : * index_vacuum_cleanup - do post-deletion cleanup of an index
759 : *
760 : * return value is an optional palloc'd struct of statistics
761 : * ----------------
762 : */
763 : IndexBulkDeleteResult *
764 640 : index_vacuum_cleanup(IndexVacuumInfo *info,
765 : IndexBulkDeleteResult *stats)
766 : {
767 640 : Relation indexRelation = info->index;
768 :
769 640 : RELATION_CHECKS;
770 640 : CHECK_REL_PROCEDURE(amvacuumcleanup);
771 :
772 640 : return indexRelation->rd_amroutine->amvacuumcleanup(info, stats);
773 : }
774 :
775 : /* ----------------
776 : * index_can_return
777 : *
778 : * Does the index access method support index-only scans for the given
779 : * column?
780 : * ----------------
781 : */
782 : bool
783 61642 : index_can_return(Relation indexRelation, int attno)
784 : {
785 61642 : RELATION_CHECKS;
786 :
787 : /* amcanreturn is optional; assume FALSE if not provided by AM */
788 61642 : if (indexRelation->rd_amroutine->amcanreturn == NULL)
789 30011 : return false;
790 :
791 31631 : return indexRelation->rd_amroutine->amcanreturn(indexRelation, attno);
792 : }
793 :
794 : /* ----------------
795 : * index_getprocid
796 : *
797 : * Index access methods typically require support routines that are
798 : * not directly the implementation of any WHERE-clause query operator
799 : * and so cannot be kept in pg_amop. Instead, such routines are kept
800 : * in pg_amproc. These registered procedure OIDs are assigned numbers
801 : * according to a convention established by the access method.
802 : * The general index code doesn't know anything about the routines
803 : * involved; it just builds an ordered list of them for
804 : * each attribute on which an index is defined.
805 : *
806 : * As of Postgres 8.3, support routines within an operator family
807 : * are further subdivided by the "left type" and "right type" of the
808 : * query operator(s) that they support. The "default" functions for a
809 : * particular indexed attribute are those with both types equal to
810 : * the index opclass' opcintype (note that this is subtly different
811 : * from the indexed attribute's own type: it may be a binary-compatible
812 : * type instead). Only the default functions are stored in relcache
813 : * entries --- access methods can use the syscache to look up non-default
814 : * functions.
815 : *
816 : * This routine returns the requested default procedure OID for a
817 : * particular indexed attribute.
818 : * ----------------
819 : */
820 : RegProcedure
821 1091 : index_getprocid(Relation irel,
822 : AttrNumber attnum,
823 : uint16 procnum)
824 : {
825 : RegProcedure *loc;
826 : int nproc;
827 : int procindex;
828 :
829 1091 : nproc = irel->rd_amroutine->amsupport;
830 :
831 1091 : Assert(procnum > 0 && procnum <= (uint16) nproc);
832 :
833 1091 : procindex = (nproc * (attnum - 1)) + (procnum - 1);
834 :
835 1091 : loc = irel->rd_support;
836 :
837 1091 : Assert(loc != NULL);
838 :
839 1091 : return loc[procindex];
840 : }
841 :
842 : /* ----------------
843 : * index_getprocinfo
844 : *
845 : * This routine allows index AMs to keep fmgr lookup info for
846 : * support procs in the relcache. As above, only the "default"
847 : * functions for any particular indexed attribute are cached.
848 : *
849 : * Note: the return value points into cached data that will be lost during
850 : * any relcache rebuild! Therefore, either use the callinfo right away,
851 : * or save it only after having acquired some type of lock on the index rel.
852 : * ----------------
853 : */
854 : FmgrInfo *
855 1624503 : index_getprocinfo(Relation irel,
856 : AttrNumber attnum,
857 : uint16 procnum)
858 : {
859 : FmgrInfo *locinfo;
860 : int nproc;
861 : int procindex;
862 :
863 1624503 : nproc = irel->rd_amroutine->amsupport;
864 :
865 1624503 : Assert(procnum > 0 && procnum <= (uint16) nproc);
866 :
867 1624503 : procindex = (nproc * (attnum - 1)) + (procnum - 1);
868 :
869 1624503 : locinfo = irel->rd_supportinfo;
870 :
871 1624503 : Assert(locinfo != NULL);
872 :
873 1624503 : locinfo += procindex;
874 :
875 : /* Initialize the lookup info if first time through */
876 1624503 : if (locinfo->fn_oid == InvalidOid)
877 : {
878 21763 : RegProcedure *loc = irel->rd_support;
879 : RegProcedure procId;
880 :
881 21763 : Assert(loc != NULL);
882 :
883 21763 : procId = loc[procindex];
884 :
885 : /*
886 : * Complain if function was not found during IndexSupportInitialize.
887 : * This should not happen unless the system tables contain bogus
888 : * entries for the index opclass. (If an AM wants to allow a support
889 : * function to be optional, it can use index_getprocid.)
890 : */
891 21763 : if (!RegProcedureIsValid(procId))
892 0 : elog(ERROR, "missing support function %d for attribute %d of index \"%s\"",
893 : procnum, attnum, RelationGetRelationName(irel));
894 :
895 21763 : fmgr_info_cxt(procId, locinfo, irel->rd_indexcxt);
896 : }
897 :
898 1624503 : return locinfo;
899 : }
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