Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * gistget.c
4 : * fetch tuples from a GiST scan.
5 : *
6 : *
7 : * Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
8 : * Portions Copyright (c) 1994, Regents of the University of California
9 : *
10 : * IDENTIFICATION
11 : * src/backend/access/gist/gistget.c
12 : *
13 : *-------------------------------------------------------------------------
14 : */
15 : #include "postgres.h"
16 :
17 : #include "access/genam.h"
18 : #include "access/gist_private.h"
19 : #include "access/relscan.h"
20 : #include "lib/pairingheap.h"
21 : #include "miscadmin.h"
22 : #include "pgstat.h"
23 : #include "storage/predicate.h"
24 : #include "utils/float.h"
25 : #include "utils/memutils.h"
26 : #include "utils/rel.h"
27 :
28 : /*
29 : * gistkillitems() -- set LP_DEAD state for items an indexscan caller has
30 : * told us were killed.
31 : *
32 : * We re-read page here, so it's important to check page LSN. If the page
33 : * has been modified since the last read (as determined by LSN), we cannot
34 : * flag any entries because it is possible that the old entry was vacuumed
35 : * away and the TID was re-used by a completely different heap tuple.
36 : */
37 : static void
38 0 : gistkillitems(IndexScanDesc scan)
39 : {
40 0 : GISTScanOpaque so = (GISTScanOpaque) scan->opaque;
41 : Buffer buffer;
42 : Page page;
43 : OffsetNumber offnum;
44 : ItemId iid;
45 : int i;
46 0 : bool killedsomething = false;
47 :
48 : Assert(so->curBlkno != InvalidBlockNumber);
49 : Assert(!XLogRecPtrIsInvalid(so->curPageLSN));
50 : Assert(so->killedItems != NULL);
51 :
52 0 : buffer = ReadBuffer(scan->indexRelation, so->curBlkno);
53 0 : if (!BufferIsValid(buffer))
54 0 : return;
55 :
56 0 : LockBuffer(buffer, GIST_SHARE);
57 0 : gistcheckpage(scan->indexRelation, buffer);
58 0 : page = BufferGetPage(buffer);
59 :
60 : /*
61 : * If page LSN differs it means that the page was modified since the last
62 : * read. killedItems could be not valid so LP_DEAD hints applying is not
63 : * safe.
64 : */
65 0 : if (BufferGetLSNAtomic(buffer) != so->curPageLSN)
66 : {
67 0 : UnlockReleaseBuffer(buffer);
68 0 : so->numKilled = 0; /* reset counter */
69 0 : return;
70 : }
71 :
72 : Assert(GistPageIsLeaf(page));
73 :
74 : /*
75 : * Mark all killedItems as dead. We need no additional recheck, because,
76 : * if page was modified, curPageLSN must have changed.
77 : */
78 0 : for (i = 0; i < so->numKilled; i++)
79 : {
80 0 : offnum = so->killedItems[i];
81 0 : iid = PageGetItemId(page, offnum);
82 0 : ItemIdMarkDead(iid);
83 0 : killedsomething = true;
84 : }
85 :
86 0 : if (killedsomething)
87 : {
88 0 : GistMarkPageHasGarbage(page);
89 0 : MarkBufferDirtyHint(buffer, true);
90 : }
91 :
92 0 : UnlockReleaseBuffer(buffer);
93 :
94 : /*
95 : * Always reset the scan state, so we don't look for same items on other
96 : * pages.
97 : */
98 0 : so->numKilled = 0;
99 : }
100 :
101 : /*
102 : * gistindex_keytest() -- does this index tuple satisfy the scan key(s)?
103 : *
104 : * The index tuple might represent either a heap tuple or a lower index page,
105 : * depending on whether the containing page is a leaf page or not.
106 : *
107 : * On success return for a heap tuple, *recheck_p is set to indicate whether
108 : * the quals need to be rechecked. We recheck if any of the consistent()
109 : * functions request it. recheck is not interesting when examining a non-leaf
110 : * entry, since we must visit the lower index page if there's any doubt.
111 : * Similarly, *recheck_distances_p is set to indicate whether the distances
112 : * need to be rechecked, and it is also ignored for non-leaf entries.
113 : *
114 : * If we are doing an ordered scan, so->distances[] is filled with distance
115 : * data from the distance() functions before returning success.
116 : *
117 : * We must decompress the key in the IndexTuple before passing it to the
118 : * sk_funcs (which actually are the opclass Consistent or Distance methods).
119 : *
120 : * Note that this function is always invoked in a short-lived memory context,
121 : * so we don't need to worry about cleaning up allocated memory, either here
122 : * or in the implementation of any Consistent or Distance methods.
123 : */
124 : static bool
125 2137874 : gistindex_keytest(IndexScanDesc scan,
126 : IndexTuple tuple,
127 : Page page,
128 : OffsetNumber offset,
129 : bool *recheck_p,
130 : bool *recheck_distances_p)
131 : {
132 2137874 : GISTScanOpaque so = (GISTScanOpaque) scan->opaque;
133 2137874 : GISTSTATE *giststate = so->giststate;
134 2137874 : ScanKey key = scan->keyData;
135 2137874 : int keySize = scan->numberOfKeys;
136 : IndexOrderByDistance *distance_p;
137 2137874 : Relation r = scan->indexRelation;
138 :
139 2137874 : *recheck_p = false;
140 2137874 : *recheck_distances_p = false;
141 :
142 : /*
143 : * If it's a leftover invalid tuple from pre-9.1, treat it as a match with
144 : * minimum possible distances. This means we'll always follow it to the
145 : * referenced page.
146 : */
147 2137874 : if (GistTupleIsInvalid(tuple))
148 : {
149 : int i;
150 :
151 0 : if (GistPageIsLeaf(page)) /* shouldn't happen */
152 0 : elog(ERROR, "invalid GiST tuple found on leaf page");
153 0 : for (i = 0; i < scan->numberOfOrderBys; i++)
154 : {
155 0 : so->distances[i].value = -get_float8_infinity();
156 0 : so->distances[i].isnull = false;
157 : }
158 0 : return true;
159 : }
160 :
161 : /* Check whether it matches according to the Consistent functions */
162 3300086 : while (keySize > 0)
163 : {
164 : Datum datum;
165 : bool isNull;
166 :
167 2054372 : datum = index_getattr(tuple,
168 2054372 : key->sk_attno,
169 : giststate->leafTupdesc,
170 : &isNull);
171 :
172 2054372 : if (key->sk_flags & SK_ISNULL)
173 : {
174 : /*
175 : * On non-leaf page we can't conclude that child hasn't NULL
176 : * values because of assumption in GiST: union (VAL, NULL) is VAL.
177 : * But if on non-leaf page key IS NULL, then all children are
178 : * NULL.
179 : */
180 46194 : if (key->sk_flags & SK_SEARCHNULL)
181 : {
182 46128 : if (GistPageIsLeaf(page) && !isNull)
183 892160 : return false;
184 : }
185 : else
186 : {
187 : Assert(key->sk_flags & SK_SEARCHNOTNULL);
188 66 : if (isNull)
189 6 : return false;
190 : }
191 : }
192 2008178 : else if (isNull)
193 : {
194 1302 : return false;
195 : }
196 : else
197 : {
198 : Datum test;
199 : bool recheck;
200 : GISTENTRY de;
201 :
202 2006876 : gistdentryinit(giststate, key->sk_attno - 1, &de,
203 : datum, r, page, offset,
204 : false, isNull);
205 :
206 : /*
207 : * Call the Consistent function to evaluate the test. The
208 : * arguments are the index datum (as a GISTENTRY*), the comparison
209 : * datum, the comparison operator's strategy number and subtype
210 : * from pg_amop, and the recheck flag.
211 : *
212 : * (Presently there's no need to pass the subtype since it'll
213 : * always be zero, but might as well pass it for possible future
214 : * use.)
215 : *
216 : * We initialize the recheck flag to true (the safest assumption)
217 : * in case the Consistent function forgets to set it.
218 : */
219 2006876 : recheck = true;
220 :
221 4013752 : test = FunctionCall5Coll(&key->sk_func,
222 : key->sk_collation,
223 : PointerGetDatum(&de),
224 : key->sk_argument,
225 2006876 : Int16GetDatum(key->sk_strategy),
226 : ObjectIdGetDatum(key->sk_subtype),
227 : PointerGetDatum(&recheck));
228 :
229 2006876 : if (!DatumGetBool(test))
230 848438 : return false;
231 1158438 : *recheck_p |= recheck;
232 : }
233 :
234 1162212 : key++;
235 1162212 : keySize--;
236 : }
237 :
238 : /* OK, it passes --- now let's compute the distances */
239 1245714 : key = scan->orderByData;
240 1245714 : distance_p = so->distances;
241 1245714 : keySize = scan->numberOfOrderBys;
242 1276382 : while (keySize > 0)
243 : {
244 : Datum datum;
245 : bool isNull;
246 :
247 30668 : datum = index_getattr(tuple,
248 30668 : key->sk_attno,
249 : giststate->leafTupdesc,
250 : &isNull);
251 :
252 30668 : if ((key->sk_flags & SK_ISNULL) || isNull)
253 : {
254 : /* Assume distance computes as null */
255 108 : distance_p->value = 0.0;
256 108 : distance_p->isnull = true;
257 : }
258 : else
259 : {
260 : Datum dist;
261 : bool recheck;
262 : GISTENTRY de;
263 :
264 30560 : gistdentryinit(giststate, key->sk_attno - 1, &de,
265 : datum, r, page, offset,
266 : false, isNull);
267 :
268 : /*
269 : * Call the Distance function to evaluate the distance. The
270 : * arguments are the index datum (as a GISTENTRY*), the comparison
271 : * datum, the ordering operator's strategy number and subtype from
272 : * pg_amop, and the recheck flag.
273 : *
274 : * (Presently there's no need to pass the subtype since it'll
275 : * always be zero, but might as well pass it for possible future
276 : * use.)
277 : *
278 : * If the function sets the recheck flag, the returned distance is
279 : * a lower bound on the true distance and needs to be rechecked.
280 : * We initialize the flag to 'false'. This flag was added in
281 : * version 9.5; distance functions written before that won't know
282 : * about the flag, but are expected to never be lossy.
283 : */
284 30560 : recheck = false;
285 61120 : dist = FunctionCall5Coll(&key->sk_func,
286 : key->sk_collation,
287 : PointerGetDatum(&de),
288 : key->sk_argument,
289 30560 : Int16GetDatum(key->sk_strategy),
290 : ObjectIdGetDatum(key->sk_subtype),
291 : PointerGetDatum(&recheck));
292 30560 : *recheck_distances_p |= recheck;
293 30560 : distance_p->value = DatumGetFloat8(dist);
294 30560 : distance_p->isnull = false;
295 : }
296 :
297 30668 : key++;
298 30668 : distance_p++;
299 30668 : keySize--;
300 : }
301 :
302 1245714 : return true;
303 : }
304 :
305 : /*
306 : * Scan all items on the GiST index page identified by *pageItem, and insert
307 : * them into the queue (or directly to output areas)
308 : *
309 : * scan: index scan we are executing
310 : * pageItem: search queue item identifying an index page to scan
311 : * myDistances: distances array associated with pageItem, or NULL at the root
312 : * tbm: if not NULL, gistgetbitmap's output bitmap
313 : * ntids: if not NULL, gistgetbitmap's output tuple counter
314 : *
315 : * If tbm/ntids aren't NULL, we are doing an amgetbitmap scan, and heap
316 : * tuples should be reported directly into the bitmap. If they are NULL,
317 : * we're doing a plain or ordered indexscan. For a plain indexscan, heap
318 : * tuple TIDs are returned into so->pageData[]. For an ordered indexscan,
319 : * heap tuple TIDs are pushed into individual search queue items. In an
320 : * index-only scan, reconstructed index tuples are returned along with the
321 : * TIDs.
322 : *
323 : * If we detect that the index page has split since we saw its downlink
324 : * in the parent, we push its new right sibling onto the queue so the
325 : * sibling will be processed next.
326 : */
327 : static void
328 78672 : gistScanPage(IndexScanDesc scan, GISTSearchItem *pageItem,
329 : IndexOrderByDistance *myDistances, TIDBitmap *tbm, int64 *ntids)
330 : {
331 78672 : GISTScanOpaque so = (GISTScanOpaque) scan->opaque;
332 78672 : GISTSTATE *giststate = so->giststate;
333 78672 : Relation r = scan->indexRelation;
334 : Buffer buffer;
335 : Page page;
336 : GISTPageOpaque opaque;
337 : OffsetNumber maxoff;
338 : OffsetNumber i;
339 : MemoryContext oldcxt;
340 :
341 : Assert(!GISTSearchItemIsHeap(*pageItem));
342 :
343 78672 : buffer = ReadBuffer(scan->indexRelation, pageItem->blkno);
344 78672 : LockBuffer(buffer, GIST_SHARE);
345 78672 : PredicateLockPage(r, BufferGetBlockNumber(buffer), scan->xs_snapshot);
346 78672 : gistcheckpage(scan->indexRelation, buffer);
347 78672 : page = BufferGetPage(buffer);
348 78672 : opaque = GistPageGetOpaque(page);
349 :
350 : /*
351 : * Check if we need to follow the rightlink. We need to follow it if the
352 : * page was concurrently split since we visited the parent (in which case
353 : * parentlsn < nsn), or if the system crashed after a page split but
354 : * before the downlink was inserted into the parent.
355 : */
356 78672 : if (!XLogRecPtrIsInvalid(pageItem->data.parentlsn) &&
357 144804 : (GistFollowRight(page) ||
358 72402 : pageItem->data.parentlsn < GistPageGetNSN(page)) &&
359 0 : opaque->rightlink != InvalidBlockNumber /* sanity check */ )
360 : {
361 : /* There was a page split, follow right link to add pages */
362 : GISTSearchItem *item;
363 :
364 : /* This can't happen when starting at the root */
365 : Assert(myDistances != NULL);
366 :
367 0 : oldcxt = MemoryContextSwitchTo(so->queueCxt);
368 :
369 : /* Create new GISTSearchItem for the right sibling index page */
370 0 : item = palloc(SizeOfGISTSearchItem(scan->numberOfOrderBys));
371 0 : item->blkno = opaque->rightlink;
372 0 : item->data.parentlsn = pageItem->data.parentlsn;
373 :
374 : /* Insert it into the queue using same distances as for this page */
375 0 : memcpy(item->distances, myDistances,
376 0 : sizeof(item->distances[0]) * scan->numberOfOrderBys);
377 :
378 0 : pairingheap_add(so->queue, &item->phNode);
379 :
380 0 : MemoryContextSwitchTo(oldcxt);
381 : }
382 :
383 : /*
384 : * Check if the page was deleted after we saw the downlink. There's
385 : * nothing of interest on a deleted page. Note that we must do this after
386 : * checking the NSN for concurrent splits! It's possible that the page
387 : * originally contained some tuples that are visible to us, but was split
388 : * so that all the visible tuples were moved to another page, and then
389 : * this page was deleted.
390 : */
391 78672 : if (GistPageIsDeleted(page))
392 : {
393 0 : UnlockReleaseBuffer(buffer);
394 0 : return;
395 : }
396 :
397 78672 : so->nPageData = so->curPageData = 0;
398 78672 : scan->xs_hitup = NULL; /* might point into pageDataCxt */
399 78672 : if (so->pageDataCxt)
400 6398 : MemoryContextReset(so->pageDataCxt);
401 :
402 : /*
403 : * We save the LSN of the page as we read it, so that we know whether it
404 : * safe to apply LP_DEAD hints to the page later. This allows us to drop
405 : * the pin for MVCC scans, which allows vacuum to avoid blocking.
406 : */
407 78672 : so->curPageLSN = BufferGetLSNAtomic(buffer);
408 :
409 : /*
410 : * check all tuples on page
411 : */
412 78672 : maxoff = PageGetMaxOffsetNumber(page);
413 2216546 : for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
414 : {
415 2137874 : ItemId iid = PageGetItemId(page, i);
416 : IndexTuple it;
417 : bool match;
418 : bool recheck;
419 : bool recheck_distances;
420 :
421 : /*
422 : * If the scan specifies not to return killed tuples, then we treat a
423 : * killed tuple as not passing the qual.
424 : */
425 2137874 : if (scan->ignore_killed_tuples && ItemIdIsDead(iid))
426 892160 : continue;
427 :
428 2137874 : it = (IndexTuple) PageGetItem(page, iid);
429 :
430 : /*
431 : * Must call gistindex_keytest in tempCxt, and clean up any leftover
432 : * junk afterward.
433 : */
434 2137874 : oldcxt = MemoryContextSwitchTo(so->giststate->tempCxt);
435 :
436 2137874 : match = gistindex_keytest(scan, it, page, i,
437 : &recheck, &recheck_distances);
438 :
439 2137874 : MemoryContextSwitchTo(oldcxt);
440 2137874 : MemoryContextReset(so->giststate->tempCxt);
441 :
442 : /* Ignore tuple if it doesn't match */
443 2137874 : if (!match)
444 892160 : continue;
445 :
446 1245714 : if (tbm && GistPageIsLeaf(page))
447 : {
448 : /*
449 : * getbitmap scan, so just push heap tuple TIDs into the bitmap
450 : * without worrying about ordering
451 : */
452 395790 : tbm_add_tuples(tbm, &it->t_tid, 1, recheck);
453 395790 : (*ntids)++;
454 : }
455 849924 : else if (scan->numberOfOrderBys == 0 && GistPageIsLeaf(page))
456 : {
457 : /*
458 : * Non-ordered scan, so report tuples in so->pageData[]
459 : */
460 747188 : so->pageData[so->nPageData].heapPtr = it->t_tid;
461 747188 : so->pageData[so->nPageData].recheck = recheck;
462 747188 : so->pageData[so->nPageData].offnum = i;
463 :
464 : /*
465 : * In an index-only scan, also fetch the data from the tuple. The
466 : * reconstructed tuples are stored in pageDataCxt.
467 : */
468 747188 : if (scan->xs_want_itup)
469 : {
470 517478 : oldcxt = MemoryContextSwitchTo(so->pageDataCxt);
471 1034956 : so->pageData[so->nPageData].recontup =
472 517478 : gistFetchTuple(giststate, r, it);
473 517478 : MemoryContextSwitchTo(oldcxt);
474 : }
475 747188 : so->nPageData++;
476 : }
477 : else
478 : {
479 : /*
480 : * Must push item into search queue. We get here for any lower
481 : * index page, and also for heap tuples if doing an ordered
482 : * search.
483 : */
484 : GISTSearchItem *item;
485 102736 : int nOrderBys = scan->numberOfOrderBys;
486 :
487 102736 : oldcxt = MemoryContextSwitchTo(so->queueCxt);
488 :
489 : /* Create new GISTSearchItem for this item */
490 102736 : item = palloc(SizeOfGISTSearchItem(scan->numberOfOrderBys));
491 :
492 102736 : if (GistPageIsLeaf(page))
493 : {
494 : /* Creating heap-tuple GISTSearchItem */
495 27180 : item->blkno = InvalidBlockNumber;
496 27180 : item->data.heap.heapPtr = it->t_tid;
497 27180 : item->data.heap.recheck = recheck;
498 27180 : item->data.heap.recheckDistances = recheck_distances;
499 :
500 : /*
501 : * In an index-only scan, also fetch the data from the tuple.
502 : */
503 27180 : if (scan->xs_want_itup)
504 13142 : item->data.heap.recontup = gistFetchTuple(giststate, r, it);
505 : }
506 : else
507 : {
508 : /* Creating index-page GISTSearchItem */
509 75556 : item->blkno = ItemPointerGetBlockNumber(&it->t_tid);
510 :
511 : /*
512 : * LSN of current page is lsn of parent page for child. We
513 : * only have a shared lock, so we need to get the LSN
514 : * atomically.
515 : */
516 75556 : item->data.parentlsn = BufferGetLSNAtomic(buffer);
517 : }
518 :
519 : /* Insert it into the queue using new distance data */
520 102736 : memcpy(item->distances, so->distances,
521 : sizeof(item->distances[0]) * nOrderBys);
522 :
523 102736 : pairingheap_add(so->queue, &item->phNode);
524 :
525 102736 : MemoryContextSwitchTo(oldcxt);
526 : }
527 : }
528 :
529 78672 : UnlockReleaseBuffer(buffer);
530 : }
531 :
532 : /*
533 : * Extract next item (in order) from search queue
534 : *
535 : * Returns a GISTSearchItem or NULL. Caller must pfree item when done with it.
536 : */
537 : static GISTSearchItem *
538 79564 : getNextGISTSearchItem(GISTScanOpaque so)
539 : {
540 : GISTSearchItem *item;
541 :
542 79564 : if (!pairingheap_is_empty(so->queue))
543 : {
544 73648 : item = (GISTSearchItem *) pairingheap_remove_first(so->queue);
545 : }
546 : else
547 : {
548 : /* Done when both heaps are empty */
549 5916 : item = NULL;
550 : }
551 :
552 : /* Return item; caller is responsible to pfree it */
553 79564 : return item;
554 : }
555 :
556 : /*
557 : * Fetch next heap tuple in an ordered search
558 : */
559 : static bool
560 1288 : getNextNearest(IndexScanDesc scan)
561 : {
562 1288 : GISTScanOpaque so = (GISTScanOpaque) scan->opaque;
563 1288 : bool res = false;
564 :
565 1288 : if (scan->xs_hitup)
566 : {
567 : /* free previously returned tuple */
568 850 : pfree(scan->xs_hitup);
569 850 : scan->xs_hitup = NULL;
570 : }
571 :
572 : do
573 : {
574 1622 : GISTSearchItem *item = getNextGISTSearchItem(so);
575 :
576 1622 : if (!item)
577 42 : break;
578 :
579 1580 : if (GISTSearchItemIsHeap(*item))
580 : {
581 : /* found a heap item at currently minimal distance */
582 1246 : scan->xs_heaptid = item->data.heap.heapPtr;
583 1246 : scan->xs_recheck = item->data.heap.recheck;
584 :
585 1246 : index_store_float8_orderby_distances(scan, so->orderByTypes,
586 1246 : item->distances,
587 1246 : item->data.heap.recheckDistances);
588 :
589 : /* in an index-only scan, also return the reconstructed tuple. */
590 1246 : if (scan->xs_want_itup)
591 918 : scan->xs_hitup = item->data.heap.recontup;
592 1246 : res = true;
593 : }
594 : else
595 : {
596 : /* visit an index page, extract its items into queue */
597 334 : CHECK_FOR_INTERRUPTS();
598 :
599 334 : gistScanPage(scan, item, item->distances, NULL, NULL);
600 : }
601 :
602 1580 : pfree(item);
603 1580 : } while (!res);
604 :
605 1288 : return res;
606 : }
607 :
608 : /*
609 : * gistgettuple() -- Get the next tuple in the scan
610 : */
611 : bool
612 752430 : gistgettuple(IndexScanDesc scan, ScanDirection dir)
613 : {
614 752430 : GISTScanOpaque so = (GISTScanOpaque) scan->opaque;
615 :
616 752430 : if (dir != ForwardScanDirection)
617 0 : elog(ERROR, "GiST only supports forward scan direction");
618 :
619 752430 : if (!so->qual_ok)
620 0 : return false;
621 :
622 752430 : if (so->firstCall)
623 : {
624 : /* Begin the scan by processing the root page */
625 : GISTSearchItem fakeItem;
626 :
627 4488 : pgstat_count_index_scan(scan->indexRelation);
628 :
629 4488 : so->firstCall = false;
630 4488 : so->curPageData = so->nPageData = 0;
631 4488 : scan->xs_hitup = NULL;
632 4488 : if (so->pageDataCxt)
633 680 : MemoryContextReset(so->pageDataCxt);
634 :
635 4488 : fakeItem.blkno = GIST_ROOT_BLKNO;
636 : memset(&fakeItem.data.parentlsn, 0, sizeof(GistNSN));
637 4488 : gistScanPage(scan, &fakeItem, NULL, NULL, NULL);
638 : }
639 :
640 752430 : if (scan->numberOfOrderBys > 0)
641 : {
642 : /* Must fetch tuples in strict distance order */
643 1288 : return getNextNearest(scan);
644 : }
645 : else
646 : {
647 : /* Fetch tuples index-page-at-a-time */
648 : for (;;)
649 : {
650 759708 : if (so->curPageData < so->nPageData)
651 : {
652 747050 : if (scan->kill_prior_tuple && so->curPageData > 0)
653 : {
654 :
655 482 : if (so->killedItems == NULL)
656 : {
657 : MemoryContext oldCxt =
658 438 : MemoryContextSwitchTo(so->giststate->scanCxt);
659 :
660 438 : so->killedItems =
661 438 : (OffsetNumber *) palloc(MaxIndexTuplesPerPage
662 : * sizeof(OffsetNumber));
663 :
664 438 : MemoryContextSwitchTo(oldCxt);
665 : }
666 482 : if (so->numKilled < MaxIndexTuplesPerPage)
667 482 : so->killedItems[so->numKilled++] =
668 482 : so->pageData[so->curPageData - 1].offnum;
669 : }
670 : /* continuing to return tuples from a leaf page */
671 747050 : scan->xs_heaptid = so->pageData[so->curPageData].heapPtr;
672 747050 : scan->xs_recheck = so->pageData[so->curPageData].recheck;
673 :
674 : /* in an index-only scan, also return the reconstructed tuple */
675 747050 : if (scan->xs_want_itup)
676 517478 : scan->xs_hitup = so->pageData[so->curPageData].recontup;
677 :
678 747050 : so->curPageData++;
679 :
680 747050 : return true;
681 : }
682 :
683 : /*
684 : * Check the last returned tuple and add it to killedItems if
685 : * necessary
686 : */
687 12658 : if (scan->kill_prior_tuple
688 4 : && so->curPageData > 0
689 4 : && so->curPageData == so->nPageData)
690 : {
691 :
692 4 : if (so->killedItems == NULL)
693 : {
694 : MemoryContext oldCxt =
695 4 : MemoryContextSwitchTo(so->giststate->scanCxt);
696 :
697 4 : so->killedItems =
698 4 : (OffsetNumber *) palloc(MaxIndexTuplesPerPage
699 : * sizeof(OffsetNumber));
700 :
701 4 : MemoryContextSwitchTo(oldCxt);
702 : }
703 4 : if (so->numKilled < MaxIndexTuplesPerPage)
704 4 : so->killedItems[so->numKilled++] =
705 4 : so->pageData[so->curPageData - 1].offnum;
706 : }
707 : /* find and process the next index page */
708 : do
709 : {
710 : GISTSearchItem *item;
711 :
712 15992 : if ((so->curBlkno != InvalidBlockNumber) && (so->numKilled > 0))
713 0 : gistkillitems(scan);
714 :
715 15992 : item = getNextGISTSearchItem(so);
716 :
717 15992 : if (!item)
718 4092 : return false;
719 :
720 11900 : CHECK_FOR_INTERRUPTS();
721 :
722 : /* save current item BlockNumber for next gistkillitems() call */
723 11900 : so->curBlkno = item->blkno;
724 :
725 : /*
726 : * While scanning a leaf page, ItemPointers of matching heap
727 : * tuples are stored in so->pageData. If there are any on
728 : * this page, we fall out of the inner "do" and loop around to
729 : * return them.
730 : */
731 11900 : gistScanPage(scan, item, item->distances, NULL, NULL);
732 :
733 11900 : pfree(item);
734 11900 : } while (so->nPageData == 0);
735 : }
736 : }
737 : }
738 :
739 : /*
740 : * gistgetbitmap() -- Get a bitmap of all heap tuple locations
741 : */
742 : int64
743 1782 : gistgetbitmap(IndexScanDesc scan, TIDBitmap *tbm)
744 : {
745 1782 : GISTScanOpaque so = (GISTScanOpaque) scan->opaque;
746 1782 : int64 ntids = 0;
747 : GISTSearchItem fakeItem;
748 :
749 1782 : if (!so->qual_ok)
750 0 : return 0;
751 :
752 1782 : pgstat_count_index_scan(scan->indexRelation);
753 :
754 : /* Begin the scan by processing the root page */
755 1782 : so->curPageData = so->nPageData = 0;
756 1782 : scan->xs_hitup = NULL;
757 1782 : if (so->pageDataCxt)
758 0 : MemoryContextReset(so->pageDataCxt);
759 :
760 1782 : fakeItem.blkno = GIST_ROOT_BLKNO;
761 : memset(&fakeItem.data.parentlsn, 0, sizeof(GistNSN));
762 1782 : gistScanPage(scan, &fakeItem, NULL, tbm, &ntids);
763 :
764 : /*
765 : * While scanning a leaf page, ItemPointers of matching heap tuples will
766 : * be stored directly into tbm, so we don't need to deal with them here.
767 : */
768 : for (;;)
769 60168 : {
770 61950 : GISTSearchItem *item = getNextGISTSearchItem(so);
771 :
772 61950 : if (!item)
773 1782 : break;
774 :
775 60168 : CHECK_FOR_INTERRUPTS();
776 :
777 60168 : gistScanPage(scan, item, item->distances, tbm, &ntids);
778 :
779 60168 : pfree(item);
780 : }
781 :
782 1782 : return ntids;
783 : }
784 :
785 : /*
786 : * Can we do index-only scans on the given index column?
787 : *
788 : * Opclasses that implement a fetch function support index-only scans.
789 : * Opclasses without compression functions also support index-only scans.
790 : * Included attributes always can be fetched for index-only scans.
791 : */
792 : bool
793 8602 : gistcanreturn(Relation index, int attno)
794 : {
795 17078 : if (attno > IndexRelationGetNumberOfKeyAttributes(index) ||
796 15870 : OidIsValid(index_getprocid(index, attno, GIST_FETCH_PROC)) ||
797 7394 : !OidIsValid(index_getprocid(index, attno, GIST_COMPRESS_PROC)))
798 5744 : return true;
799 : else
800 2858 : return false;
801 : }
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