Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * gist.c
4 : * interface routines for the postgres GiST index access method.
5 : *
6 : *
7 : * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
8 : * Portions Copyright (c) 1994, Regents of the University of California
9 : *
10 : * IDENTIFICATION
11 : * src/backend/access/gist/gist.c
12 : *
13 : *-------------------------------------------------------------------------
14 : */
15 : #include "postgres.h"
16 :
17 : #include "access/gist_private.h"
18 : #include "access/gistscan.h"
19 : #include "access/xloginsert.h"
20 : #include "catalog/pg_collation.h"
21 : #include "commands/vacuum.h"
22 : #include "miscadmin.h"
23 : #include "nodes/execnodes.h"
24 : #include "storage/predicate.h"
25 : #include "utils/fmgrprotos.h"
26 : #include "utils/index_selfuncs.h"
27 : #include "utils/memutils.h"
28 : #include "utils/rel.h"
29 :
30 : /* non-export function prototypes */
31 : static void gistfixsplit(GISTInsertState *state, GISTSTATE *giststate);
32 : static bool gistinserttuple(GISTInsertState *state, GISTInsertStack *stack,
33 : GISTSTATE *giststate, IndexTuple tuple, OffsetNumber oldoffnum);
34 : static bool gistinserttuples(GISTInsertState *state, GISTInsertStack *stack,
35 : GISTSTATE *giststate,
36 : IndexTuple *tuples, int ntup, OffsetNumber oldoffnum,
37 : Buffer leftchild, Buffer rightchild,
38 : bool unlockbuf, bool unlockleftchild);
39 : static void gistfinishsplit(GISTInsertState *state, GISTInsertStack *stack,
40 : GISTSTATE *giststate, List *splitinfo, bool unlockbuf);
41 : static void gistprunepage(Relation rel, Page page, Buffer buffer,
42 : Relation heapRel);
43 :
44 :
45 : #define ROTATEDIST(d) do { \
46 : SplitPageLayout *tmp = (SplitPageLayout *) palloc0(sizeof(SplitPageLayout)); \
47 : tmp->block.blkno = InvalidBlockNumber; \
48 : tmp->buffer = InvalidBuffer; \
49 : tmp->next = (d); \
50 : (d)=tmp; \
51 : } while(0)
52 :
53 :
54 : /*
55 : * GiST handler function: return IndexAmRoutine with access method parameters
56 : * and callbacks.
57 : */
58 : Datum
59 11970 : gisthandler(PG_FUNCTION_ARGS)
60 : {
61 11970 : IndexAmRoutine *amroutine = makeNode(IndexAmRoutine);
62 :
63 11970 : amroutine->amstrategies = 0;
64 11970 : amroutine->amsupport = GISTNProcs;
65 11970 : amroutine->amoptsprocnum = GIST_OPTIONS_PROC;
66 11970 : amroutine->amcanorder = false;
67 11970 : amroutine->amcanorderbyop = true;
68 11970 : amroutine->amcanhash = false;
69 11970 : amroutine->amconsistentequality = false;
70 11970 : amroutine->amconsistentordering = false;
71 11970 : amroutine->amcanbackward = false;
72 11970 : amroutine->amcanunique = false;
73 11970 : amroutine->amcanmulticol = true;
74 11970 : amroutine->amoptionalkey = true;
75 11970 : amroutine->amsearcharray = false;
76 11970 : amroutine->amsearchnulls = true;
77 11970 : amroutine->amstorage = true;
78 11970 : amroutine->amclusterable = true;
79 11970 : amroutine->ampredlocks = true;
80 11970 : amroutine->amcanparallel = false;
81 11970 : amroutine->amcanbuildparallel = false;
82 11970 : amroutine->amcaninclude = true;
83 11970 : amroutine->amusemaintenanceworkmem = false;
84 11970 : amroutine->amsummarizing = false;
85 11970 : amroutine->amparallelvacuumoptions =
86 : VACUUM_OPTION_PARALLEL_BULKDEL | VACUUM_OPTION_PARALLEL_COND_CLEANUP;
87 11970 : amroutine->amkeytype = InvalidOid;
88 :
89 11970 : amroutine->ambuild = gistbuild;
90 11970 : amroutine->ambuildempty = gistbuildempty;
91 11970 : amroutine->aminsert = gistinsert;
92 11970 : amroutine->aminsertcleanup = NULL;
93 11970 : amroutine->ambulkdelete = gistbulkdelete;
94 11970 : amroutine->amvacuumcleanup = gistvacuumcleanup;
95 11970 : amroutine->amcanreturn = gistcanreturn;
96 11970 : amroutine->amcostestimate = gistcostestimate;
97 11970 : amroutine->amgettreeheight = NULL;
98 11970 : amroutine->amoptions = gistoptions;
99 11970 : amroutine->amproperty = gistproperty;
100 11970 : amroutine->ambuildphasename = NULL;
101 11970 : amroutine->amvalidate = gistvalidate;
102 11970 : amroutine->amadjustmembers = gistadjustmembers;
103 11970 : amroutine->ambeginscan = gistbeginscan;
104 11970 : amroutine->amrescan = gistrescan;
105 11970 : amroutine->amgettuple = gistgettuple;
106 11970 : amroutine->amgetbitmap = gistgetbitmap;
107 11970 : amroutine->amendscan = gistendscan;
108 11970 : amroutine->ammarkpos = NULL;
109 11970 : amroutine->amrestrpos = NULL;
110 11970 : amroutine->amestimateparallelscan = NULL;
111 11970 : amroutine->aminitparallelscan = NULL;
112 11970 : amroutine->amparallelrescan = NULL;
113 11970 : amroutine->amtranslatestrategy = NULL;
114 11970 : amroutine->amtranslatecmptype = gisttranslatecmptype;
115 :
116 11970 : PG_RETURN_POINTER(amroutine);
117 : }
118 :
119 : /*
120 : * Create and return a temporary memory context for use by GiST. We
121 : * _always_ invoke user-provided methods in a temporary memory
122 : * context, so that memory leaks in those functions cannot cause
123 : * problems. Also, we use some additional temporary contexts in the
124 : * GiST code itself, to avoid the need to do some awkward manual
125 : * memory management.
126 : */
127 : MemoryContext
128 9564 : createTempGistContext(void)
129 : {
130 9564 : return AllocSetContextCreate(CurrentMemoryContext,
131 : "GiST temporary context",
132 : ALLOCSET_DEFAULT_SIZES);
133 : }
134 :
135 : /*
136 : * gistbuildempty() -- build an empty gist index in the initialization fork
137 : */
138 : void
139 10 : gistbuildempty(Relation index)
140 : {
141 : Buffer buffer;
142 :
143 : /* Initialize the root page */
144 10 : buffer = ExtendBufferedRel(BMR_REL(index), INIT_FORKNUM, NULL,
145 : EB_SKIP_EXTENSION_LOCK | EB_LOCK_FIRST);
146 :
147 : /* Initialize and xlog buffer */
148 10 : START_CRIT_SECTION();
149 10 : GISTInitBuffer(buffer, F_LEAF);
150 10 : MarkBufferDirty(buffer);
151 10 : log_newpage_buffer(buffer, true);
152 10 : END_CRIT_SECTION();
153 :
154 : /* Unlock and release the buffer */
155 10 : UnlockReleaseBuffer(buffer);
156 10 : }
157 :
158 : /*
159 : * gistinsert -- wrapper for GiST tuple insertion.
160 : *
161 : * This is the public interface routine for tuple insertion in GiSTs.
162 : * It doesn't do any work; just locks the relation and passes the buck.
163 : */
164 : bool
165 304330 : gistinsert(Relation r, Datum *values, bool *isnull,
166 : ItemPointer ht_ctid, Relation heapRel,
167 : IndexUniqueCheck checkUnique,
168 : bool indexUnchanged,
169 : IndexInfo *indexInfo)
170 : {
171 304330 : GISTSTATE *giststate = (GISTSTATE *) indexInfo->ii_AmCache;
172 : IndexTuple itup;
173 : MemoryContext oldCxt;
174 :
175 : /* Initialize GISTSTATE cache if first call in this statement */
176 304330 : if (giststate == NULL)
177 : {
178 1860 : oldCxt = MemoryContextSwitchTo(indexInfo->ii_Context);
179 1860 : giststate = initGISTstate(r);
180 1860 : giststate->tempCxt = createTempGistContext();
181 1860 : indexInfo->ii_AmCache = giststate;
182 1860 : MemoryContextSwitchTo(oldCxt);
183 : }
184 :
185 304330 : oldCxt = MemoryContextSwitchTo(giststate->tempCxt);
186 :
187 304330 : itup = gistFormTuple(giststate, r, values, isnull, true);
188 304328 : itup->t_tid = *ht_ctid;
189 :
190 304328 : gistdoinsert(r, itup, 0, giststate, heapRel, false);
191 :
192 : /* cleanup */
193 304316 : MemoryContextSwitchTo(oldCxt);
194 304316 : MemoryContextReset(giststate->tempCxt);
195 :
196 304316 : return false;
197 : }
198 :
199 :
200 : /*
201 : * Place tuples from 'itup' to 'buffer'. If 'oldoffnum' is valid, the tuple
202 : * at that offset is atomically removed along with inserting the new tuples.
203 : * This is used to replace a tuple with a new one.
204 : *
205 : * If 'leftchildbuf' is valid, we're inserting the downlink for the page
206 : * to the right of 'leftchildbuf', or updating the downlink for 'leftchildbuf'.
207 : * F_FOLLOW_RIGHT flag on 'leftchildbuf' is cleared and NSN is set.
208 : *
209 : * If 'markfollowright' is true and the page is split, the left child is
210 : * marked with F_FOLLOW_RIGHT flag. That is the normal case. During buffered
211 : * index build, however, there is no concurrent access and the page splitting
212 : * is done in a slightly simpler fashion, and false is passed.
213 : *
214 : * If there is not enough room on the page, it is split. All the split
215 : * pages are kept pinned and locked and returned in *splitinfo, the caller
216 : * is responsible for inserting the downlinks for them. However, if
217 : * 'buffer' is the root page and it needs to be split, gistplacetopage()
218 : * performs the split as one atomic operation, and *splitinfo is set to NIL.
219 : * In that case, we continue to hold the root page locked, and the child
220 : * pages are released; note that new tuple(s) are *not* on the root page
221 : * but in one of the new child pages.
222 : *
223 : * If 'newblkno' is not NULL, returns the block number of page the first
224 : * new/updated tuple was inserted to. Usually it's the given page, but could
225 : * be its right sibling if the page was split.
226 : *
227 : * Returns 'true' if the page was split, 'false' otherwise.
228 : */
229 : bool
230 1749084 : gistplacetopage(Relation rel, Size freespace, GISTSTATE *giststate,
231 : Buffer buffer,
232 : IndexTuple *itup, int ntup, OffsetNumber oldoffnum,
233 : BlockNumber *newblkno,
234 : Buffer leftchildbuf,
235 : List **splitinfo,
236 : bool markfollowright,
237 : Relation heapRel,
238 : bool is_build)
239 : {
240 1749084 : BlockNumber blkno = BufferGetBlockNumber(buffer);
241 1749084 : Page page = BufferGetPage(buffer);
242 1749084 : bool is_leaf = (GistPageIsLeaf(page)) ? true : false;
243 : XLogRecPtr recptr;
244 : bool is_split;
245 :
246 : /*
247 : * Refuse to modify a page that's incompletely split. This should not
248 : * happen because we finish any incomplete splits while we walk down the
249 : * tree. However, it's remotely possible that another concurrent inserter
250 : * splits a parent page, and errors out before completing the split. We
251 : * will just throw an error in that case, and leave any split we had in
252 : * progress unfinished too. The next insert that comes along will clean up
253 : * the mess.
254 : */
255 1749084 : if (GistFollowRight(page))
256 0 : elog(ERROR, "concurrent GiST page split was incomplete");
257 :
258 : /* should never try to insert to a deleted page */
259 : Assert(!GistPageIsDeleted(page));
260 :
261 1749084 : *splitinfo = NIL;
262 :
263 : /*
264 : * if isupdate, remove old key: This node's key has been modified, either
265 : * because a child split occurred or because we needed to adjust our key
266 : * for an insert in a child node. Therefore, remove the old version of
267 : * this node's key.
268 : *
269 : * for WAL replay, in the non-split case we handle this by setting up a
270 : * one-element todelete array; in the split case, it's handled implicitly
271 : * because the tuple vector passed to gistSplit won't include this tuple.
272 : */
273 1749084 : is_split = gistnospace(page, itup, ntup, oldoffnum, freespace);
274 :
275 : /*
276 : * If leaf page is full, try at first to delete dead tuples. And then
277 : * check again.
278 : */
279 1749084 : if (is_split && GistPageIsLeaf(page) && GistPageHasGarbage(page))
280 : {
281 0 : gistprunepage(rel, page, buffer, heapRel);
282 0 : is_split = gistnospace(page, itup, ntup, oldoffnum, freespace);
283 : }
284 :
285 1749084 : if (is_split)
286 : {
287 : /* no space for insertion */
288 : IndexTuple *itvec;
289 : int tlen;
290 25272 : SplitPageLayout *dist = NULL,
291 : *ptr;
292 25272 : BlockNumber oldrlink = InvalidBlockNumber;
293 25272 : GistNSN oldnsn = 0;
294 : SplitPageLayout rootpg;
295 : bool is_rootsplit;
296 : int npage;
297 :
298 25272 : is_rootsplit = (blkno == GIST_ROOT_BLKNO);
299 :
300 : /*
301 : * Form index tuples vector to split. If we're replacing an old tuple,
302 : * remove the old version from the vector.
303 : */
304 25272 : itvec = gistextractpage(page, &tlen);
305 25272 : if (OffsetNumberIsValid(oldoffnum))
306 : {
307 : /* on inner page we should remove old tuple */
308 5078 : int pos = oldoffnum - FirstOffsetNumber;
309 :
310 5078 : tlen--;
311 5078 : if (pos != tlen)
312 3258 : memmove(itvec + pos, itvec + pos + 1, sizeof(IndexTuple) * (tlen - pos));
313 : }
314 25272 : itvec = gistjoinvector(itvec, &tlen, itup, ntup);
315 25272 : dist = gistSplit(rel, page, itvec, tlen, giststate);
316 :
317 : /*
318 : * Check that split didn't produce too many pages.
319 : */
320 25272 : npage = 0;
321 75878 : for (ptr = dist; ptr; ptr = ptr->next)
322 50606 : npage++;
323 : /* in a root split, we'll add one more page to the list below */
324 25272 : if (is_rootsplit)
325 408 : npage++;
326 25272 : if (npage > GIST_MAX_SPLIT_PAGES)
327 0 : elog(ERROR, "GiST page split into too many halves (%d, maximum %d)",
328 : npage, GIST_MAX_SPLIT_PAGES);
329 :
330 : /*
331 : * Set up pages to work with. Allocate new buffers for all but the
332 : * leftmost page. The original page becomes the new leftmost page, and
333 : * is just replaced with the new contents.
334 : *
335 : * For a root-split, allocate new buffers for all child pages, the
336 : * original page is overwritten with new root page containing
337 : * downlinks to the new child pages.
338 : */
339 25272 : ptr = dist;
340 25272 : if (!is_rootsplit)
341 : {
342 : /* save old rightlink and NSN */
343 24864 : oldrlink = GistPageGetOpaque(page)->rightlink;
344 24864 : oldnsn = GistPageGetNSN(page);
345 :
346 24864 : dist->buffer = buffer;
347 24864 : dist->block.blkno = BufferGetBlockNumber(buffer);
348 24864 : dist->page = PageGetTempPageCopySpecial(BufferGetPage(buffer));
349 :
350 : /* clean all flags except F_LEAF */
351 24864 : GistPageGetOpaque(dist->page)->flags = (is_leaf) ? F_LEAF : 0;
352 :
353 24864 : ptr = ptr->next;
354 : }
355 51014 : for (; ptr; ptr = ptr->next)
356 : {
357 : /* Allocate new page */
358 25742 : ptr->buffer = gistNewBuffer(rel, heapRel);
359 25742 : GISTInitBuffer(ptr->buffer, (is_leaf) ? F_LEAF : 0);
360 25742 : ptr->page = BufferGetPage(ptr->buffer);
361 25742 : ptr->block.blkno = BufferGetBlockNumber(ptr->buffer);
362 25742 : PredicateLockPageSplit(rel,
363 : BufferGetBlockNumber(buffer),
364 : BufferGetBlockNumber(ptr->buffer));
365 : }
366 :
367 : /*
368 : * Now that we know which blocks the new pages go to, set up downlink
369 : * tuples to point to them.
370 : */
371 75878 : for (ptr = dist; ptr; ptr = ptr->next)
372 : {
373 50606 : ItemPointerSetBlockNumber(&(ptr->itup->t_tid), ptr->block.blkno);
374 50606 : GistTupleSetValid(ptr->itup);
375 : }
376 :
377 : /*
378 : * If this is a root split, we construct the new root page with the
379 : * downlinks here directly, instead of requiring the caller to insert
380 : * them. Add the new root page to the list along with the child pages.
381 : */
382 25272 : if (is_rootsplit)
383 : {
384 : IndexTuple *downlinks;
385 408 : int ndownlinks = 0;
386 : int i;
387 :
388 408 : rootpg.buffer = buffer;
389 408 : rootpg.page = PageGetTempPageCopySpecial(BufferGetPage(rootpg.buffer));
390 408 : GistPageGetOpaque(rootpg.page)->flags = 0;
391 :
392 : /* Prepare a vector of all the downlinks */
393 1230 : for (ptr = dist; ptr; ptr = ptr->next)
394 822 : ndownlinks++;
395 408 : downlinks = palloc(sizeof(IndexTuple) * ndownlinks);
396 1230 : for (i = 0, ptr = dist; ptr; ptr = ptr->next)
397 822 : downlinks[i++] = ptr->itup;
398 :
399 408 : rootpg.block.blkno = GIST_ROOT_BLKNO;
400 408 : rootpg.block.num = ndownlinks;
401 408 : rootpg.list = gistfillitupvec(downlinks, ndownlinks,
402 : &(rootpg.lenlist));
403 408 : rootpg.itup = NULL;
404 :
405 408 : rootpg.next = dist;
406 408 : dist = &rootpg;
407 : }
408 : else
409 : {
410 : /* Prepare split-info to be returned to caller */
411 74648 : for (ptr = dist; ptr; ptr = ptr->next)
412 : {
413 49784 : GISTPageSplitInfo *si = palloc(sizeof(GISTPageSplitInfo));
414 :
415 49784 : si->buf = ptr->buffer;
416 49784 : si->downlink = ptr->itup;
417 49784 : *splitinfo = lappend(*splitinfo, si);
418 : }
419 : }
420 :
421 : /*
422 : * Fill all pages. All the pages are new, ie. freshly allocated empty
423 : * pages, or a temporary copy of the old page.
424 : */
425 76286 : for (ptr = dist; ptr; ptr = ptr->next)
426 : {
427 51014 : char *data = (char *) (ptr->list);
428 :
429 1905562 : for (int i = 0; i < ptr->block.num; i++)
430 : {
431 1854548 : IndexTuple thistup = (IndexTuple) data;
432 :
433 1854548 : if (PageAddItem(ptr->page, (Item) data, IndexTupleSize(thistup), i + FirstOffsetNumber, false, false) == InvalidOffsetNumber)
434 0 : elog(ERROR, "failed to add item to index page in \"%s\"", RelationGetRelationName(rel));
435 :
436 : /*
437 : * If this is the first inserted/updated tuple, let the caller
438 : * know which page it landed on.
439 : */
440 1854548 : if (newblkno && ItemPointerEquals(&thistup->t_tid, &(*itup)->t_tid))
441 774 : *newblkno = ptr->block.blkno;
442 :
443 1854548 : data += IndexTupleSize(thistup);
444 : }
445 :
446 : /* Set up rightlinks */
447 51014 : if (ptr->next && ptr->block.blkno != GIST_ROOT_BLKNO)
448 50668 : GistPageGetOpaque(ptr->page)->rightlink =
449 25334 : ptr->next->block.blkno;
450 : else
451 25680 : GistPageGetOpaque(ptr->page)->rightlink = oldrlink;
452 :
453 : /*
454 : * Mark the all but the right-most page with the follow-right
455 : * flag. It will be cleared as soon as the downlink is inserted
456 : * into the parent, but this ensures that if we error out before
457 : * that, the index is still consistent. (in buffering build mode,
458 : * any error will abort the index build anyway, so this is not
459 : * needed.)
460 : */
461 51014 : if (ptr->next && !is_rootsplit && markfollowright)
462 24152 : GistMarkFollowRight(ptr->page);
463 : else
464 26862 : GistClearFollowRight(ptr->page);
465 :
466 : /*
467 : * Copy the NSN of the original page to all pages. The
468 : * F_FOLLOW_RIGHT flags ensure that scans will follow the
469 : * rightlinks until the downlinks are inserted.
470 : */
471 51014 : GistPageSetNSN(ptr->page, oldnsn);
472 : }
473 :
474 : /*
475 : * gistXLogSplit() needs to WAL log a lot of pages, prepare WAL
476 : * insertion for that. NB: The number of pages and data segments
477 : * specified here must match the calculations in gistXLogSplit()!
478 : */
479 25272 : if (!is_build && RelationNeedsWAL(rel))
480 3472 : XLogEnsureRecordSpace(npage, 1 + npage * 2);
481 :
482 25272 : START_CRIT_SECTION();
483 :
484 : /*
485 : * Must mark buffers dirty before XLogInsert, even though we'll still
486 : * be changing their opaque fields below.
487 : */
488 76286 : for (ptr = dist; ptr; ptr = ptr->next)
489 51014 : MarkBufferDirty(ptr->buffer);
490 25272 : if (BufferIsValid(leftchildbuf))
491 4954 : MarkBufferDirty(leftchildbuf);
492 :
493 : /*
494 : * The first page in the chain was a temporary working copy meant to
495 : * replace the old page. Copy it over the old page.
496 : */
497 25272 : PageRestoreTempPage(dist->page, BufferGetPage(dist->buffer));
498 25272 : dist->page = BufferGetPage(dist->buffer);
499 :
500 : /*
501 : * Write the WAL record.
502 : *
503 : * If we're building a new index, however, we don't WAL-log changes
504 : * yet. The LSN-NSN interlock between parent and child requires that
505 : * LSNs never move backwards, so set the LSNs to a value that's
506 : * smaller than any real or fake unlogged LSN that might be generated
507 : * later. (There can't be any concurrent scans during index build, so
508 : * we don't need to be able to detect concurrent splits yet.)
509 : */
510 25272 : if (is_build)
511 21794 : recptr = GistBuildLSN;
512 : else
513 : {
514 3478 : if (RelationNeedsWAL(rel))
515 3472 : recptr = gistXLogSplit(is_leaf,
516 : dist, oldrlink, oldnsn, leftchildbuf,
517 : markfollowright);
518 : else
519 6 : recptr = gistGetFakeLSN(rel);
520 : }
521 :
522 76286 : for (ptr = dist; ptr; ptr = ptr->next)
523 51014 : PageSetLSN(ptr->page, recptr);
524 :
525 : /*
526 : * Return the new child buffers to the caller.
527 : *
528 : * If this was a root split, we've already inserted the downlink
529 : * pointers, in the form of a new root page. Therefore we can release
530 : * all the new buffers, and keep just the root page locked.
531 : */
532 25272 : if (is_rootsplit)
533 : {
534 1230 : for (ptr = dist->next; ptr; ptr = ptr->next)
535 822 : UnlockReleaseBuffer(ptr->buffer);
536 : }
537 : }
538 : else
539 : {
540 : /*
541 : * Enough space. We always get here if ntup==0.
542 : */
543 1723812 : START_CRIT_SECTION();
544 :
545 : /*
546 : * Delete old tuple if any, then insert new tuple(s) if any. If
547 : * possible, use the fast path of PageIndexTupleOverwrite.
548 : */
549 1723812 : if (OffsetNumberIsValid(oldoffnum))
550 : {
551 759920 : if (ntup == 1)
552 : {
553 : /* One-for-one replacement, so use PageIndexTupleOverwrite */
554 740028 : if (!PageIndexTupleOverwrite(page, oldoffnum, (Item) *itup,
555 : IndexTupleSize(*itup)))
556 0 : elog(ERROR, "failed to add item to index page in \"%s\"",
557 : RelationGetRelationName(rel));
558 : }
559 : else
560 : {
561 : /* Delete old, then append new tuple(s) to page */
562 19892 : PageIndexTupleDelete(page, oldoffnum);
563 19892 : gistfillbuffer(page, itup, ntup, InvalidOffsetNumber);
564 : }
565 : }
566 : else
567 : {
568 : /* Just append new tuples at the end of the page */
569 963892 : gistfillbuffer(page, itup, ntup, InvalidOffsetNumber);
570 : }
571 :
572 1723812 : MarkBufferDirty(buffer);
573 :
574 1723812 : if (BufferIsValid(leftchildbuf))
575 19198 : MarkBufferDirty(leftchildbuf);
576 :
577 1723812 : if (is_build)
578 1229172 : recptr = GistBuildLSN;
579 : else
580 : {
581 494640 : if (RelationNeedsWAL(rel))
582 494562 : {
583 494562 : OffsetNumber ndeloffs = 0,
584 : deloffs[1];
585 :
586 494562 : if (OffsetNumberIsValid(oldoffnum))
587 : {
588 193778 : deloffs[0] = oldoffnum;
589 193778 : ndeloffs = 1;
590 : }
591 :
592 494562 : recptr = gistXLogUpdate(buffer,
593 : deloffs, ndeloffs, itup, ntup,
594 : leftchildbuf);
595 : }
596 : else
597 78 : recptr = gistGetFakeLSN(rel);
598 : }
599 1723812 : PageSetLSN(page, recptr);
600 :
601 1723812 : if (newblkno)
602 104370 : *newblkno = blkno;
603 : }
604 :
605 : /*
606 : * If we inserted the downlink for a child page, set NSN and clear
607 : * F_FOLLOW_RIGHT flag on the left child, so that concurrent scans know to
608 : * follow the rightlink if and only if they looked at the parent page
609 : * before we inserted the downlink.
610 : *
611 : * Note that we do this *after* writing the WAL record. That means that
612 : * the possible full page image in the WAL record does not include these
613 : * changes, and they must be replayed even if the page is restored from
614 : * the full page image. There's a chicken-and-egg problem: if we updated
615 : * the child pages first, we wouldn't know the recptr of the WAL record
616 : * we're about to write.
617 : */
618 1749084 : if (BufferIsValid(leftchildbuf))
619 : {
620 24152 : Page leftpg = BufferGetPage(leftchildbuf);
621 :
622 24152 : GistPageSetNSN(leftpg, recptr);
623 24152 : GistClearFollowRight(leftpg);
624 :
625 24152 : PageSetLSN(leftpg, recptr);
626 : }
627 :
628 1749084 : END_CRIT_SECTION();
629 :
630 1749084 : return is_split;
631 : }
632 :
633 : /*
634 : * Workhorse routine for doing insertion into a GiST index. Note that
635 : * this routine assumes it is invoked in a short-lived memory context,
636 : * so it does not bother releasing palloc'd allocations.
637 : */
638 : void
639 948612 : gistdoinsert(Relation r, IndexTuple itup, Size freespace,
640 : GISTSTATE *giststate, Relation heapRel, bool is_build)
641 : {
642 : ItemId iid;
643 : IndexTuple idxtuple;
644 : GISTInsertStack firststack;
645 : GISTInsertStack *stack;
646 : GISTInsertState state;
647 948612 : bool xlocked = false;
648 :
649 948612 : memset(&state, 0, sizeof(GISTInsertState));
650 948612 : state.freespace = freespace;
651 948612 : state.r = r;
652 948612 : state.heapRel = heapRel;
653 948612 : state.is_build = is_build;
654 :
655 : /* Start from the root */
656 948612 : firststack.blkno = GIST_ROOT_BLKNO;
657 948612 : firststack.lsn = 0;
658 948612 : firststack.retry_from_parent = false;
659 948612 : firststack.parent = NULL;
660 948612 : firststack.downlinkoffnum = InvalidOffsetNumber;
661 948612 : state.stack = stack = &firststack;
662 :
663 : /*
664 : * Walk down along the path of smallest penalty, updating the parent
665 : * pointers with the key we're inserting as we go. If we crash in the
666 : * middle, the tree is consistent, although the possible parent updates
667 : * were a waste.
668 : */
669 : for (;;)
670 : {
671 : /*
672 : * If we split an internal page while descending the tree, we have to
673 : * retry at the parent. (Normally, the LSN-NSN interlock below would
674 : * also catch this and cause us to retry. But LSNs are not updated
675 : * during index build.)
676 : */
677 2133826 : while (stack->retry_from_parent)
678 : {
679 140 : if (xlocked)
680 0 : LockBuffer(stack->buffer, GIST_UNLOCK);
681 140 : xlocked = false;
682 140 : ReleaseBuffer(stack->buffer);
683 140 : state.stack = stack = stack->parent;
684 : }
685 :
686 2133686 : if (XLogRecPtrIsInvalid(stack->lsn))
687 2133580 : stack->buffer = ReadBuffer(state.r, stack->blkno);
688 :
689 : /*
690 : * Be optimistic and grab shared lock first. Swap it for an exclusive
691 : * lock later if we need to update the page.
692 : */
693 2133686 : if (!xlocked)
694 : {
695 2133684 : LockBuffer(stack->buffer, GIST_SHARE);
696 2133684 : gistcheckpage(state.r, stack->buffer);
697 : }
698 :
699 2133686 : stack->page = (Page) BufferGetPage(stack->buffer);
700 2133686 : stack->lsn = xlocked ?
701 2133686 : PageGetLSN(stack->page) : BufferGetLSNAtomic(stack->buffer);
702 : Assert(!RelationNeedsWAL(state.r) || !XLogRecPtrIsInvalid(stack->lsn));
703 :
704 : /*
705 : * If this page was split but the downlink was never inserted to the
706 : * parent because the inserting backend crashed before doing that, fix
707 : * that now.
708 : */
709 2133686 : if (GistFollowRight(stack->page))
710 : {
711 0 : if (!xlocked)
712 : {
713 0 : LockBuffer(stack->buffer, GIST_UNLOCK);
714 0 : LockBuffer(stack->buffer, GIST_EXCLUSIVE);
715 0 : xlocked = true;
716 : /* someone might've completed the split when we unlocked */
717 0 : if (!GistFollowRight(stack->page))
718 0 : continue;
719 : }
720 0 : gistfixsplit(&state, giststate);
721 :
722 0 : UnlockReleaseBuffer(stack->buffer);
723 0 : xlocked = false;
724 0 : state.stack = stack = stack->parent;
725 0 : continue;
726 : }
727 :
728 3318684 : if ((stack->blkno != GIST_ROOT_BLKNO &&
729 1184998 : stack->parent->lsn < GistPageGetNSN(stack->page)) ||
730 2133686 : GistPageIsDeleted(stack->page))
731 : {
732 : /*
733 : * Concurrent split or page deletion detected. There's no
734 : * guarantee that the downlink for this page is consistent with
735 : * the tuple we're inserting anymore, so go back to parent and
736 : * rechoose the best child.
737 : */
738 0 : UnlockReleaseBuffer(stack->buffer);
739 0 : xlocked = false;
740 0 : state.stack = stack = stack->parent;
741 0 : continue;
742 : }
743 :
744 2133686 : if (!GistPageIsLeaf(stack->page))
745 : {
746 : /*
747 : * This is an internal page so continue to walk down the tree.
748 : * Find the child node that has the minimum insertion penalty.
749 : */
750 : BlockNumber childblkno;
751 : IndexTuple newtup;
752 : GISTInsertStack *item;
753 : OffsetNumber downlinkoffnum;
754 :
755 1185074 : downlinkoffnum = gistchoose(state.r, stack->page, itup, giststate);
756 1185074 : iid = PageGetItemId(stack->page, downlinkoffnum);
757 1185074 : idxtuple = (IndexTuple) PageGetItem(stack->page, iid);
758 1185074 : childblkno = ItemPointerGetBlockNumber(&(idxtuple->t_tid));
759 :
760 : /*
761 : * Check that it's not a leftover invalid tuple from pre-9.1
762 : */
763 1185074 : if (GistTupleIsInvalid(idxtuple))
764 0 : ereport(ERROR,
765 : (errmsg("index \"%s\" contains an inner tuple marked as invalid",
766 : RelationGetRelationName(r)),
767 : errdetail("This is caused by an incomplete page split at crash recovery before upgrading to PostgreSQL 9.1."),
768 : errhint("Please REINDEX it.")));
769 :
770 : /*
771 : * Check that the key representing the target child node is
772 : * consistent with the key we're inserting. Update it if it's not.
773 : */
774 1185074 : newtup = gistgetadjusted(state.r, idxtuple, itup, giststate);
775 1185074 : if (newtup)
776 : {
777 : /*
778 : * Swap shared lock for an exclusive one. Beware, the page may
779 : * change while we unlock/lock the page...
780 : */
781 671188 : if (!xlocked)
782 : {
783 671188 : LockBuffer(stack->buffer, GIST_UNLOCK);
784 671188 : LockBuffer(stack->buffer, GIST_EXCLUSIVE);
785 671188 : xlocked = true;
786 671188 : stack->page = (Page) BufferGetPage(stack->buffer);
787 :
788 671188 : if (PageGetLSN(stack->page) != stack->lsn)
789 : {
790 : /* the page was changed while we unlocked it, retry */
791 0 : continue;
792 : }
793 : }
794 :
795 : /*
796 : * Update the tuple.
797 : *
798 : * We still hold the lock after gistinserttuple(), but it
799 : * might have to split the page to make the updated tuple fit.
800 : * In that case the updated tuple might migrate to the other
801 : * half of the split, so we have to go back to the parent and
802 : * descend back to the half that's a better fit for the new
803 : * tuple.
804 : */
805 671188 : if (gistinserttuple(&state, stack, giststate, newtup,
806 : downlinkoffnum))
807 : {
808 : /*
809 : * If this was a root split, the root page continues to be
810 : * the parent and the updated tuple went to one of the
811 : * child pages, so we just need to retry from the root
812 : * page.
813 : */
814 106 : if (stack->blkno != GIST_ROOT_BLKNO)
815 : {
816 104 : UnlockReleaseBuffer(stack->buffer);
817 104 : xlocked = false;
818 104 : state.stack = stack = stack->parent;
819 : }
820 106 : continue;
821 : }
822 : }
823 1184968 : LockBuffer(stack->buffer, GIST_UNLOCK);
824 1184968 : xlocked = false;
825 :
826 : /* descend to the chosen child */
827 1184968 : item = (GISTInsertStack *) palloc0(sizeof(GISTInsertStack));
828 1184968 : item->blkno = childblkno;
829 1184968 : item->parent = stack;
830 1184968 : item->downlinkoffnum = downlinkoffnum;
831 1184968 : state.stack = stack = item;
832 : }
833 : else
834 : {
835 : /*
836 : * Leaf page. Insert the new key. We've already updated all the
837 : * parents on the way down, but we might have to split the page if
838 : * it doesn't fit. gistinserttuple() will take care of that.
839 : */
840 :
841 : /*
842 : * Swap shared lock for an exclusive one. Be careful, the page may
843 : * change while we unlock/lock the page...
844 : */
845 948612 : if (!xlocked)
846 : {
847 948612 : LockBuffer(stack->buffer, GIST_UNLOCK);
848 948612 : LockBuffer(stack->buffer, GIST_EXCLUSIVE);
849 948612 : xlocked = true;
850 948612 : stack->page = (Page) BufferGetPage(stack->buffer);
851 948612 : stack->lsn = PageGetLSN(stack->page);
852 :
853 948612 : if (stack->blkno == GIST_ROOT_BLKNO)
854 : {
855 : /*
856 : * the only page that can become inner instead of leaf is
857 : * the root page, so for root we should recheck it
858 : */
859 55284 : if (!GistPageIsLeaf(stack->page))
860 : {
861 : /*
862 : * very rare situation: during unlock/lock index with
863 : * number of pages = 1 was increased
864 : */
865 0 : LockBuffer(stack->buffer, GIST_UNLOCK);
866 0 : xlocked = false;
867 0 : continue;
868 : }
869 :
870 : /*
871 : * we don't need to check root split, because checking
872 : * leaf/inner is enough to recognize split for root
873 : */
874 : }
875 1786656 : else if ((GistFollowRight(stack->page) ||
876 893328 : stack->parent->lsn < GistPageGetNSN(stack->page)) ||
877 893328 : GistPageIsDeleted(stack->page))
878 : {
879 : /*
880 : * The page was split or deleted while we momentarily
881 : * unlocked the page. Go back to parent.
882 : */
883 0 : UnlockReleaseBuffer(stack->buffer);
884 0 : xlocked = false;
885 0 : state.stack = stack = stack->parent;
886 0 : continue;
887 : }
888 : }
889 :
890 : /* now state.stack->(page, buffer and blkno) points to leaf page */
891 :
892 948612 : gistinserttuple(&state, stack, giststate, itup,
893 : InvalidOffsetNumber);
894 948600 : LockBuffer(stack->buffer, GIST_UNLOCK);
895 :
896 : /* Release any pins we might still hold before exiting */
897 3081912 : for (; stack; stack = stack->parent)
898 2133312 : ReleaseBuffer(stack->buffer);
899 948600 : break;
900 : }
901 : }
902 948600 : }
903 :
904 : /*
905 : * Traverse the tree to find path from root page to specified "child" block.
906 : *
907 : * returns a new insertion stack, starting from the parent of "child", up
908 : * to the root. *downlinkoffnum is set to the offset of the downlink in the
909 : * direct parent of child.
910 : *
911 : * To prevent deadlocks, this should lock only one page at a time.
912 : */
913 : static GISTInsertStack *
914 0 : gistFindPath(Relation r, BlockNumber child, OffsetNumber *downlinkoffnum)
915 : {
916 : Page page;
917 : Buffer buffer;
918 : OffsetNumber i,
919 : maxoff;
920 : ItemId iid;
921 : IndexTuple idxtuple;
922 : List *fifo;
923 : GISTInsertStack *top,
924 : *ptr;
925 : BlockNumber blkno;
926 :
927 0 : top = (GISTInsertStack *) palloc0(sizeof(GISTInsertStack));
928 0 : top->blkno = GIST_ROOT_BLKNO;
929 0 : top->downlinkoffnum = InvalidOffsetNumber;
930 :
931 0 : fifo = list_make1(top);
932 0 : while (fifo != NIL)
933 : {
934 : /* Get next page to visit */
935 0 : top = linitial(fifo);
936 0 : fifo = list_delete_first(fifo);
937 :
938 0 : buffer = ReadBuffer(r, top->blkno);
939 0 : LockBuffer(buffer, GIST_SHARE);
940 0 : gistcheckpage(r, buffer);
941 0 : page = (Page) BufferGetPage(buffer);
942 :
943 0 : if (GistPageIsLeaf(page))
944 : {
945 : /*
946 : * Because we scan the index top-down, all the rest of the pages
947 : * in the queue must be leaf pages as well.
948 : */
949 0 : UnlockReleaseBuffer(buffer);
950 0 : break;
951 : }
952 :
953 : /* currently, internal pages are never deleted */
954 : Assert(!GistPageIsDeleted(page));
955 :
956 0 : top->lsn = BufferGetLSNAtomic(buffer);
957 :
958 : /*
959 : * If F_FOLLOW_RIGHT is set, the page to the right doesn't have a
960 : * downlink. This should not normally happen..
961 : */
962 0 : if (GistFollowRight(page))
963 0 : elog(ERROR, "concurrent GiST page split was incomplete");
964 :
965 0 : if (top->parent && top->parent->lsn < GistPageGetNSN(page) &&
966 0 : GistPageGetOpaque(page)->rightlink != InvalidBlockNumber /* sanity check */ )
967 : {
968 : /*
969 : * Page was split while we looked elsewhere. We didn't see the
970 : * downlink to the right page when we scanned the parent, so add
971 : * it to the queue now.
972 : *
973 : * Put the right page ahead of the queue, so that we visit it
974 : * next. That's important, because if this is the lowest internal
975 : * level, just above leaves, we might already have queued up some
976 : * leaf pages, and we assume that there can't be any non-leaf
977 : * pages behind leaf pages.
978 : */
979 0 : ptr = (GISTInsertStack *) palloc0(sizeof(GISTInsertStack));
980 0 : ptr->blkno = GistPageGetOpaque(page)->rightlink;
981 0 : ptr->downlinkoffnum = InvalidOffsetNumber;
982 0 : ptr->parent = top->parent;
983 :
984 0 : fifo = lcons(ptr, fifo);
985 : }
986 :
987 0 : maxoff = PageGetMaxOffsetNumber(page);
988 :
989 0 : for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
990 : {
991 0 : iid = PageGetItemId(page, i);
992 0 : idxtuple = (IndexTuple) PageGetItem(page, iid);
993 0 : blkno = ItemPointerGetBlockNumber(&(idxtuple->t_tid));
994 0 : if (blkno == child)
995 : {
996 : /* Found it! */
997 0 : UnlockReleaseBuffer(buffer);
998 0 : *downlinkoffnum = i;
999 0 : return top;
1000 : }
1001 : else
1002 : {
1003 : /* Append this child to the list of pages to visit later */
1004 0 : ptr = (GISTInsertStack *) palloc0(sizeof(GISTInsertStack));
1005 0 : ptr->blkno = blkno;
1006 0 : ptr->downlinkoffnum = i;
1007 0 : ptr->parent = top;
1008 :
1009 0 : fifo = lappend(fifo, ptr);
1010 : }
1011 : }
1012 :
1013 0 : UnlockReleaseBuffer(buffer);
1014 : }
1015 :
1016 0 : elog(ERROR, "failed to re-find parent of a page in index \"%s\", block %u",
1017 : RelationGetRelationName(r), child);
1018 : return NULL; /* keep compiler quiet */
1019 : }
1020 :
1021 : /*
1022 : * Updates the stack so that child->parent is the correct parent of the
1023 : * child. child->parent must be exclusively locked on entry, and will
1024 : * remain so at exit, but it might not be the same page anymore.
1025 : */
1026 : static void
1027 24152 : gistFindCorrectParent(Relation r, GISTInsertStack *child, bool is_build)
1028 : {
1029 24152 : GISTInsertStack *parent = child->parent;
1030 : ItemId iid;
1031 : IndexTuple idxtuple;
1032 : OffsetNumber maxoff;
1033 : GISTInsertStack *ptr;
1034 :
1035 24152 : gistcheckpage(r, parent->buffer);
1036 24152 : parent->page = (Page) BufferGetPage(parent->buffer);
1037 24152 : maxoff = PageGetMaxOffsetNumber(parent->page);
1038 :
1039 : /* Check if the downlink is still where it was before */
1040 24152 : if (child->downlinkoffnum != InvalidOffsetNumber && child->downlinkoffnum <= maxoff)
1041 : {
1042 24152 : iid = PageGetItemId(parent->page, child->downlinkoffnum);
1043 24152 : idxtuple = (IndexTuple) PageGetItem(parent->page, iid);
1044 24152 : if (ItemPointerGetBlockNumber(&(idxtuple->t_tid)) == child->blkno)
1045 24152 : return; /* still there */
1046 : }
1047 :
1048 : /*
1049 : * The page has changed since we looked. During normal operation, every
1050 : * update of a page changes its LSN, so the LSN we memorized should have
1051 : * changed too. During index build, however, we don't WAL-log the changes
1052 : * until we have built the index, so the LSN doesn't change. There is no
1053 : * concurrent activity during index build, but we might have changed the
1054 : * parent ourselves.
1055 : */
1056 : Assert(parent->lsn != PageGetLSN(parent->page) || is_build);
1057 :
1058 : /*
1059 : * Scan the page to re-find the downlink. If the page was split, it might
1060 : * have moved to a different page, so follow the right links until we find
1061 : * it.
1062 : */
1063 : while (true)
1064 0 : {
1065 : OffsetNumber i;
1066 :
1067 0 : maxoff = PageGetMaxOffsetNumber(parent->page);
1068 0 : for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
1069 : {
1070 0 : iid = PageGetItemId(parent->page, i);
1071 0 : idxtuple = (IndexTuple) PageGetItem(parent->page, iid);
1072 0 : if (ItemPointerGetBlockNumber(&(idxtuple->t_tid)) == child->blkno)
1073 : {
1074 : /* yes!!, found */
1075 0 : child->downlinkoffnum = i;
1076 0 : return;
1077 : }
1078 : }
1079 :
1080 0 : parent->blkno = GistPageGetOpaque(parent->page)->rightlink;
1081 0 : parent->downlinkoffnum = InvalidOffsetNumber;
1082 0 : UnlockReleaseBuffer(parent->buffer);
1083 0 : if (parent->blkno == InvalidBlockNumber)
1084 : {
1085 : /*
1086 : * End of chain and still didn't find parent. It's a very-very
1087 : * rare situation when the root was split.
1088 : */
1089 0 : break;
1090 : }
1091 0 : parent->buffer = ReadBuffer(r, parent->blkno);
1092 0 : LockBuffer(parent->buffer, GIST_EXCLUSIVE);
1093 0 : gistcheckpage(r, parent->buffer);
1094 0 : parent->page = (Page) BufferGetPage(parent->buffer);
1095 : }
1096 :
1097 : /*
1098 : * awful!!, we need search tree to find parent ... , but before we should
1099 : * release all old parent
1100 : */
1101 :
1102 0 : ptr = child->parent->parent; /* child->parent already released above */
1103 0 : while (ptr)
1104 : {
1105 0 : ReleaseBuffer(ptr->buffer);
1106 0 : ptr = ptr->parent;
1107 : }
1108 :
1109 : /* ok, find new path */
1110 0 : ptr = parent = gistFindPath(r, child->blkno, &child->downlinkoffnum);
1111 :
1112 : /* read all buffers as expected by caller */
1113 : /* note we don't lock them or gistcheckpage them here! */
1114 0 : while (ptr)
1115 : {
1116 0 : ptr->buffer = ReadBuffer(r, ptr->blkno);
1117 0 : ptr->page = (Page) BufferGetPage(ptr->buffer);
1118 0 : ptr = ptr->parent;
1119 : }
1120 :
1121 : /* install new chain of parents to stack */
1122 0 : child->parent = parent;
1123 :
1124 : /* make recursive call to normal processing */
1125 0 : LockBuffer(child->parent->buffer, GIST_EXCLUSIVE);
1126 0 : gistFindCorrectParent(r, child, is_build);
1127 : }
1128 :
1129 : /*
1130 : * Form a downlink pointer for the page in 'buf'.
1131 : */
1132 : static IndexTuple
1133 0 : gistformdownlink(Relation rel, Buffer buf, GISTSTATE *giststate,
1134 : GISTInsertStack *stack, bool is_build)
1135 : {
1136 0 : Page page = BufferGetPage(buf);
1137 : OffsetNumber maxoff;
1138 : OffsetNumber offset;
1139 0 : IndexTuple downlink = NULL;
1140 :
1141 0 : maxoff = PageGetMaxOffsetNumber(page);
1142 0 : for (offset = FirstOffsetNumber; offset <= maxoff; offset = OffsetNumberNext(offset))
1143 : {
1144 : IndexTuple ituple = (IndexTuple)
1145 0 : PageGetItem(page, PageGetItemId(page, offset));
1146 :
1147 0 : if (downlink == NULL)
1148 0 : downlink = CopyIndexTuple(ituple);
1149 : else
1150 : {
1151 : IndexTuple newdownlink;
1152 :
1153 0 : newdownlink = gistgetadjusted(rel, downlink, ituple,
1154 : giststate);
1155 0 : if (newdownlink)
1156 0 : downlink = newdownlink;
1157 : }
1158 : }
1159 :
1160 : /*
1161 : * If the page is completely empty, we can't form a meaningful downlink
1162 : * for it. But we have to insert a downlink for the page. Any key will do,
1163 : * as long as its consistent with the downlink of parent page, so that we
1164 : * can legally insert it to the parent. A minimal one that matches as few
1165 : * scans as possible would be best, to keep scans from doing useless work,
1166 : * but we don't know how to construct that. So we just use the downlink of
1167 : * the original page that was split - that's as far from optimal as it can
1168 : * get but will do..
1169 : */
1170 0 : if (!downlink)
1171 : {
1172 : ItemId iid;
1173 :
1174 0 : LockBuffer(stack->parent->buffer, GIST_EXCLUSIVE);
1175 0 : gistFindCorrectParent(rel, stack, is_build);
1176 0 : iid = PageGetItemId(stack->parent->page, stack->downlinkoffnum);
1177 0 : downlink = (IndexTuple) PageGetItem(stack->parent->page, iid);
1178 0 : downlink = CopyIndexTuple(downlink);
1179 0 : LockBuffer(stack->parent->buffer, GIST_UNLOCK);
1180 : }
1181 :
1182 0 : ItemPointerSetBlockNumber(&(downlink->t_tid), BufferGetBlockNumber(buf));
1183 0 : GistTupleSetValid(downlink);
1184 :
1185 0 : return downlink;
1186 : }
1187 :
1188 :
1189 : /*
1190 : * Complete the incomplete split of state->stack->page.
1191 : */
1192 : static void
1193 0 : gistfixsplit(GISTInsertState *state, GISTSTATE *giststate)
1194 : {
1195 0 : GISTInsertStack *stack = state->stack;
1196 : Buffer buf;
1197 : Page page;
1198 0 : List *splitinfo = NIL;
1199 :
1200 0 : ereport(LOG,
1201 : (errmsg("fixing incomplete split in index \"%s\", block %u",
1202 : RelationGetRelationName(state->r), stack->blkno)));
1203 :
1204 : Assert(GistFollowRight(stack->page));
1205 : Assert(OffsetNumberIsValid(stack->downlinkoffnum));
1206 :
1207 0 : buf = stack->buffer;
1208 :
1209 : /*
1210 : * Read the chain of split pages, following the rightlinks. Construct a
1211 : * downlink tuple for each page.
1212 : */
1213 : for (;;)
1214 0 : {
1215 0 : GISTPageSplitInfo *si = palloc(sizeof(GISTPageSplitInfo));
1216 : IndexTuple downlink;
1217 :
1218 0 : page = BufferGetPage(buf);
1219 :
1220 : /* Form the new downlink tuples to insert to parent */
1221 0 : downlink = gistformdownlink(state->r, buf, giststate, stack, state->is_build);
1222 :
1223 0 : si->buf = buf;
1224 0 : si->downlink = downlink;
1225 :
1226 0 : splitinfo = lappend(splitinfo, si);
1227 :
1228 0 : if (GistFollowRight(page))
1229 : {
1230 : /* lock next page */
1231 0 : buf = ReadBuffer(state->r, GistPageGetOpaque(page)->rightlink);
1232 0 : LockBuffer(buf, GIST_EXCLUSIVE);
1233 : }
1234 : else
1235 0 : break;
1236 : }
1237 :
1238 : /* Insert the downlinks */
1239 0 : gistfinishsplit(state, stack, giststate, splitinfo, false);
1240 0 : }
1241 :
1242 : /*
1243 : * Insert or replace a tuple in stack->buffer. If 'oldoffnum' is valid, the
1244 : * tuple at 'oldoffnum' is replaced, otherwise the tuple is inserted as new.
1245 : * 'stack' represents the path from the root to the page being updated.
1246 : *
1247 : * The caller must hold an exclusive lock on stack->buffer. The lock is still
1248 : * held on return, but the page might not contain the inserted tuple if the
1249 : * page was split. The function returns true if the page was split, false
1250 : * otherwise.
1251 : */
1252 : static bool
1253 1619800 : gistinserttuple(GISTInsertState *state, GISTInsertStack *stack,
1254 : GISTSTATE *giststate, IndexTuple tuple, OffsetNumber oldoffnum)
1255 : {
1256 1619800 : return gistinserttuples(state, stack, giststate, &tuple, 1, oldoffnum,
1257 : InvalidBuffer, InvalidBuffer, false, false);
1258 : }
1259 :
1260 : /* ----------------
1261 : * An extended workhorse version of gistinserttuple(). This version allows
1262 : * inserting multiple tuples, or replacing a single tuple with multiple tuples.
1263 : * This is used to recursively update the downlinks in the parent when a page
1264 : * is split.
1265 : *
1266 : * If leftchild and rightchild are valid, we're inserting/replacing the
1267 : * downlink for rightchild, and leftchild is its left sibling. We clear the
1268 : * F_FOLLOW_RIGHT flag and update NSN on leftchild, atomically with the
1269 : * insertion of the downlink.
1270 : *
1271 : * To avoid holding locks for longer than necessary, when recursing up the
1272 : * tree to update the parents, the locking is a bit peculiar here. On entry,
1273 : * the caller must hold an exclusive lock on stack->buffer, as well as
1274 : * leftchild and rightchild if given. On return:
1275 : *
1276 : * - Lock on stack->buffer is released, if 'unlockbuf' is true. The page is
1277 : * always kept pinned, however.
1278 : * - Lock on 'leftchild' is released, if 'unlockleftchild' is true. The page
1279 : * is kept pinned.
1280 : * - Lock and pin on 'rightchild' are always released.
1281 : *
1282 : * Returns 'true' if the page had to be split. Note that if the page was
1283 : * split, the inserted/updated tuples might've been inserted to a right
1284 : * sibling of stack->buffer instead of stack->buffer itself.
1285 : */
1286 : static bool
1287 1643952 : gistinserttuples(GISTInsertState *state, GISTInsertStack *stack,
1288 : GISTSTATE *giststate,
1289 : IndexTuple *tuples, int ntup, OffsetNumber oldoffnum,
1290 : Buffer leftchild, Buffer rightchild,
1291 : bool unlockbuf, bool unlockleftchild)
1292 : {
1293 : List *splitinfo;
1294 : bool is_split;
1295 :
1296 : /*
1297 : * Check for any rw conflicts (in serializable isolation level) just
1298 : * before we intend to modify the page
1299 : */
1300 1643952 : CheckForSerializableConflictIn(state->r, NULL, BufferGetBlockNumber(stack->buffer));
1301 :
1302 : /* Insert the tuple(s) to the page, splitting the page if necessary */
1303 1643940 : is_split = gistplacetopage(state->r, state->freespace, giststate,
1304 : stack->buffer,
1305 : tuples, ntup,
1306 : oldoffnum, NULL,
1307 : leftchild,
1308 : &splitinfo,
1309 : true,
1310 : state->heapRel,
1311 1643940 : state->is_build);
1312 :
1313 : /*
1314 : * Before recursing up in case the page was split, release locks on the
1315 : * child pages. We don't need to keep them locked when updating the
1316 : * parent.
1317 : */
1318 1643940 : if (BufferIsValid(rightchild))
1319 24152 : UnlockReleaseBuffer(rightchild);
1320 1643940 : if (BufferIsValid(leftchild) && unlockleftchild)
1321 4846 : LockBuffer(leftchild, GIST_UNLOCK);
1322 :
1323 : /*
1324 : * If we had to split, insert/update the downlinks in the parent. If the
1325 : * caller requested us to release the lock on stack->buffer, tell
1326 : * gistfinishsplit() to do that as soon as it's safe to do so. If we
1327 : * didn't have to split, release it ourselves.
1328 : */
1329 1643940 : if (splitinfo)
1330 24096 : gistfinishsplit(state, stack, giststate, splitinfo, unlockbuf);
1331 1619844 : else if (unlockbuf)
1332 19250 : LockBuffer(stack->buffer, GIST_UNLOCK);
1333 :
1334 1643940 : return is_split;
1335 : }
1336 :
1337 : /*
1338 : * Finish an incomplete split by inserting/updating the downlinks in parent
1339 : * page. 'splitinfo' contains all the child pages involved in the split,
1340 : * from left-to-right.
1341 : *
1342 : * On entry, the caller must hold a lock on stack->buffer and all the child
1343 : * pages in 'splitinfo'. If 'unlockbuf' is true, the lock on stack->buffer is
1344 : * released on return. The child pages are always unlocked and unpinned.
1345 : */
1346 : static void
1347 24096 : gistfinishsplit(GISTInsertState *state, GISTInsertStack *stack,
1348 : GISTSTATE *giststate, List *splitinfo, bool unlockbuf)
1349 : {
1350 : GISTPageSplitInfo *right;
1351 : GISTPageSplitInfo *left;
1352 : IndexTuple tuples[2];
1353 :
1354 : /* A split always contains at least two halves */
1355 : Assert(list_length(splitinfo) >= 2);
1356 :
1357 : /*
1358 : * We need to insert downlinks for each new page, and update the downlink
1359 : * for the original (leftmost) page in the split. Begin at the rightmost
1360 : * page, inserting one downlink at a time until there's only two pages
1361 : * left. Finally insert the downlink for the last new page and update the
1362 : * downlink for the original page as one operation.
1363 : */
1364 24096 : LockBuffer(stack->parent->buffer, GIST_EXCLUSIVE);
1365 :
1366 : /*
1367 : * Insert downlinks for the siblings from right to left, until there are
1368 : * only two siblings left.
1369 : */
1370 24152 : for (int pos = list_length(splitinfo) - 1; pos > 1; pos--)
1371 : {
1372 56 : right = (GISTPageSplitInfo *) list_nth(splitinfo, pos);
1373 56 : left = (GISTPageSplitInfo *) list_nth(splitinfo, pos - 1);
1374 :
1375 56 : gistFindCorrectParent(state->r, stack, state->is_build);
1376 56 : if (gistinserttuples(state, stack->parent, giststate,
1377 : &right->downlink, 1,
1378 : InvalidOffsetNumber,
1379 : left->buf, right->buf, false, false))
1380 : {
1381 : /*
1382 : * If the parent page was split, the existing downlink might have
1383 : * moved.
1384 : */
1385 0 : stack->downlinkoffnum = InvalidOffsetNumber;
1386 : }
1387 : /* gistinserttuples() released the lock on right->buf. */
1388 : }
1389 :
1390 24096 : right = (GISTPageSplitInfo *) lsecond(splitinfo);
1391 24096 : left = (GISTPageSplitInfo *) linitial(splitinfo);
1392 :
1393 : /*
1394 : * Finally insert downlink for the remaining right page and update the
1395 : * downlink for the original page to not contain the tuples that were
1396 : * moved to the new pages.
1397 : */
1398 24096 : tuples[0] = left->downlink;
1399 24096 : tuples[1] = right->downlink;
1400 24096 : gistFindCorrectParent(state->r, stack, state->is_build);
1401 24096 : (void) gistinserttuples(state, stack->parent, giststate,
1402 : tuples, 2,
1403 24096 : stack->downlinkoffnum,
1404 : left->buf, right->buf,
1405 : true, /* Unlock parent */
1406 : unlockbuf /* Unlock stack->buffer if caller
1407 : * wants that */
1408 : );
1409 :
1410 : /*
1411 : * The downlink might have moved when we updated it. Even if the page
1412 : * wasn't split, because gistinserttuples() implements updating the old
1413 : * tuple by removing and re-inserting it!
1414 : */
1415 24096 : stack->downlinkoffnum = InvalidOffsetNumber;
1416 :
1417 : Assert(left->buf == stack->buffer);
1418 :
1419 : /*
1420 : * If we split the page because we had to adjust the downlink on an
1421 : * internal page, while descending the tree for inserting a new tuple,
1422 : * then this might no longer be the correct page for the new tuple. The
1423 : * downlink to this page might not cover the new tuple anymore, it might
1424 : * need to go to the newly-created right sibling instead. Tell the caller
1425 : * to walk back up the stack, to re-check at the parent which page to
1426 : * insert to.
1427 : *
1428 : * Normally, the LSN-NSN interlock during the tree descend would also
1429 : * detect that a concurrent split happened (by ourselves), and cause us to
1430 : * retry at the parent. But that mechanism doesn't work during index
1431 : * build, because we don't do WAL-logging, and don't update LSNs, during
1432 : * index build.
1433 : */
1434 24096 : stack->retry_from_parent = true;
1435 24096 : }
1436 :
1437 : /*
1438 : * gistSplit -- split a page in the tree and fill struct
1439 : * used for XLOG and real writes buffers. Function is recursive, ie
1440 : * it will split page until keys will fit in every page.
1441 : */
1442 : SplitPageLayout *
1443 26484 : gistSplit(Relation r,
1444 : Page page,
1445 : IndexTuple *itup, /* contains compressed entry */
1446 : int len,
1447 : GISTSTATE *giststate)
1448 : {
1449 : IndexTuple *lvectup,
1450 : *rvectup;
1451 : GistSplitVector v;
1452 : int i;
1453 26484 : SplitPageLayout *res = NULL;
1454 :
1455 : /* this should never recurse very deeply, but better safe than sorry */
1456 26484 : check_stack_depth();
1457 :
1458 : /* there's no point in splitting an empty page */
1459 : Assert(len > 0);
1460 :
1461 : /*
1462 : * If a single tuple doesn't fit on a page, no amount of splitting will
1463 : * help.
1464 : */
1465 26484 : if (len == 1)
1466 0 : ereport(ERROR,
1467 : (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
1468 : errmsg("index row size %zu exceeds maximum %zu for index \"%s\"",
1469 : IndexTupleSize(itup[0]), GiSTPageSize,
1470 : RelationGetRelationName(r))));
1471 :
1472 26484 : memset(v.spl_lisnull, true,
1473 26484 : sizeof(bool) * giststate->nonLeafTupdesc->natts);
1474 26484 : memset(v.spl_risnull, true,
1475 26484 : sizeof(bool) * giststate->nonLeafTupdesc->natts);
1476 26484 : gistSplitByKey(r, page, itup, len, giststate, &v, 0);
1477 :
1478 : /* form left and right vector */
1479 26484 : lvectup = (IndexTuple *) palloc(sizeof(IndexTuple) * (len + 1));
1480 26484 : rvectup = (IndexTuple *) palloc(sizeof(IndexTuple) * (len + 1));
1481 :
1482 1117080 : for (i = 0; i < v.splitVector.spl_nleft; i++)
1483 1090596 : lvectup[i] = itup[v.splitVector.spl_left[i] - 1];
1484 :
1485 1247726 : for (i = 0; i < v.splitVector.spl_nright; i++)
1486 1221242 : rvectup[i] = itup[v.splitVector.spl_right[i] - 1];
1487 :
1488 : /* finalize splitting (may need another split) */
1489 26484 : if (!gistfitpage(rvectup, v.splitVector.spl_nright))
1490 : {
1491 596 : res = gistSplit(r, page, rvectup, v.splitVector.spl_nright, giststate);
1492 : }
1493 : else
1494 : {
1495 25888 : ROTATEDIST(res);
1496 25888 : res->block.num = v.splitVector.spl_nright;
1497 25888 : res->list = gistfillitupvec(rvectup, v.splitVector.spl_nright, &(res->lenlist));
1498 25888 : res->itup = gistFormTuple(giststate, r, v.spl_rattr, v.spl_risnull, false);
1499 : }
1500 :
1501 26484 : if (!gistfitpage(lvectup, v.splitVector.spl_nleft))
1502 : {
1503 : SplitPageLayout *resptr,
1504 : *subres;
1505 :
1506 330 : resptr = subres = gistSplit(r, page, lvectup, v.splitVector.spl_nleft, giststate);
1507 :
1508 : /* install on list's tail */
1509 822 : while (resptr->next)
1510 492 : resptr = resptr->next;
1511 :
1512 330 : resptr->next = res;
1513 330 : res = subres;
1514 : }
1515 : else
1516 : {
1517 26154 : ROTATEDIST(res);
1518 26154 : res->block.num = v.splitVector.spl_nleft;
1519 26154 : res->list = gistfillitupvec(lvectup, v.splitVector.spl_nleft, &(res->lenlist));
1520 26154 : res->itup = gistFormTuple(giststate, r, v.spl_lattr, v.spl_lisnull, false);
1521 : }
1522 :
1523 26484 : return res;
1524 : }
1525 :
1526 : /*
1527 : * Create a GISTSTATE and fill it with information about the index
1528 : */
1529 : GISTSTATE *
1530 9164 : initGISTstate(Relation index)
1531 : {
1532 : GISTSTATE *giststate;
1533 : MemoryContext scanCxt;
1534 : MemoryContext oldCxt;
1535 : int i;
1536 :
1537 : /* safety check to protect fixed-size arrays in GISTSTATE */
1538 9164 : if (index->rd_att->natts > INDEX_MAX_KEYS)
1539 0 : elog(ERROR, "numberOfAttributes %d > %d",
1540 : index->rd_att->natts, INDEX_MAX_KEYS);
1541 :
1542 : /* Create the memory context that will hold the GISTSTATE */
1543 9164 : scanCxt = AllocSetContextCreate(CurrentMemoryContext,
1544 : "GiST scan context",
1545 : ALLOCSET_DEFAULT_SIZES);
1546 9164 : oldCxt = MemoryContextSwitchTo(scanCxt);
1547 :
1548 : /* Create and fill in the GISTSTATE */
1549 9164 : giststate = (GISTSTATE *) palloc(sizeof(GISTSTATE));
1550 :
1551 9164 : giststate->scanCxt = scanCxt;
1552 9164 : giststate->tempCxt = scanCxt; /* caller must change this if needed */
1553 9164 : giststate->leafTupdesc = index->rd_att;
1554 :
1555 : /*
1556 : * The truncated tupdesc for non-leaf index tuples, which doesn't contain
1557 : * the INCLUDE attributes.
1558 : *
1559 : * It is used to form tuples during tuple adjustment and page split.
1560 : * B-tree creates shortened tuple descriptor for every truncated tuple,
1561 : * because it is doing this less often: it does not have to form truncated
1562 : * tuples during page split. Also, B-tree is not adjusting tuples on
1563 : * internal pages the way GiST does.
1564 : */
1565 18328 : giststate->nonLeafTupdesc = CreateTupleDescTruncatedCopy(index->rd_att,
1566 9164 : IndexRelationGetNumberOfKeyAttributes(index));
1567 :
1568 24248 : for (i = 0; i < IndexRelationGetNumberOfKeyAttributes(index); i++)
1569 : {
1570 15084 : fmgr_info_copy(&(giststate->consistentFn[i]),
1571 15084 : index_getprocinfo(index, i + 1, GIST_CONSISTENT_PROC),
1572 : scanCxt);
1573 15084 : fmgr_info_copy(&(giststate->unionFn[i]),
1574 15084 : index_getprocinfo(index, i + 1, GIST_UNION_PROC),
1575 : scanCxt);
1576 :
1577 : /* opclasses are not required to provide a Compress method */
1578 15084 : if (OidIsValid(index_getprocid(index, i + 1, GIST_COMPRESS_PROC)))
1579 5386 : fmgr_info_copy(&(giststate->compressFn[i]),
1580 5386 : index_getprocinfo(index, i + 1, GIST_COMPRESS_PROC),
1581 : scanCxt);
1582 : else
1583 9698 : giststate->compressFn[i].fn_oid = InvalidOid;
1584 :
1585 : /* opclasses are not required to provide a Decompress method */
1586 15084 : if (OidIsValid(index_getprocid(index, i + 1, GIST_DECOMPRESS_PROC)))
1587 1594 : fmgr_info_copy(&(giststate->decompressFn[i]),
1588 1594 : index_getprocinfo(index, i + 1, GIST_DECOMPRESS_PROC),
1589 : scanCxt);
1590 : else
1591 13490 : giststate->decompressFn[i].fn_oid = InvalidOid;
1592 :
1593 15084 : fmgr_info_copy(&(giststate->penaltyFn[i]),
1594 15084 : index_getprocinfo(index, i + 1, GIST_PENALTY_PROC),
1595 : scanCxt);
1596 15084 : fmgr_info_copy(&(giststate->picksplitFn[i]),
1597 15084 : index_getprocinfo(index, i + 1, GIST_PICKSPLIT_PROC),
1598 : scanCxt);
1599 15084 : fmgr_info_copy(&(giststate->equalFn[i]),
1600 15084 : index_getprocinfo(index, i + 1, GIST_EQUAL_PROC),
1601 : scanCxt);
1602 :
1603 : /* opclasses are not required to provide a Distance method */
1604 15084 : if (OidIsValid(index_getprocid(index, i + 1, GIST_DISTANCE_PROC)))
1605 1904 : fmgr_info_copy(&(giststate->distanceFn[i]),
1606 1904 : index_getprocinfo(index, i + 1, GIST_DISTANCE_PROC),
1607 : scanCxt);
1608 : else
1609 13180 : giststate->distanceFn[i].fn_oid = InvalidOid;
1610 :
1611 : /* opclasses are not required to provide a Fetch method */
1612 15084 : if (OidIsValid(index_getprocid(index, i + 1, GIST_FETCH_PROC)))
1613 1362 : fmgr_info_copy(&(giststate->fetchFn[i]),
1614 1362 : index_getprocinfo(index, i + 1, GIST_FETCH_PROC),
1615 : scanCxt);
1616 : else
1617 13722 : giststate->fetchFn[i].fn_oid = InvalidOid;
1618 :
1619 : /*
1620 : * If the index column has a specified collation, we should honor that
1621 : * while doing comparisons. However, we may have a collatable storage
1622 : * type for a noncollatable indexed data type. If there's no index
1623 : * collation then specify default collation in case the support
1624 : * functions need collation. This is harmless if the support
1625 : * functions don't care about collation, so we just do it
1626 : * unconditionally. (We could alternatively call get_typcollation,
1627 : * but that seems like expensive overkill --- there aren't going to be
1628 : * any cases where a GiST storage type has a nondefault collation.)
1629 : */
1630 15084 : if (OidIsValid(index->rd_indcollation[i]))
1631 194 : giststate->supportCollation[i] = index->rd_indcollation[i];
1632 : else
1633 14890 : giststate->supportCollation[i] = DEFAULT_COLLATION_OID;
1634 : }
1635 :
1636 : /* No opclass information for INCLUDE attributes */
1637 9666 : for (; i < index->rd_att->natts; i++)
1638 : {
1639 502 : giststate->consistentFn[i].fn_oid = InvalidOid;
1640 502 : giststate->unionFn[i].fn_oid = InvalidOid;
1641 502 : giststate->compressFn[i].fn_oid = InvalidOid;
1642 502 : giststate->decompressFn[i].fn_oid = InvalidOid;
1643 502 : giststate->penaltyFn[i].fn_oid = InvalidOid;
1644 502 : giststate->picksplitFn[i].fn_oid = InvalidOid;
1645 502 : giststate->equalFn[i].fn_oid = InvalidOid;
1646 502 : giststate->distanceFn[i].fn_oid = InvalidOid;
1647 502 : giststate->fetchFn[i].fn_oid = InvalidOid;
1648 502 : giststate->supportCollation[i] = InvalidOid;
1649 : }
1650 :
1651 9164 : MemoryContextSwitchTo(oldCxt);
1652 :
1653 9164 : return giststate;
1654 : }
1655 :
1656 : void
1657 7040 : freeGISTstate(GISTSTATE *giststate)
1658 : {
1659 : /* It's sufficient to delete the scanCxt */
1660 7040 : MemoryContextDelete(giststate->scanCxt);
1661 7040 : }
1662 :
1663 : /*
1664 : * gistprunepage() -- try to remove LP_DEAD items from the given page.
1665 : * Function assumes that buffer is exclusively locked.
1666 : */
1667 : static void
1668 0 : gistprunepage(Relation rel, Page page, Buffer buffer, Relation heapRel)
1669 : {
1670 : OffsetNumber deletable[MaxIndexTuplesPerPage];
1671 0 : int ndeletable = 0;
1672 : OffsetNumber offnum,
1673 : maxoff;
1674 :
1675 : Assert(GistPageIsLeaf(page));
1676 :
1677 : /*
1678 : * Scan over all items to see which ones need to be deleted according to
1679 : * LP_DEAD flags.
1680 : */
1681 0 : maxoff = PageGetMaxOffsetNumber(page);
1682 0 : for (offnum = FirstOffsetNumber;
1683 : offnum <= maxoff;
1684 0 : offnum = OffsetNumberNext(offnum))
1685 : {
1686 0 : ItemId itemId = PageGetItemId(page, offnum);
1687 :
1688 0 : if (ItemIdIsDead(itemId))
1689 0 : deletable[ndeletable++] = offnum;
1690 : }
1691 :
1692 0 : if (ndeletable > 0)
1693 : {
1694 0 : TransactionId snapshotConflictHorizon = InvalidTransactionId;
1695 :
1696 0 : if (XLogStandbyInfoActive() && RelationNeedsWAL(rel))
1697 : snapshotConflictHorizon =
1698 0 : index_compute_xid_horizon_for_tuples(rel, heapRel, buffer,
1699 : deletable, ndeletable);
1700 :
1701 0 : START_CRIT_SECTION();
1702 :
1703 0 : PageIndexMultiDelete(page, deletable, ndeletable);
1704 :
1705 : /*
1706 : * Mark the page as not containing any LP_DEAD items. This is not
1707 : * certainly true (there might be some that have recently been marked,
1708 : * but weren't included in our target-item list), but it will almost
1709 : * always be true and it doesn't seem worth an additional page scan to
1710 : * check it. Remember that F_HAS_GARBAGE is only a hint anyway.
1711 : */
1712 0 : GistClearPageHasGarbage(page);
1713 :
1714 0 : MarkBufferDirty(buffer);
1715 :
1716 : /* XLOG stuff */
1717 0 : if (RelationNeedsWAL(rel))
1718 0 : {
1719 : XLogRecPtr recptr;
1720 :
1721 0 : recptr = gistXLogDelete(buffer,
1722 : deletable, ndeletable,
1723 : snapshotConflictHorizon,
1724 : heapRel);
1725 :
1726 0 : PageSetLSN(page, recptr);
1727 : }
1728 : else
1729 0 : PageSetLSN(page, gistGetFakeLSN(rel));
1730 :
1731 0 : END_CRIT_SECTION();
1732 : }
1733 :
1734 : /*
1735 : * Note: if we didn't find any LP_DEAD items, then the page's
1736 : * F_HAS_GARBAGE hint bit is falsely set. We do not bother expending a
1737 : * separate write to clear it, however. We will clear it when we split
1738 : * the page.
1739 : */
1740 0 : }
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