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1 : : /*-------------------------------------------------------------------------
2 : : *
3 : : * nbtpage.c
4 : : * BTree-specific page management code for the Postgres btree access
5 : : * method.
6 : : *
7 : : * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group
8 : : * Portions Copyright (c) 1994, Regents of the University of California
9 : : *
10 : : *
11 : : * IDENTIFICATION
12 : : * src/backend/access/nbtree/nbtpage.c
13 : : *
14 : : * NOTES
15 : : * Postgres btree pages look like ordinary relation pages. The opaque
16 : : * data at high addresses includes pointers to left and right siblings
17 : : * and flag data describing page state. The first page in a btree, page
18 : : * zero, is special -- it stores meta-information describing the tree.
19 : : * Pages one and higher store the actual tree data.
20 : : *
21 : : *-------------------------------------------------------------------------
22 : : */
23 : : #include "postgres.h"
24 : :
25 : : #include "access/nbtree.h"
26 : : #include "access/nbtxlog.h"
27 : : #include "access/tableam.h"
28 : : #include "access/transam.h"
29 : : #include "access/xlog.h"
30 : : #include "access/xloginsert.h"
31 : : #include "common/int.h"
32 : : #include "miscadmin.h"
33 : : #include "storage/indexfsm.h"
34 : : #include "storage/predicate.h"
35 : : #include "storage/procarray.h"
36 : : #include "utils/injection_point.h"
37 : : #include "utils/memdebug.h"
38 : : #include "utils/memutils.h"
39 : : #include "utils/snapmgr.h"
40 : :
41 : : static BTMetaPageData *_bt_getmeta(Relation rel, Buffer metabuf);
42 : : static void _bt_delitems_delete(Relation rel, Buffer buf,
43 : : TransactionId snapshotConflictHorizon,
44 : : bool isCatalogRel,
45 : : OffsetNumber *deletable, int ndeletable,
46 : : BTVacuumPosting *updatable, int nupdatable);
47 : : static char *_bt_delitems_update(BTVacuumPosting *updatable, int nupdatable,
48 : : OffsetNumber *updatedoffsets,
49 : : Size *updatedbuflen, bool needswal);
50 : : static bool _bt_mark_page_halfdead(Relation rel, Relation heaprel,
51 : : Buffer leafbuf, BTStack stack);
52 : : static bool _bt_unlink_halfdead_page(Relation rel, Buffer leafbuf,
53 : : BlockNumber scanblkno,
54 : : bool *rightsib_empty,
55 : : BTVacState *vstate);
56 : : static bool _bt_lock_subtree_parent(Relation rel, Relation heaprel,
57 : : BlockNumber child, BTStack stack,
58 : : Buffer *subtreeparent, OffsetNumber *poffset,
59 : : BlockNumber *topparent,
60 : : BlockNumber *topparentrightsib);
61 : : static void _bt_pendingfsm_add(BTVacState *vstate, BlockNumber target,
62 : : FullTransactionId safexid);
63 : :
64 : : /*
65 : : * _bt_initmetapage() -- Fill a page buffer with a correct metapage image
66 : : */
67 : : void
68 : 3712 : _bt_initmetapage(Page page, BlockNumber rootbknum, uint32 level,
69 : : bool allequalimage)
70 : : {
71 : 3712 : BTMetaPageData *metad;
72 : 3712 : BTPageOpaque metaopaque;
73 : :
74 : 3712 : _bt_pageinit(page, BLCKSZ);
75 : :
76 : 3712 : metad = BTPageGetMeta(page);
77 : 3712 : metad->btm_magic = BTREE_MAGIC;
78 : 3712 : metad->btm_version = BTREE_VERSION;
79 : 3712 : metad->btm_root = rootbknum;
80 : 3712 : metad->btm_level = level;
81 : 3712 : metad->btm_fastroot = rootbknum;
82 : 3712 : metad->btm_fastlevel = level;
83 : 3712 : metad->btm_last_cleanup_num_delpages = 0;
84 : 3712 : metad->btm_last_cleanup_num_heap_tuples = -1.0;
85 : 3712 : metad->btm_allequalimage = allequalimage;
86 : :
87 : 3712 : metaopaque = BTPageGetOpaque(page);
88 : 3712 : metaopaque->btpo_flags = BTP_META;
89 : :
90 : : /*
91 : : * Set pd_lower just past the end of the metadata. This is essential,
92 : : * because without doing so, metadata will be lost if xlog.c compresses
93 : : * the page.
94 : : */
95 : 3712 : ((PageHeader) page)->pd_lower =
96 : 3712 : ((char *) metad + sizeof(BTMetaPageData)) - (char *) page;
97 : 3712 : }
98 : :
99 : : /*
100 : : * _bt_upgrademetapage() -- Upgrade a meta-page from an old format to version
101 : : * 3, the last version that can be updated without broadly affecting
102 : : * on-disk compatibility. (A REINDEX is required to upgrade to v4.)
103 : : *
104 : : * This routine does purely in-memory image upgrade. Caller is
105 : : * responsible for locking, WAL-logging etc.
106 : : */
107 : : void
108 : 0 : _bt_upgrademetapage(Page page)
109 : : {
110 : 0 : BTMetaPageData *metad;
111 : 0 : BTPageOpaque metaopaque PG_USED_FOR_ASSERTS_ONLY;
112 : :
113 : 0 : metad = BTPageGetMeta(page);
114 : 0 : metaopaque = BTPageGetOpaque(page);
115 : :
116 : : /* It must be really a meta page of upgradable version */
117 [ # # ]: 0 : Assert(metaopaque->btpo_flags & BTP_META);
118 [ # # ]: 0 : Assert(metad->btm_version < BTREE_NOVAC_VERSION);
119 [ # # ]: 0 : Assert(metad->btm_version >= BTREE_MIN_VERSION);
120 : :
121 : : /* Set version number and fill extra fields added into version 3 */
122 : 0 : metad->btm_version = BTREE_NOVAC_VERSION;
123 : 0 : metad->btm_last_cleanup_num_delpages = 0;
124 : 0 : metad->btm_last_cleanup_num_heap_tuples = -1.0;
125 : : /* Only a REINDEX can set this field */
126 [ # # ]: 0 : Assert(!metad->btm_allequalimage);
127 : 0 : metad->btm_allequalimage = false;
128 : :
129 : : /* Adjust pd_lower (see _bt_initmetapage() for details) */
130 : 0 : ((PageHeader) page)->pd_lower =
131 : 0 : ((char *) metad + sizeof(BTMetaPageData)) - (char *) page;
132 : 0 : }
133 : :
134 : : /*
135 : : * Get metadata from share-locked buffer containing metapage, while performing
136 : : * standard sanity checks.
137 : : *
138 : : * Callers that cache data returned here in local cache should note that an
139 : : * on-the-fly upgrade using _bt_upgrademetapage() can change the version field
140 : : * and BTREE_NOVAC_VERSION specific fields without invalidating local cache.
141 : : */
142 : : static BTMetaPageData *
143 : 88453 : _bt_getmeta(Relation rel, Buffer metabuf)
144 : : {
145 : 88453 : Page metapg;
146 : 88453 : BTPageOpaque metaopaque;
147 : 88453 : BTMetaPageData *metad;
148 : :
149 : 88453 : metapg = BufferGetPage(metabuf);
150 : 88453 : metaopaque = BTPageGetOpaque(metapg);
151 : 88453 : metad = BTPageGetMeta(metapg);
152 : :
153 : : /* sanity-check the metapage */
154 [ + - ]: 88453 : if (!P_ISMETA(metaopaque) ||
155 : 88453 : metad->btm_magic != BTREE_MAGIC)
156 [ # # # # ]: 0 : ereport(ERROR,
157 : : (errcode(ERRCODE_INDEX_CORRUPTED),
158 : : errmsg("index \"%s\" is not a btree",
159 : : RelationGetRelationName(rel))));
160 : :
161 [ + - ]: 88453 : if (metad->btm_version < BTREE_MIN_VERSION ||
162 : 88453 : metad->btm_version > BTREE_VERSION)
163 [ # # # # ]: 0 : ereport(ERROR,
164 : : (errcode(ERRCODE_INDEX_CORRUPTED),
165 : : errmsg("version mismatch in index \"%s\": file version %d, "
166 : : "current version %d, minimal supported version %d",
167 : : RelationGetRelationName(rel),
168 : : metad->btm_version, BTREE_VERSION, BTREE_MIN_VERSION)));
169 : :
170 : 176906 : return metad;
171 : 88453 : }
172 : :
173 : : /*
174 : : * _bt_vacuum_needs_cleanup() -- Checks if index needs cleanup
175 : : *
176 : : * Called by btvacuumcleanup when btbulkdelete was never called because no
177 : : * index tuples needed to be deleted.
178 : : */
179 : : bool
180 : 469 : _bt_vacuum_needs_cleanup(Relation rel)
181 : : {
182 : 469 : Buffer metabuf;
183 : 469 : Page metapg;
184 : 469 : BTMetaPageData *metad;
185 : 469 : uint32 btm_version;
186 : 469 : BlockNumber prev_num_delpages;
187 : :
188 : : /*
189 : : * Copy details from metapage to local variables quickly.
190 : : *
191 : : * Note that we deliberately avoid using cached version of metapage here.
192 : : */
193 : 469 : metabuf = _bt_getbuf(rel, BTREE_METAPAGE, BT_READ);
194 : 469 : metapg = BufferGetPage(metabuf);
195 : 469 : metad = BTPageGetMeta(metapg);
196 : 469 : btm_version = metad->btm_version;
197 : :
198 [ - + ]: 469 : if (btm_version < BTREE_NOVAC_VERSION)
199 : : {
200 : : /*
201 : : * Metapage needs to be dynamically upgraded to store fields that are
202 : : * only present when btm_version >= BTREE_NOVAC_VERSION
203 : : */
204 : 0 : _bt_relbuf(rel, metabuf);
205 : 0 : return true;
206 : : }
207 : :
208 : 469 : prev_num_delpages = metad->btm_last_cleanup_num_delpages;
209 : 469 : _bt_relbuf(rel, metabuf);
210 : :
211 : : /*
212 : : * Trigger cleanup in rare cases where prev_num_delpages exceeds 5% of the
213 : : * total size of the index. We can reasonably expect (though are not
214 : : * guaranteed) to be able to recycle this many pages if we decide to do a
215 : : * btvacuumscan call during the ongoing btvacuumcleanup. For further
216 : : * details see the nbtree/README section on placing deleted pages in the
217 : : * FSM.
218 : : */
219 [ + + - + ]: 469 : if (prev_num_delpages > 0 &&
220 : 1 : prev_num_delpages > RelationGetNumberOfBlocks(rel) / 20)
221 : 1 : return true;
222 : :
223 : 468 : return false;
224 : 469 : }
225 : :
226 : : /*
227 : : * _bt_set_cleanup_info() -- Update metapage for btvacuumcleanup.
228 : : *
229 : : * Called at the end of btvacuumcleanup, when num_delpages value has been
230 : : * finalized.
231 : : */
232 : : void
233 : 107 : _bt_set_cleanup_info(Relation rel, BlockNumber num_delpages)
234 : : {
235 : 107 : Buffer metabuf;
236 : 107 : Page metapg;
237 : 107 : BTMetaPageData *metad;
238 : :
239 : : /*
240 : : * On-disk compatibility note: The btm_last_cleanup_num_delpages metapage
241 : : * field started out as a TransactionId field called btm_oldest_btpo_xact.
242 : : * Both "versions" are just uint32 fields. It was convenient to repurpose
243 : : * the field when we began to use 64-bit XIDs in deleted pages.
244 : : *
245 : : * It's possible that a pg_upgrade'd database will contain an XID value in
246 : : * what is now recognized as the metapage's btm_last_cleanup_num_delpages
247 : : * field. _bt_vacuum_needs_cleanup() may even believe that this value
248 : : * indicates that there are lots of pages that it needs to recycle, when
249 : : * in reality there are only one or two. The worst that can happen is
250 : : * that there will be a call to btvacuumscan a little earlier, which will
251 : : * set btm_last_cleanup_num_delpages to a sane value when we're called.
252 : : *
253 : : * Note also that the metapage's btm_last_cleanup_num_heap_tuples field is
254 : : * no longer used as of PostgreSQL 14. We set it to -1.0 on rewrite, just
255 : : * to be consistent.
256 : : */
257 : 107 : metabuf = _bt_getbuf(rel, BTREE_METAPAGE, BT_READ);
258 : 107 : metapg = BufferGetPage(metabuf);
259 : 107 : metad = BTPageGetMeta(metapg);
260 : :
261 : : /* Don't miss chance to upgrade index/metapage when BTREE_MIN_VERSION */
262 [ + - + + ]: 107 : if (metad->btm_version >= BTREE_NOVAC_VERSION &&
263 : 107 : metad->btm_last_cleanup_num_delpages == num_delpages)
264 : : {
265 : : /* Usually means index continues to have num_delpages of 0 */
266 : 94 : _bt_relbuf(rel, metabuf);
267 : 94 : return;
268 : : }
269 : :
270 : : /* trade in our read lock for a write lock */
271 : 13 : _bt_unlockbuf(rel, metabuf);
272 : 13 : _bt_lockbuf(rel, metabuf, BT_WRITE);
273 : :
274 : 13 : START_CRIT_SECTION();
275 : :
276 : : /* upgrade meta-page if needed */
277 [ + - ]: 13 : if (metad->btm_version < BTREE_NOVAC_VERSION)
278 : 0 : _bt_upgrademetapage(metapg);
279 : :
280 : : /* update cleanup-related information */
281 : 13 : metad->btm_last_cleanup_num_delpages = num_delpages;
282 : 13 : metad->btm_last_cleanup_num_heap_tuples = -1.0;
283 : 13 : MarkBufferDirty(metabuf);
284 : :
285 : : /* write wal record if needed */
286 [ + - + - : 13 : if (RelationNeedsWAL(rel))
+ - - + ]
287 : : {
288 : 13 : xl_btree_metadata md;
289 : 13 : XLogRecPtr recptr;
290 : :
291 : 13 : XLogBeginInsert();
292 : 13 : XLogRegisterBuffer(0, metabuf, REGBUF_WILL_INIT | REGBUF_STANDARD);
293 : :
294 [ + - ]: 13 : Assert(metad->btm_version >= BTREE_NOVAC_VERSION);
295 : 13 : md.version = metad->btm_version;
296 : 13 : md.root = metad->btm_root;
297 : 13 : md.level = metad->btm_level;
298 : 13 : md.fastroot = metad->btm_fastroot;
299 : 13 : md.fastlevel = metad->btm_fastlevel;
300 : 13 : md.last_cleanup_num_delpages = num_delpages;
301 : 13 : md.allequalimage = metad->btm_allequalimage;
302 : :
303 : 13 : XLogRegisterBufData(0, &md, sizeof(xl_btree_metadata));
304 : :
305 : 13 : recptr = XLogInsert(RM_BTREE_ID, XLOG_BTREE_META_CLEANUP);
306 : :
307 : 13 : PageSetLSN(metapg, recptr);
308 : 13 : }
309 : :
310 [ + - ]: 13 : END_CRIT_SECTION();
311 : :
312 : 13 : _bt_relbuf(rel, metabuf);
313 [ - + ]: 107 : }
314 : :
315 : : /*
316 : : * _bt_getroot() -- Get the root page of the btree.
317 : : *
318 : : * Since the root page can move around the btree file, we have to read
319 : : * its location from the metadata page, and then read the root page
320 : : * itself. If no root page exists yet, we have to create one.
321 : : *
322 : : * The access type parameter (BT_READ or BT_WRITE) controls whether
323 : : * a new root page will be created or not. If access = BT_READ,
324 : : * and no root page exists, we just return InvalidBuffer. For
325 : : * BT_WRITE, we try to create the root page if it doesn't exist.
326 : : * NOTE that the returned root page will have only a read lock set
327 : : * on it even if access = BT_WRITE!
328 : : *
329 : : * If access = BT_WRITE, heaprel must be set; otherwise caller can just
330 : : * pass NULL. See _bt_allocbuf for an explanation.
331 : : *
332 : : * The returned page is not necessarily the true root --- it could be
333 : : * a "fast root" (a page that is alone in its level due to deletions).
334 : : * Also, if the root page is split while we are "in flight" to it,
335 : : * what we will return is the old root, which is now just the leftmost
336 : : * page on a probably-not-very-wide level. For most purposes this is
337 : : * as good as or better than the true root, so we do not bother to
338 : : * insist on finding the true root. We do, however, guarantee to
339 : : * return a live (not deleted or half-dead) page.
340 : : *
341 : : * On successful return, the root page is pinned and read-locked.
342 : : * The metadata page is not locked or pinned on exit.
343 : : */
344 : : Buffer
345 : 1845721 : _bt_getroot(Relation rel, Relation heaprel, int access)
346 : : {
347 : 1845721 : Buffer metabuf;
348 : 1845721 : Buffer rootbuf;
349 : 1845721 : Page rootpage;
350 : 1845721 : BTPageOpaque rootopaque;
351 : 1845721 : BlockNumber rootblkno;
352 : 1845721 : uint32 rootlevel;
353 : 1845721 : BTMetaPageData *metad;
354 : :
355 [ + + + - ]: 1845721 : Assert(access == BT_READ || heaprel != NULL);
356 : :
357 : : /*
358 : : * Try to use previously-cached metapage data to find the root. This
359 : : * normally saves one buffer access per index search, which is a very
360 : : * helpful savings in bufmgr traffic and hence contention.
361 : : */
362 [ + + ]: 1845721 : if (rel->rd_amcache != NULL)
363 : : {
364 : 1817469 : metad = (BTMetaPageData *) rel->rd_amcache;
365 : : /* We shouldn't have cached it if any of these fail */
366 [ + - ]: 1817469 : Assert(metad->btm_magic == BTREE_MAGIC);
367 [ + - ]: 1817469 : Assert(metad->btm_version >= BTREE_MIN_VERSION);
368 [ + - ]: 1817469 : Assert(metad->btm_version <= BTREE_VERSION);
369 [ + + + - ]: 1817469 : Assert(!metad->btm_allequalimage ||
370 : : metad->btm_version > BTREE_NOVAC_VERSION);
371 [ + - ]: 1817469 : Assert(metad->btm_root != P_NONE);
372 : :
373 : 1817469 : rootblkno = metad->btm_fastroot;
374 [ + - ]: 1817469 : Assert(rootblkno != P_NONE);
375 : 1817469 : rootlevel = metad->btm_fastlevel;
376 : :
377 : 1817469 : rootbuf = _bt_getbuf(rel, rootblkno, BT_READ);
378 : 1817469 : rootpage = BufferGetPage(rootbuf);
379 : 1817469 : rootopaque = BTPageGetOpaque(rootpage);
380 : :
381 : : /*
382 : : * Since the cache might be stale, we check the page more carefully
383 : : * here than normal. We *must* check that it's not deleted. If it's
384 : : * not alone on its level, then we reject too --- this may be overly
385 : : * paranoid but better safe than sorry. Note we don't check P_ISROOT,
386 : : * because that's not set in a "fast root".
387 : : */
388 [ + - ]: 1817469 : if (!P_IGNORE(rootopaque) &&
389 [ + - ]: 1817469 : rootopaque->btpo_level == rootlevel &&
390 [ + - + + ]: 1817469 : P_LEFTMOST(rootopaque) &&
391 : 1817469 : P_RIGHTMOST(rootopaque))
392 : : {
393 : : /* OK, accept cached page as the root */
394 : 1817374 : return rootbuf;
395 : : }
396 : 95 : _bt_relbuf(rel, rootbuf);
397 : : /* Cache is stale, throw it away */
398 [ - + ]: 95 : if (rel->rd_amcache)
399 : 95 : pfree(rel->rd_amcache);
400 : 95 : rel->rd_amcache = NULL;
401 : 95 : }
402 : :
403 : 28347 : metabuf = _bt_getbuf(rel, BTREE_METAPAGE, BT_READ);
404 : 28347 : metad = _bt_getmeta(rel, metabuf);
405 : :
406 : : /* if no root page initialized yet, do it */
407 [ + + ]: 28347 : if (metad->btm_root == P_NONE)
408 : : {
409 : 28242 : Page metapg;
410 : :
411 : : /* If access = BT_READ, caller doesn't want us to create root yet */
412 [ + + ]: 28242 : if (access == BT_READ)
413 : : {
414 : 27545 : _bt_relbuf(rel, metabuf);
415 : 27545 : return InvalidBuffer;
416 : : }
417 : :
418 : : /* trade in our read lock for a write lock */
419 : 697 : _bt_unlockbuf(rel, metabuf);
420 : 697 : _bt_lockbuf(rel, metabuf, BT_WRITE);
421 : :
422 : : /*
423 : : * Race condition: if someone else initialized the metadata between
424 : : * the time we released the read lock and acquired the write lock, we
425 : : * must avoid doing it again.
426 : : */
427 [ - + ]: 697 : if (metad->btm_root != P_NONE)
428 : : {
429 : : /*
430 : : * Metadata initialized by someone else. In order to guarantee no
431 : : * deadlocks, we have to release the metadata page and start all
432 : : * over again. (Is that really true? But it's hardly worth trying
433 : : * to optimize this case.)
434 : : */
435 : 0 : _bt_relbuf(rel, metabuf);
436 : 0 : return _bt_getroot(rel, heaprel, access);
437 : : }
438 : :
439 : : /*
440 : : * Get, initialize, write, and leave a lock of the appropriate type on
441 : : * the new root page. Since this is the first page in the tree, it's
442 : : * a leaf as well as the root.
443 : : */
444 : 697 : rootbuf = _bt_allocbuf(rel, heaprel);
445 : 697 : rootblkno = BufferGetBlockNumber(rootbuf);
446 : 697 : rootpage = BufferGetPage(rootbuf);
447 : 697 : rootopaque = BTPageGetOpaque(rootpage);
448 : 697 : rootopaque->btpo_prev = rootopaque->btpo_next = P_NONE;
449 : 697 : rootopaque->btpo_flags = (BTP_LEAF | BTP_ROOT);
450 : 697 : rootopaque->btpo_level = 0;
451 : 697 : rootopaque->btpo_cycleid = 0;
452 : : /* Get raw page pointer for metapage */
453 : 697 : metapg = BufferGetPage(metabuf);
454 : :
455 : : /* NO ELOG(ERROR) till meta is updated */
456 : 697 : START_CRIT_SECTION();
457 : :
458 : : /* upgrade metapage if needed */
459 [ + - ]: 697 : if (metad->btm_version < BTREE_NOVAC_VERSION)
460 : 0 : _bt_upgrademetapage(metapg);
461 : :
462 : 697 : metad->btm_root = rootblkno;
463 : 697 : metad->btm_level = 0;
464 : 697 : metad->btm_fastroot = rootblkno;
465 : 697 : metad->btm_fastlevel = 0;
466 : 697 : metad->btm_last_cleanup_num_delpages = 0;
467 : 697 : metad->btm_last_cleanup_num_heap_tuples = -1.0;
468 : :
469 : 697 : MarkBufferDirty(rootbuf);
470 : 697 : MarkBufferDirty(metabuf);
471 : :
472 : : /* XLOG stuff */
473 [ + + + + : 697 : if (RelationNeedsWAL(rel))
+ + - + ]
474 : : {
475 : 618 : xl_btree_newroot xlrec;
476 : 618 : XLogRecPtr recptr;
477 : 618 : xl_btree_metadata md;
478 : :
479 : 618 : XLogBeginInsert();
480 : 618 : XLogRegisterBuffer(0, rootbuf, REGBUF_WILL_INIT);
481 : 618 : XLogRegisterBuffer(2, metabuf, REGBUF_WILL_INIT | REGBUF_STANDARD);
482 : :
483 [ + - ]: 618 : Assert(metad->btm_version >= BTREE_NOVAC_VERSION);
484 : 618 : md.version = metad->btm_version;
485 : 618 : md.root = rootblkno;
486 : 618 : md.level = 0;
487 : 618 : md.fastroot = rootblkno;
488 : 618 : md.fastlevel = 0;
489 : 618 : md.last_cleanup_num_delpages = 0;
490 : 618 : md.allequalimage = metad->btm_allequalimage;
491 : :
492 : 618 : XLogRegisterBufData(2, &md, sizeof(xl_btree_metadata));
493 : :
494 : 618 : xlrec.rootblk = rootblkno;
495 : 618 : xlrec.level = 0;
496 : :
497 : 618 : XLogRegisterData(&xlrec, SizeOfBtreeNewroot);
498 : :
499 : 618 : recptr = XLogInsert(RM_BTREE_ID, XLOG_BTREE_NEWROOT);
500 : :
501 : 618 : PageSetLSN(rootpage, recptr);
502 : 618 : PageSetLSN(metapg, recptr);
503 : 618 : }
504 : :
505 [ + - ]: 697 : END_CRIT_SECTION();
506 : :
507 : : /*
508 : : * swap root write lock for read lock. There is no danger of anyone
509 : : * else accessing the new root page while it's unlocked, since no one
510 : : * else knows where it is yet.
511 : : */
512 : 697 : _bt_unlockbuf(rel, rootbuf);
513 : 697 : _bt_lockbuf(rel, rootbuf, BT_READ);
514 : :
515 : : /* okay, metadata is correct, release lock on it without caching */
516 : 697 : _bt_relbuf(rel, metabuf);
517 [ + + ]: 28242 : }
518 : : else
519 : : {
520 : 105 : rootblkno = metad->btm_fastroot;
521 [ + - ]: 105 : Assert(rootblkno != P_NONE);
522 : 105 : rootlevel = metad->btm_fastlevel;
523 : :
524 : : /*
525 : : * Cache the metapage data for next time
526 : : */
527 : 105 : rel->rd_amcache = MemoryContextAlloc(rel->rd_indexcxt,
528 : : sizeof(BTMetaPageData));
529 : 105 : memcpy(rel->rd_amcache, metad, sizeof(BTMetaPageData));
530 : :
531 : : /*
532 : : * We are done with the metapage; arrange to release it via first
533 : : * _bt_relandgetbuf call
534 : : */
535 : 105 : rootbuf = metabuf;
536 : :
537 : 105 : for (;;)
538 : : {
539 : 105 : rootbuf = _bt_relandgetbuf(rel, rootbuf, rootblkno, BT_READ);
540 : 105 : rootpage = BufferGetPage(rootbuf);
541 : 105 : rootopaque = BTPageGetOpaque(rootpage);
542 : :
543 [ - + ]: 105 : if (!P_IGNORE(rootopaque))
544 : 105 : break;
545 : :
546 : : /* it's dead, Jim. step right one page */
547 [ # # ]: 0 : if (P_RIGHTMOST(rootopaque))
548 [ # # # # ]: 0 : elog(ERROR, "no live root page found in index \"%s\"",
549 : : RelationGetRelationName(rel));
550 : 0 : rootblkno = rootopaque->btpo_next;
551 : : }
552 : :
553 [ + - ]: 105 : if (rootopaque->btpo_level != rootlevel)
554 [ # # # # ]: 0 : elog(ERROR, "root page %u of index \"%s\" has level %u, expected %u",
555 : : rootblkno, RelationGetRelationName(rel),
556 : : rootopaque->btpo_level, rootlevel);
557 : : }
558 : :
559 : : /*
560 : : * By here, we have a pin and read lock on the root page, and no lock set
561 : : * on the metadata page. Return the root page's buffer.
562 : : */
563 : 802 : return rootbuf;
564 : 1845721 : }
565 : :
566 : : /*
567 : : * _bt_gettrueroot() -- Get the true root page of the btree.
568 : : *
569 : : * This is the same as the BT_READ case of _bt_getroot(), except
570 : : * we follow the true-root link not the fast-root link.
571 : : *
572 : : * By the time we acquire lock on the root page, it might have been split and
573 : : * not be the true root anymore. This is okay for the present uses of this
574 : : * routine; we only really need to be able to move up at least one tree level
575 : : * from whatever non-root page we were at. If we ever do need to lock the
576 : : * one true root page, we could loop here, re-reading the metapage on each
577 : : * failure. (Note that it wouldn't do to hold the lock on the metapage while
578 : : * moving to the root --- that'd deadlock against any concurrent root split.)
579 : : */
580 : : Buffer
581 : 3 : _bt_gettrueroot(Relation rel)
582 : : {
583 : 3 : Buffer metabuf;
584 : 3 : Page metapg;
585 : 3 : BTPageOpaque metaopaque;
586 : 3 : Buffer rootbuf;
587 : 3 : Page rootpage;
588 : 3 : BTPageOpaque rootopaque;
589 : 3 : BlockNumber rootblkno;
590 : 3 : uint32 rootlevel;
591 : 3 : BTMetaPageData *metad;
592 : :
593 : : /*
594 : : * We don't try to use cached metapage data here, since (a) this path is
595 : : * not performance-critical, and (b) if we are here it suggests our cache
596 : : * is out-of-date anyway. In light of point (b), it's probably safest to
597 : : * actively flush any cached metapage info.
598 : : */
599 [ - + ]: 3 : if (rel->rd_amcache)
600 : 3 : pfree(rel->rd_amcache);
601 : 3 : rel->rd_amcache = NULL;
602 : :
603 : 3 : metabuf = _bt_getbuf(rel, BTREE_METAPAGE, BT_READ);
604 : 3 : metapg = BufferGetPage(metabuf);
605 : 3 : metaopaque = BTPageGetOpaque(metapg);
606 : 3 : metad = BTPageGetMeta(metapg);
607 : :
608 [ + - ]: 3 : if (!P_ISMETA(metaopaque) ||
609 : 3 : metad->btm_magic != BTREE_MAGIC)
610 [ # # # # ]: 0 : ereport(ERROR,
611 : : (errcode(ERRCODE_INDEX_CORRUPTED),
612 : : errmsg("index \"%s\" is not a btree",
613 : : RelationGetRelationName(rel))));
614 : :
615 [ + - ]: 3 : if (metad->btm_version < BTREE_MIN_VERSION ||
616 : 3 : metad->btm_version > BTREE_VERSION)
617 [ # # # # ]: 0 : ereport(ERROR,
618 : : (errcode(ERRCODE_INDEX_CORRUPTED),
619 : : errmsg("version mismatch in index \"%s\": file version %d, "
620 : : "current version %d, minimal supported version %d",
621 : : RelationGetRelationName(rel),
622 : : metad->btm_version, BTREE_VERSION, BTREE_MIN_VERSION)));
623 : :
624 : : /* if no root page initialized yet, fail */
625 [ + - ]: 3 : if (metad->btm_root == P_NONE)
626 : : {
627 : 0 : _bt_relbuf(rel, metabuf);
628 : 0 : return InvalidBuffer;
629 : : }
630 : :
631 : 3 : rootblkno = metad->btm_root;
632 : 3 : rootlevel = metad->btm_level;
633 : :
634 : : /*
635 : : * We are done with the metapage; arrange to release it via first
636 : : * _bt_relandgetbuf call
637 : : */
638 : 3 : rootbuf = metabuf;
639 : :
640 : 3 : for (;;)
641 : : {
642 : 3 : rootbuf = _bt_relandgetbuf(rel, rootbuf, rootblkno, BT_READ);
643 : 3 : rootpage = BufferGetPage(rootbuf);
644 : 3 : rootopaque = BTPageGetOpaque(rootpage);
645 : :
646 [ - + ]: 3 : if (!P_IGNORE(rootopaque))
647 : 3 : break;
648 : :
649 : : /* it's dead, Jim. step right one page */
650 [ # # ]: 0 : if (P_RIGHTMOST(rootopaque))
651 [ # # # # ]: 0 : elog(ERROR, "no live root page found in index \"%s\"",
652 : : RelationGetRelationName(rel));
653 : 0 : rootblkno = rootopaque->btpo_next;
654 : : }
655 : :
656 [ + - ]: 3 : if (rootopaque->btpo_level != rootlevel)
657 [ # # # # ]: 0 : elog(ERROR, "root page %u of index \"%s\" has level %u, expected %u",
658 : : rootblkno, RelationGetRelationName(rel),
659 : : rootopaque->btpo_level, rootlevel);
660 : :
661 : 3 : return rootbuf;
662 : 3 : }
663 : :
664 : : /*
665 : : * _bt_getrootheight() -- Get the height of the btree search tree.
666 : : *
667 : : * We return the level (counting from zero) of the current fast root.
668 : : * This represents the number of tree levels we'd have to descend through
669 : : * to start any btree index search.
670 : : *
671 : : * This is used by the planner for cost-estimation purposes. Since it's
672 : : * only an estimate, slightly-stale data is fine, hence we don't worry
673 : : * about updating previously cached data.
674 : : */
675 : : int
676 : 644878 : _bt_getrootheight(Relation rel)
677 : : {
678 : 644878 : BTMetaPageData *metad;
679 : :
680 [ + + ]: 644878 : if (rel->rd_amcache == NULL)
681 : : {
682 : 6820 : Buffer metabuf;
683 : :
684 : 6820 : metabuf = _bt_getbuf(rel, BTREE_METAPAGE, BT_READ);
685 : 6820 : metad = _bt_getmeta(rel, metabuf);
686 : :
687 : : /*
688 : : * If there's no root page yet, _bt_getroot() doesn't expect a cache
689 : : * to be made, so just stop here and report the index height is zero.
690 : : * (XXX perhaps _bt_getroot() should be changed to allow this case.)
691 : : */
692 [ + + ]: 6820 : if (metad->btm_root == P_NONE)
693 : : {
694 : 5053 : _bt_relbuf(rel, metabuf);
695 : 5053 : return 0;
696 : : }
697 : :
698 : : /*
699 : : * Cache the metapage data for next time
700 : : */
701 : 1767 : rel->rd_amcache = MemoryContextAlloc(rel->rd_indexcxt,
702 : : sizeof(BTMetaPageData));
703 : 1767 : memcpy(rel->rd_amcache, metad, sizeof(BTMetaPageData));
704 : 1767 : _bt_relbuf(rel, metabuf);
705 [ + + ]: 6820 : }
706 : :
707 : : /* Get cached page */
708 : 639825 : metad = (BTMetaPageData *) rel->rd_amcache;
709 : : /* We shouldn't have cached it if any of these fail */
710 [ + - ]: 639825 : Assert(metad->btm_magic == BTREE_MAGIC);
711 [ + - ]: 639825 : Assert(metad->btm_version >= BTREE_MIN_VERSION);
712 [ + - ]: 639825 : Assert(metad->btm_version <= BTREE_VERSION);
713 [ + + + - ]: 639825 : Assert(!metad->btm_allequalimage ||
714 : : metad->btm_version > BTREE_NOVAC_VERSION);
715 [ + - ]: 639825 : Assert(metad->btm_fastroot != P_NONE);
716 : :
717 : 639825 : return metad->btm_fastlevel;
718 : 644878 : }
719 : :
720 : : /*
721 : : * _bt_metaversion() -- Get version/status info from metapage.
722 : : *
723 : : * Sets caller's *heapkeyspace and *allequalimage arguments using data
724 : : * from the B-Tree metapage (could be locally-cached version). This
725 : : * information needs to be stashed in insertion scankey, so we provide a
726 : : * single function that fetches both at once.
727 : : *
728 : : * This is used to determine the rules that must be used to descend a
729 : : * btree. Version 4 indexes treat heap TID as a tiebreaker attribute.
730 : : * pg_upgrade'd version 3 indexes need extra steps to preserve reasonable
731 : : * performance when inserting a new BTScanInsert-wise duplicate tuple
732 : : * among many leaf pages already full of such duplicates.
733 : : *
734 : : * Also sets allequalimage field, which indicates whether or not it is
735 : : * safe to apply deduplication. We rely on the assumption that
736 : : * btm_allequalimage will be zero'ed on heapkeyspace indexes that were
737 : : * pg_upgrade'd from Postgres 12.
738 : : */
739 : : void
740 : 1839280 : _bt_metaversion(Relation rel, bool *heapkeyspace, bool *allequalimage)
741 : : {
742 : 1839280 : BTMetaPageData *metad;
743 : :
744 [ + + ]: 1839280 : if (rel->rd_amcache == NULL)
745 : : {
746 : 53286 : Buffer metabuf;
747 : :
748 : 53286 : metabuf = _bt_getbuf(rel, BTREE_METAPAGE, BT_READ);
749 : 53286 : metad = _bt_getmeta(rel, metabuf);
750 : :
751 : : /*
752 : : * If there's no root page yet, _bt_getroot() doesn't expect a cache
753 : : * to be made, so just stop here. (XXX perhaps _bt_getroot() should
754 : : * be changed to allow this case.)
755 : : */
756 [ + + ]: 53286 : if (metad->btm_root == P_NONE)
757 : : {
758 : 27903 : *heapkeyspace = metad->btm_version > BTREE_NOVAC_VERSION;
759 : 27903 : *allequalimage = metad->btm_allequalimage;
760 : :
761 : 27903 : _bt_relbuf(rel, metabuf);
762 : 27903 : return;
763 : : }
764 : :
765 : : /*
766 : : * Cache the metapage data for next time
767 : : *
768 : : * An on-the-fly version upgrade performed by _bt_upgrademetapage()
769 : : * can change the nbtree version for an index without invalidating any
770 : : * local cache. This is okay because it can only happen when moving
771 : : * from version 2 to version 3, both of which are !heapkeyspace
772 : : * versions.
773 : : */
774 : 25383 : rel->rd_amcache = MemoryContextAlloc(rel->rd_indexcxt,
775 : : sizeof(BTMetaPageData));
776 : 25383 : memcpy(rel->rd_amcache, metad, sizeof(BTMetaPageData));
777 : 25383 : _bt_relbuf(rel, metabuf);
778 [ + + ]: 53286 : }
779 : :
780 : : /* Get cached page */
781 : 1811377 : metad = (BTMetaPageData *) rel->rd_amcache;
782 : : /* We shouldn't have cached it if any of these fail */
783 [ + - ]: 1811377 : Assert(metad->btm_magic == BTREE_MAGIC);
784 [ + - ]: 1811377 : Assert(metad->btm_version >= BTREE_MIN_VERSION);
785 [ + - ]: 1811377 : Assert(metad->btm_version <= BTREE_VERSION);
786 [ + + + - ]: 1811377 : Assert(!metad->btm_allequalimage ||
787 : : metad->btm_version > BTREE_NOVAC_VERSION);
788 [ + - ]: 1811377 : Assert(metad->btm_fastroot != P_NONE);
789 : :
790 : 1811377 : *heapkeyspace = metad->btm_version > BTREE_NOVAC_VERSION;
791 : 1811377 : *allequalimage = metad->btm_allequalimage;
792 [ - + ]: 1839280 : }
793 : :
794 : : /*
795 : : * _bt_checkpage() -- Verify that a freshly-read page looks sane.
796 : : */
797 : : void
798 : 3508720 : _bt_checkpage(Relation rel, Buffer buf)
799 : : {
800 : 3508720 : Page page = BufferGetPage(buf);
801 : :
802 : : /*
803 : : * ReadBuffer verifies that every newly-read page passes
804 : : * PageHeaderIsValid, which means it either contains a reasonably sane
805 : : * page header or is all-zero. We have to defend against the all-zero
806 : : * case, however.
807 : : */
808 [ + - ]: 3508720 : if (PageIsNew(page))
809 [ # # # # ]: 0 : ereport(ERROR,
810 : : (errcode(ERRCODE_INDEX_CORRUPTED),
811 : : errmsg("index \"%s\" contains unexpected zero page at block %u",
812 : : RelationGetRelationName(rel),
813 : : BufferGetBlockNumber(buf)),
814 : : errhint("Please REINDEX it.")));
815 : :
816 : : /*
817 : : * Additionally check that the special area looks sane.
818 : : */
819 [ + - ]: 3508720 : if (PageGetSpecialSize(page) != MAXALIGN(sizeof(BTPageOpaqueData)))
820 [ # # # # ]: 0 : ereport(ERROR,
821 : : (errcode(ERRCODE_INDEX_CORRUPTED),
822 : : errmsg("index \"%s\" contains corrupted page at block %u",
823 : : RelationGetRelationName(rel),
824 : : BufferGetBlockNumber(buf)),
825 : : errhint("Please REINDEX it.")));
826 : 3508720 : }
827 : :
828 : : /*
829 : : * _bt_getbuf() -- Get an existing block in a buffer, for read or write.
830 : : *
831 : : * The general rule in nbtree is that it's never okay to access a
832 : : * page without holding both a buffer pin and a buffer lock on
833 : : * the page's buffer.
834 : : *
835 : : * When this routine returns, the appropriate lock is set on the
836 : : * requested buffer and its reference count has been incremented
837 : : * (ie, the buffer is "locked and pinned"). Also, we apply
838 : : * _bt_checkpage to sanity-check the page, and perform Valgrind
839 : : * client requests that help Valgrind detect unsafe page accesses.
840 : : *
841 : : * Note: raw LockBuffer() calls are disallowed in nbtree; all
842 : : * buffer lock requests need to go through wrapper functions such
843 : : * as _bt_lockbuf().
844 : : */
845 : : Buffer
846 : 1921354 : _bt_getbuf(Relation rel, BlockNumber blkno, int access)
847 : : {
848 : 1921354 : Buffer buf;
849 : :
850 [ + - ]: 1921354 : Assert(BlockNumberIsValid(blkno));
851 : :
852 : : /* Read an existing block of the relation */
853 : 1921354 : buf = ReadBuffer(rel, blkno);
854 : 1921354 : _bt_lockbuf(rel, buf, access);
855 : 1921354 : _bt_checkpage(rel, buf);
856 : :
857 : 3842708 : return buf;
858 : 1921354 : }
859 : :
860 : : /*
861 : : * _bt_allocbuf() -- Allocate a new block/page.
862 : : *
863 : : * Returns a write-locked buffer containing an unallocated nbtree page.
864 : : *
865 : : * Callers are required to pass a valid heaprel. We need heaprel so that we
866 : : * can handle generating a snapshotConflictHorizon that makes reusing a page
867 : : * from the FSM safe for queries that may be running on standbys.
868 : : */
869 : : Buffer
870 : 3077 : _bt_allocbuf(Relation rel, Relation heaprel)
871 : : {
872 : 3077 : Buffer buf;
873 : 3077 : BlockNumber blkno;
874 : 3077 : Page page;
875 : :
876 [ + - ]: 3077 : Assert(heaprel != NULL);
877 : :
878 : : /*
879 : : * First see if the FSM knows of any free pages.
880 : : *
881 : : * We can't trust the FSM's report unreservedly; we have to check that the
882 : : * page is still free. (For example, an already-free page could have been
883 : : * re-used between the time the last VACUUM scanned it and the time the
884 : : * VACUUM made its FSM updates.)
885 : : *
886 : : * In fact, it's worse than that: we can't even assume that it's safe to
887 : : * take a lock on the reported page. If somebody else has a lock on it,
888 : : * or even worse our own caller does, we could deadlock. (The own-caller
889 : : * scenario is actually not improbable. Consider an index on a serial or
890 : : * timestamp column. Nearly all splits will be at the rightmost page, so
891 : : * it's entirely likely that _bt_split will call us while holding a lock
892 : : * on the page most recently acquired from FSM. A VACUUM running
893 : : * concurrently with the previous split could well have placed that page
894 : : * back in FSM.)
895 : : *
896 : : * To get around that, we ask for only a conditional lock on the reported
897 : : * page. If we fail, then someone else is using the page, and we may
898 : : * reasonably assume it's not free. (If we happen to be wrong, the worst
899 : : * consequence is the page will be lost to use till the next VACUUM, which
900 : : * is no big problem.)
901 : : */
902 : 3077 : for (;;)
903 : : {
904 : 3077 : blkno = GetFreeIndexPage(rel);
905 [ + + ]: 3077 : if (blkno == InvalidBlockNumber)
906 : 3066 : break;
907 : 11 : buf = ReadBuffer(rel, blkno);
908 [ + - ]: 11 : if (_bt_conditionallockbuf(rel, buf))
909 : : {
910 : 11 : page = BufferGetPage(buf);
911 : :
912 : : /*
913 : : * It's possible to find an all-zeroes page in an index. For
914 : : * example, a backend might successfully extend the relation one
915 : : * page and then crash before it is able to make a WAL entry for
916 : : * adding the page. If we find a zeroed page then reclaim it
917 : : * immediately.
918 : : */
919 [ - + ]: 11 : if (PageIsNew(page))
920 : : {
921 : : /* Okay to use page. Initialize and return it. */
922 : 0 : _bt_pageinit(page, BufferGetPageSize(buf));
923 : 0 : return buf;
924 : : }
925 : :
926 [ - + ]: 11 : if (BTPageIsRecyclable(page, heaprel))
927 : : {
928 : : /*
929 : : * If we are generating WAL for Hot Standby then create a WAL
930 : : * record that will allow us to conflict with queries running
931 : : * on standby, in case they have snapshots older than safexid
932 : : * value
933 : : */
934 [ + - + - : 11 : if (RelationNeedsWAL(rel) && XLogStandbyInfoActive())
+ - # # ]
935 : : {
936 : 0 : xl_btree_reuse_page xlrec_reuse;
937 : :
938 : : /*
939 : : * Note that we don't register the buffer with the record,
940 : : * because this operation doesn't modify the page (that
941 : : * already happened, back when VACUUM deleted the page).
942 : : * This record only exists to provide a conflict point for
943 : : * Hot Standby. See record REDO routine comments.
944 : : */
945 : 0 : xlrec_reuse.locator = rel->rd_locator;
946 : 0 : xlrec_reuse.block = blkno;
947 : 0 : xlrec_reuse.snapshotConflictHorizon = BTPageGetDeleteXid(page);
948 : 0 : xlrec_reuse.isCatalogRel =
949 [ # # # # : 0 : RelationIsAccessibleInLogicalDecoding(heaprel);
# # # # #
# # # # #
# # # # ]
950 : :
951 : 0 : XLogBeginInsert();
952 : 0 : XLogRegisterData(&xlrec_reuse, SizeOfBtreeReusePage);
953 : :
954 : 0 : XLogInsert(RM_BTREE_ID, XLOG_BTREE_REUSE_PAGE);
955 : 0 : }
956 : :
957 : : /* Okay to use page. Re-initialize and return it. */
958 : 11 : _bt_pageinit(page, BufferGetPageSize(buf));
959 : 11 : return buf;
960 : : }
961 [ # # # # ]: 0 : elog(DEBUG2, "FSM returned nonrecyclable page");
962 : 0 : _bt_relbuf(rel, buf);
963 : 0 : }
964 : : else
965 : : {
966 [ # # # # ]: 0 : elog(DEBUG2, "FSM returned nonlockable page");
967 : : /* couldn't get lock, so just drop pin */
968 : 0 : ReleaseBuffer(buf);
969 : : }
970 : : }
971 : :
972 : : /*
973 : : * Extend the relation by one page. Need to use RBM_ZERO_AND_LOCK or we
974 : : * risk a race condition against btvacuumscan --- see comments therein.
975 : : * This forces us to repeat the valgrind request that _bt_lockbuf()
976 : : * otherwise would make, as we can't use _bt_lockbuf() without introducing
977 : : * a race.
978 : : */
979 : 3066 : buf = ExtendBufferedRel(BMR_REL(rel), MAIN_FORKNUM, NULL, EB_LOCK_FIRST);
980 [ + + ]: 3066 : if (!RelationUsesLocalBuffers(rel))
981 : 2966 : VALGRIND_MAKE_MEM_DEFINED(BufferGetPage(buf), BLCKSZ);
982 : :
983 : : /* Initialize the new page before returning it */
984 : 3066 : page = BufferGetPage(buf);
985 [ + - ]: 3066 : Assert(PageIsNew(page));
986 : 3066 : _bt_pageinit(page, BufferGetPageSize(buf));
987 : :
988 : 3066 : return buf;
989 : 3077 : }
990 : :
991 : : /*
992 : : * _bt_relandgetbuf() -- release a locked buffer and get another one.
993 : : *
994 : : * This is equivalent to _bt_relbuf followed by _bt_getbuf. Also, if obuf is
995 : : * InvalidBuffer then it reduces to just _bt_getbuf; allowing this case
996 : : * simplifies some callers.
997 : : *
998 : : * The original motivation for using this was to avoid two entries to the
999 : : * bufmgr when one would do. However, now it's mainly just a notational
1000 : : * convenience. The only case where it saves work over _bt_relbuf/_bt_getbuf
1001 : : * is when the target page is the same one already in the buffer.
1002 : : */
1003 : : Buffer
1004 : 1586453 : _bt_relandgetbuf(Relation rel, Buffer obuf, BlockNumber blkno, int access)
1005 : : {
1006 : 1586453 : Buffer buf;
1007 : :
1008 [ + - ]: 1586453 : Assert(BlockNumberIsValid(blkno));
1009 [ + + ]: 1586453 : if (BufferIsValid(obuf))
1010 : 1583819 : _bt_unlockbuf(rel, obuf);
1011 : 1586453 : buf = ReleaseAndReadBuffer(obuf, rel, blkno);
1012 : 1586453 : _bt_lockbuf(rel, buf, access);
1013 : :
1014 : 1586453 : _bt_checkpage(rel, buf);
1015 : 3172906 : return buf;
1016 : 1586453 : }
1017 : :
1018 : : /*
1019 : : * _bt_relbuf() -- release a locked buffer.
1020 : : *
1021 : : * Lock and pin (refcount) are both dropped.
1022 : : */
1023 : : void
1024 : 1605453 : _bt_relbuf(Relation rel, Buffer buf)
1025 : : {
1026 : 1605453 : _bt_unlockbuf(rel, buf);
1027 : 1605453 : ReleaseBuffer(buf);
1028 : 1605453 : }
1029 : :
1030 : : /*
1031 : : * _bt_lockbuf() -- lock a pinned buffer.
1032 : : *
1033 : : * Lock is acquired without acquiring another pin. This is like a raw
1034 : : * LockBuffer() call, but performs extra steps needed by Valgrind.
1035 : : *
1036 : : * Note: Caller may need to call _bt_checkpage() with buf when pin on buf
1037 : : * wasn't originally acquired in _bt_getbuf() or _bt_relandgetbuf().
1038 : : */
1039 : : void
1040 : 3574648 : _bt_lockbuf(Relation rel, Buffer buf, int access)
1041 : : {
1042 : : /* LockBuffer() asserts that pin is held by this backend */
1043 : 3574648 : LockBuffer(buf, access);
1044 : :
1045 : : /*
1046 : : * It doesn't matter that _bt_unlockbuf() won't get called in the event of
1047 : : * an nbtree error (e.g. a unique violation error). That won't cause
1048 : : * Valgrind false positives.
1049 : : *
1050 : : * The nbtree client requests are superimposed on top of the bufmgr.c
1051 : : * buffer pin client requests. In the event of an nbtree error the buffer
1052 : : * will certainly get marked as defined when the backend once again
1053 : : * acquires its first pin on the buffer. (Of course, if the backend never
1054 : : * touches the buffer again then it doesn't matter that it remains
1055 : : * non-accessible to Valgrind.)
1056 : : *
1057 : : * Note: When an IndexTuple C pointer gets computed using an ItemId read
1058 : : * from a page while a lock was held, the C pointer becomes unsafe to
1059 : : * dereference forever as soon as the lock is released. Valgrind can only
1060 : : * detect cases where the pointer gets dereferenced with no _current_
1061 : : * lock/pin held, though.
1062 : : */
1063 [ + + ]: 3574648 : if (!RelationUsesLocalBuffers(rel))
1064 : 3548080 : VALGRIND_MAKE_MEM_DEFINED(BufferGetPage(buf), BLCKSZ);
1065 : 3574648 : }
1066 : :
1067 : : /*
1068 : : * _bt_unlockbuf() -- unlock a pinned buffer.
1069 : : */
1070 : : void
1071 : 3577763 : _bt_unlockbuf(Relation rel, Buffer buf)
1072 : : {
1073 : : /*
1074 : : * Buffer is pinned and locked, which means that it is expected to be
1075 : : * defined and addressable. Check that proactively.
1076 : : */
1077 : 3577763 : VALGRIND_CHECK_MEM_IS_DEFINED(BufferGetPage(buf), BLCKSZ);
1078 : :
1079 : : /* LockBuffer() asserts that pin is held by this backend */
1080 : 3577763 : LockBuffer(buf, BUFFER_LOCK_UNLOCK);
1081 : :
1082 [ + + ]: 3577763 : if (!RelationUsesLocalBuffers(rel))
1083 : 3551095 : VALGRIND_MAKE_MEM_NOACCESS(BufferGetPage(buf), BLCKSZ);
1084 : 3577763 : }
1085 : :
1086 : : /*
1087 : : * _bt_conditionallockbuf() -- conditionally BT_WRITE lock pinned
1088 : : * buffer.
1089 : : *
1090 : : * Note: Caller may need to call _bt_checkpage() with buf when pin on buf
1091 : : * wasn't originally acquired in _bt_getbuf() or _bt_relandgetbuf().
1092 : : */
1093 : : bool
1094 : 49 : _bt_conditionallockbuf(Relation rel, Buffer buf)
1095 : : {
1096 : : /* ConditionalLockBuffer() asserts that pin is held by this backend */
1097 [ - + ]: 49 : if (!ConditionalLockBuffer(buf))
1098 : 0 : return false;
1099 : :
1100 [ - + ]: 49 : if (!RelationUsesLocalBuffers(rel))
1101 : 49 : VALGRIND_MAKE_MEM_DEFINED(BufferGetPage(buf), BLCKSZ);
1102 : :
1103 : 49 : return true;
1104 : 49 : }
1105 : :
1106 : : /*
1107 : : * _bt_upgradelockbufcleanup() -- upgrade lock to a full cleanup lock.
1108 : : */
1109 : : void
1110 : 733 : _bt_upgradelockbufcleanup(Relation rel, Buffer buf)
1111 : : {
1112 : : /*
1113 : : * Buffer is pinned and locked, which means that it is expected to be
1114 : : * defined and addressable. Check that proactively.
1115 : : */
1116 : 733 : VALGRIND_CHECK_MEM_IS_DEFINED(BufferGetPage(buf), BLCKSZ);
1117 : :
1118 : : /* LockBuffer() asserts that pin is held by this backend */
1119 : 733 : LockBuffer(buf, BUFFER_LOCK_UNLOCK);
1120 : 733 : LockBufferForCleanup(buf);
1121 : 733 : }
1122 : :
1123 : : /*
1124 : : * _bt_pageinit() -- Initialize a new page.
1125 : : *
1126 : : * On return, the page header is initialized; data space is empty;
1127 : : * special space is zeroed out.
1128 : : */
1129 : : void
1130 : 13079 : _bt_pageinit(Page page, Size size)
1131 : : {
1132 : 13079 : PageInit(page, size, sizeof(BTPageOpaqueData));
1133 : 13079 : }
1134 : :
1135 : : /*
1136 : : * Delete item(s) from a btree leaf page during VACUUM.
1137 : : *
1138 : : * This routine assumes that the caller already has a full cleanup lock on
1139 : : * the buffer. Also, the given deletable and updatable arrays *must* be
1140 : : * sorted in ascending order.
1141 : : *
1142 : : * Routine deals with deleting TIDs when some (but not all) of the heap TIDs
1143 : : * in an existing posting list item are to be removed. This works by
1144 : : * updating/overwriting an existing item with caller's new version of the item
1145 : : * (a version that lacks the TIDs that are to be deleted).
1146 : : *
1147 : : * We record VACUUMs and b-tree deletes differently in WAL. Deletes must
1148 : : * generate their own snapshotConflictHorizon directly from the tableam,
1149 : : * whereas VACUUMs rely on the initial VACUUM table scan performing
1150 : : * WAL-logging that takes care of the issue for the table's indexes
1151 : : * indirectly. Also, we remove the VACUUM cycle ID from pages, which b-tree
1152 : : * deletes don't do.
1153 : : */
1154 : : void
1155 : 515 : _bt_delitems_vacuum(Relation rel, Buffer buf,
1156 : : OffsetNumber *deletable, int ndeletable,
1157 : : BTVacuumPosting *updatable, int nupdatable)
1158 : : {
1159 : 515 : Page page = BufferGetPage(buf);
1160 : 515 : BTPageOpaque opaque;
1161 [ - + + + : 1030 : bool needswal = RelationNeedsWAL(rel);
- + ]
1162 : 515 : char *updatedbuf = NULL;
1163 : 515 : Size updatedbuflen = 0;
1164 : 515 : OffsetNumber updatedoffsets[MaxIndexTuplesPerPage];
1165 : :
1166 : : /* Shouldn't be called unless there's something to do */
1167 [ + + + - ]: 515 : Assert(ndeletable > 0 || nupdatable > 0);
1168 : :
1169 : : /* Generate new version of posting lists without deleted TIDs */
1170 [ + + ]: 515 : if (nupdatable > 0)
1171 : 102 : updatedbuf = _bt_delitems_update(updatable, nupdatable,
1172 : 51 : updatedoffsets, &updatedbuflen,
1173 : 51 : needswal);
1174 : :
1175 : : /* No ereport(ERROR) until changes are logged */
1176 : 515 : START_CRIT_SECTION();
1177 : :
1178 : : /*
1179 : : * Handle posting tuple updates.
1180 : : *
1181 : : * Deliberately do this before handling simple deletes. If we did it the
1182 : : * other way around (i.e. WAL record order -- simple deletes before
1183 : : * updates) then we'd have to make compensating changes to the 'updatable'
1184 : : * array of offset numbers.
1185 : : *
1186 : : * PageIndexTupleOverwrite() won't unset each item's LP_DEAD bit when it
1187 : : * happens to already be set. It's important that we not interfere with
1188 : : * any future simple index tuple deletion operations.
1189 : : */
1190 [ + + ]: 1648 : for (int i = 0; i < nupdatable; i++)
1191 : : {
1192 : 1133 : OffsetNumber updatedoffset = updatedoffsets[i];
1193 : 1133 : IndexTuple itup;
1194 : 1133 : Size itemsz;
1195 : :
1196 : 1133 : itup = updatable[i]->itup;
1197 : 1133 : itemsz = MAXALIGN(IndexTupleSize(itup));
1198 [ + - ]: 1133 : if (!PageIndexTupleOverwrite(page, updatedoffset, itup, itemsz))
1199 [ # # # # ]: 0 : elog(PANIC, "failed to update partially dead item in block %u of index \"%s\"",
1200 : : BufferGetBlockNumber(buf), RelationGetRelationName(rel));
1201 : 1133 : }
1202 : :
1203 : : /* Now handle simple deletes of entire tuples */
1204 [ + + ]: 515 : if (ndeletable > 0)
1205 : 509 : PageIndexMultiDelete(page, deletable, ndeletable);
1206 : :
1207 : : /*
1208 : : * We can clear the vacuum cycle ID since this page has certainly been
1209 : : * processed by the current vacuum scan.
1210 : : */
1211 : 515 : opaque = BTPageGetOpaque(page);
1212 : 515 : opaque->btpo_cycleid = 0;
1213 : :
1214 : : /*
1215 : : * Clear the BTP_HAS_GARBAGE page flag.
1216 : : *
1217 : : * This flag indicates the presence of LP_DEAD items on the page (though
1218 : : * not reliably). Note that we only rely on it with pg_upgrade'd
1219 : : * !heapkeyspace indexes. That's why clearing it here won't usually
1220 : : * interfere with simple index tuple deletion.
1221 : : */
1222 : 515 : opaque->btpo_flags &= ~BTP_HAS_GARBAGE;
1223 : :
1224 : 515 : MarkBufferDirty(buf);
1225 : :
1226 : : /* XLOG stuff */
1227 [ - + ]: 515 : if (needswal)
1228 : : {
1229 : 515 : XLogRecPtr recptr;
1230 : 515 : xl_btree_vacuum xlrec_vacuum;
1231 : :
1232 : 515 : xlrec_vacuum.ndeleted = ndeletable;
1233 : 515 : xlrec_vacuum.nupdated = nupdatable;
1234 : :
1235 : 515 : XLogBeginInsert();
1236 : 515 : XLogRegisterBuffer(0, buf, REGBUF_STANDARD);
1237 : 515 : XLogRegisterData(&xlrec_vacuum, SizeOfBtreeVacuum);
1238 : :
1239 [ + + ]: 515 : if (ndeletable > 0)
1240 : 1018 : XLogRegisterBufData(0, deletable,
1241 : 509 : ndeletable * sizeof(OffsetNumber));
1242 : :
1243 [ + + ]: 515 : if (nupdatable > 0)
1244 : : {
1245 : 102 : XLogRegisterBufData(0, updatedoffsets,
1246 : 51 : nupdatable * sizeof(OffsetNumber));
1247 : 51 : XLogRegisterBufData(0, updatedbuf, updatedbuflen);
1248 : 51 : }
1249 : :
1250 : 515 : recptr = XLogInsert(RM_BTREE_ID, XLOG_BTREE_VACUUM);
1251 : :
1252 : 515 : PageSetLSN(page, recptr);
1253 : 515 : }
1254 : :
1255 [ + - ]: 515 : END_CRIT_SECTION();
1256 : :
1257 : : /* can't leak memory here */
1258 [ + + ]: 515 : if (updatedbuf != NULL)
1259 : 51 : pfree(updatedbuf);
1260 : : /* free tuples allocated within _bt_delitems_update() */
1261 [ + + ]: 1648 : for (int i = 0; i < nupdatable; i++)
1262 : 1133 : pfree(updatable[i]->itup);
1263 : 515 : }
1264 : :
1265 : : /*
1266 : : * Delete item(s) from a btree leaf page during single-page cleanup.
1267 : : *
1268 : : * This routine assumes that the caller has pinned and write locked the
1269 : : * buffer. Also, the given deletable and updatable arrays *must* be sorted in
1270 : : * ascending order.
1271 : : *
1272 : : * Routine deals with deleting TIDs when some (but not all) of the heap TIDs
1273 : : * in an existing posting list item are to be removed. This works by
1274 : : * updating/overwriting an existing item with caller's new version of the item
1275 : : * (a version that lacks the TIDs that are to be deleted).
1276 : : *
1277 : : * This is nearly the same as _bt_delitems_vacuum as far as what it does to
1278 : : * the page, but it needs its own snapshotConflictHorizon and isCatalogRel
1279 : : * (from the tableam). This is used by the REDO routine to generate recovery
1280 : : * conflicts. The other difference is that only _bt_delitems_vacuum will
1281 : : * clear page's VACUUM cycle ID.
1282 : : */
1283 : : static void
1284 : 885 : _bt_delitems_delete(Relation rel, Buffer buf,
1285 : : TransactionId snapshotConflictHorizon, bool isCatalogRel,
1286 : : OffsetNumber *deletable, int ndeletable,
1287 : : BTVacuumPosting *updatable, int nupdatable)
1288 : : {
1289 : 885 : Page page = BufferGetPage(buf);
1290 : 885 : BTPageOpaque opaque;
1291 [ - + + + : 1770 : bool needswal = RelationNeedsWAL(rel);
+ + ]
1292 : 885 : char *updatedbuf = NULL;
1293 : 885 : Size updatedbuflen = 0;
1294 : 885 : OffsetNumber updatedoffsets[MaxIndexTuplesPerPage];
1295 : :
1296 : : /* Shouldn't be called unless there's something to do */
1297 [ + + + - ]: 885 : Assert(ndeletable > 0 || nupdatable > 0);
1298 : :
1299 : : /* Generate new versions of posting lists without deleted TIDs */
1300 [ + + ]: 885 : if (nupdatable > 0)
1301 : 152 : updatedbuf = _bt_delitems_update(updatable, nupdatable,
1302 : 76 : updatedoffsets, &updatedbuflen,
1303 : 76 : needswal);
1304 : :
1305 : : /* No ereport(ERROR) until changes are logged */
1306 : 885 : START_CRIT_SECTION();
1307 : :
1308 : : /* Handle updates and deletes just like _bt_delitems_vacuum */
1309 [ + + ]: 1157 : for (int i = 0; i < nupdatable; i++)
1310 : : {
1311 : 272 : OffsetNumber updatedoffset = updatedoffsets[i];
1312 : 272 : IndexTuple itup;
1313 : 272 : Size itemsz;
1314 : :
1315 : 272 : itup = updatable[i]->itup;
1316 : 272 : itemsz = MAXALIGN(IndexTupleSize(itup));
1317 [ + - ]: 272 : if (!PageIndexTupleOverwrite(page, updatedoffset, itup, itemsz))
1318 [ # # # # ]: 0 : elog(PANIC, "failed to update partially dead item in block %u of index \"%s\"",
1319 : : BufferGetBlockNumber(buf), RelationGetRelationName(rel));
1320 : 272 : }
1321 : :
1322 [ + + ]: 885 : if (ndeletable > 0)
1323 : 884 : PageIndexMultiDelete(page, deletable, ndeletable);
1324 : :
1325 : : /*
1326 : : * Unlike _bt_delitems_vacuum, we *must not* clear the vacuum cycle ID at
1327 : : * this point. The VACUUM command alone controls vacuum cycle IDs.
1328 : : */
1329 : 885 : opaque = BTPageGetOpaque(page);
1330 : :
1331 : : /*
1332 : : * Clear the BTP_HAS_GARBAGE page flag.
1333 : : *
1334 : : * This flag indicates the presence of LP_DEAD items on the page (though
1335 : : * not reliably). Note that we only rely on it with pg_upgrade'd
1336 : : * !heapkeyspace indexes.
1337 : : */
1338 : 885 : opaque->btpo_flags &= ~BTP_HAS_GARBAGE;
1339 : :
1340 : 885 : MarkBufferDirty(buf);
1341 : :
1342 : : /* XLOG stuff */
1343 [ + + ]: 885 : if (needswal)
1344 : : {
1345 : 861 : XLogRecPtr recptr;
1346 : 861 : xl_btree_delete xlrec_delete;
1347 : :
1348 : 861 : xlrec_delete.snapshotConflictHorizon = snapshotConflictHorizon;
1349 : 861 : xlrec_delete.ndeleted = ndeletable;
1350 : 861 : xlrec_delete.nupdated = nupdatable;
1351 : 861 : xlrec_delete.isCatalogRel = isCatalogRel;
1352 : :
1353 : 861 : XLogBeginInsert();
1354 : 861 : XLogRegisterBuffer(0, buf, REGBUF_STANDARD);
1355 : 861 : XLogRegisterData(&xlrec_delete, SizeOfBtreeDelete);
1356 : :
1357 [ + + ]: 861 : if (ndeletable > 0)
1358 : 1720 : XLogRegisterBufData(0, deletable,
1359 : 860 : ndeletable * sizeof(OffsetNumber));
1360 : :
1361 [ + + ]: 861 : if (nupdatable > 0)
1362 : : {
1363 : 152 : XLogRegisterBufData(0, updatedoffsets,
1364 : 76 : nupdatable * sizeof(OffsetNumber));
1365 : 76 : XLogRegisterBufData(0, updatedbuf, updatedbuflen);
1366 : 76 : }
1367 : :
1368 : 861 : recptr = XLogInsert(RM_BTREE_ID, XLOG_BTREE_DELETE);
1369 : :
1370 : 861 : PageSetLSN(page, recptr);
1371 : 861 : }
1372 : :
1373 [ + - ]: 885 : END_CRIT_SECTION();
1374 : :
1375 : : /* can't leak memory here */
1376 [ + + ]: 885 : if (updatedbuf != NULL)
1377 : 76 : pfree(updatedbuf);
1378 : : /* free tuples allocated within _bt_delitems_update() */
1379 [ + + ]: 1157 : for (int i = 0; i < nupdatable; i++)
1380 : 272 : pfree(updatable[i]->itup);
1381 : 885 : }
1382 : :
1383 : : /*
1384 : : * Set up state needed to delete TIDs from posting list tuples via "updating"
1385 : : * the tuple. Performs steps common to both _bt_delitems_vacuum and
1386 : : * _bt_delitems_delete. These steps must take place before each function's
1387 : : * critical section begins.
1388 : : *
1389 : : * updatable and nupdatable are inputs, though note that we will use
1390 : : * _bt_update_posting() to replace the original itup with a pointer to a final
1391 : : * version in palloc()'d memory. Caller should free the tuples when its done.
1392 : : *
1393 : : * The first nupdatable entries from updatedoffsets are set to the page offset
1394 : : * number for posting list tuples that caller updates. This is mostly useful
1395 : : * because caller may need to WAL-log the page offsets (though we always do
1396 : : * this for caller out of convenience).
1397 : : *
1398 : : * Returns buffer consisting of an array of xl_btree_update structs that
1399 : : * describe the steps we perform here for caller (though only when needswal is
1400 : : * true). Also sets *updatedbuflen to the final size of the buffer. This
1401 : : * buffer is used by caller when WAL logging is required.
1402 : : */
1403 : : static char *
1404 : 127 : _bt_delitems_update(BTVacuumPosting *updatable, int nupdatable,
1405 : : OffsetNumber *updatedoffsets, Size *updatedbuflen,
1406 : : bool needswal)
1407 : : {
1408 : 127 : char *updatedbuf = NULL;
1409 : 127 : Size buflen = 0;
1410 : :
1411 : : /* Shouldn't be called unless there's something to do */
1412 [ + - ]: 127 : Assert(nupdatable > 0);
1413 : :
1414 [ + + ]: 1532 : for (int i = 0; i < nupdatable; i++)
1415 : : {
1416 : 1405 : BTVacuumPosting vacposting = updatable[i];
1417 : 1405 : Size itemsz;
1418 : :
1419 : : /* Replace work area IndexTuple with updated version */
1420 : 1405 : _bt_update_posting(vacposting);
1421 : :
1422 : : /* Keep track of size of xl_btree_update for updatedbuf in passing */
1423 : 1405 : itemsz = SizeOfBtreeUpdate + vacposting->ndeletedtids * sizeof(uint16);
1424 : 1405 : buflen += itemsz;
1425 : :
1426 : : /* Build updatedoffsets buffer in passing */
1427 : 1405 : updatedoffsets[i] = vacposting->updatedoffset;
1428 : 1405 : }
1429 : :
1430 : : /* XLOG stuff */
1431 [ - + ]: 127 : if (needswal)
1432 : : {
1433 : 127 : Size offset = 0;
1434 : :
1435 : : /* Allocate, set final size for caller */
1436 : 127 : updatedbuf = palloc(buflen);
1437 : 127 : *updatedbuflen = buflen;
1438 [ + + ]: 1532 : for (int i = 0; i < nupdatable; i++)
1439 : : {
1440 : 1405 : BTVacuumPosting vacposting = updatable[i];
1441 : 1405 : Size itemsz;
1442 : 1405 : xl_btree_update update;
1443 : :
1444 : 1405 : update.ndeletedtids = vacposting->ndeletedtids;
1445 : 1405 : memcpy(updatedbuf + offset, &update.ndeletedtids,
1446 : : SizeOfBtreeUpdate);
1447 : 1405 : offset += SizeOfBtreeUpdate;
1448 : :
1449 : 1405 : itemsz = update.ndeletedtids * sizeof(uint16);
1450 : 1405 : memcpy(updatedbuf + offset, vacposting->deletetids, itemsz);
1451 : 1405 : offset += itemsz;
1452 : 1405 : }
1453 : 127 : }
1454 : :
1455 : 254 : return updatedbuf;
1456 : 127 : }
1457 : :
1458 : : /*
1459 : : * Comparator used by _bt_delitems_delete_check() to restore deltids array
1460 : : * back to its original leaf-page-wise sort order
1461 : : */
1462 : : static int
1463 : 506683 : _bt_delitems_cmp(const void *a, const void *b)
1464 : : {
1465 : 506683 : const TM_IndexDelete *indexdelete1 = a;
1466 : 506683 : const TM_IndexDelete *indexdelete2 = b;
1467 : :
1468 [ + - ]: 506683 : Assert(indexdelete1->id != indexdelete2->id);
1469 : :
1470 : 1013366 : return pg_cmp_s16(indexdelete1->id, indexdelete2->id);
1471 : 506683 : }
1472 : :
1473 : : /*
1474 : : * Try to delete item(s) from a btree leaf page during single-page cleanup.
1475 : : *
1476 : : * nbtree interface to table_index_delete_tuples(). Deletes a subset of index
1477 : : * tuples from caller's deltids array: those whose TIDs are found safe to
1478 : : * delete by the tableam (or already marked LP_DEAD in index, and so already
1479 : : * known to be deletable by our simple index deletion caller). We physically
1480 : : * delete index tuples from buf leaf page last of all (for index tuples where
1481 : : * that is known to be safe following our table_index_delete_tuples() call).
1482 : : *
1483 : : * Simple index deletion caller only includes TIDs from index tuples marked
1484 : : * LP_DEAD, as well as extra TIDs it found on the same leaf page that can be
1485 : : * included without increasing the total number of distinct table blocks for
1486 : : * the deletion operation as a whole. This approach often allows us to delete
1487 : : * some extra index tuples that were practically free for tableam to check in
1488 : : * passing (when they actually turn out to be safe to delete). It probably
1489 : : * only makes sense for the tableam to go ahead with these extra checks when
1490 : : * it is block-oriented (otherwise the checks probably won't be practically
1491 : : * free, which we rely on). The tableam interface requires the tableam side
1492 : : * to handle the problem, though, so this is okay (we as an index AM are free
1493 : : * to make the simplifying assumption that all tableams must be block-based).
1494 : : *
1495 : : * Bottom-up index deletion caller provides all the TIDs from the leaf page,
1496 : : * without expecting that tableam will check most of them. The tableam has
1497 : : * considerable discretion around which entries/blocks it checks. Our role in
1498 : : * costing the bottom-up deletion operation is strictly advisory.
1499 : : *
1500 : : * Note: Caller must have added deltids entries (i.e. entries that go in
1501 : : * delstate's main array) in leaf-page-wise order: page offset number order,
1502 : : * TID order among entries taken from the same posting list tuple (tiebreak on
1503 : : * TID). This order is convenient to work with here.
1504 : : *
1505 : : * Note: We also rely on the id field of each deltids element "capturing" this
1506 : : * original leaf-page-wise order. That is, we expect to be able to get back
1507 : : * to the original leaf-page-wise order just by sorting deltids on the id
1508 : : * field (tableam will sort deltids for its own reasons, so we'll need to put
1509 : : * it back in leaf-page-wise order afterwards).
1510 : : */
1511 : : void
1512 : 1037 : _bt_delitems_delete_check(Relation rel, Buffer buf, Relation heapRel,
1513 : : TM_IndexDeleteOp *delstate)
1514 : : {
1515 : 1037 : Page page = BufferGetPage(buf);
1516 : 1037 : TransactionId snapshotConflictHorizon;
1517 : 1037 : bool isCatalogRel;
1518 : 1037 : OffsetNumber postingidxoffnum = InvalidOffsetNumber;
1519 : 1037 : int ndeletable = 0,
1520 : 1037 : nupdatable = 0;
1521 : 1037 : OffsetNumber deletable[MaxIndexTuplesPerPage];
1522 : 1037 : BTVacuumPosting updatable[MaxIndexTuplesPerPage];
1523 : :
1524 : : /* Use tableam interface to determine which tuples to delete first */
1525 : 1037 : snapshotConflictHorizon = table_index_delete_tuples(heapRel, delstate);
1526 [ + - - + : 1037 : isCatalogRel = RelationIsAccessibleInLogicalDecoding(heapRel);
# # # # #
# # # # #
# # # # ]
1527 : :
1528 : : /* Should not WAL-log snapshotConflictHorizon unless it's required */
1529 [ + + ]: 1037 : if (!XLogStandbyInfoActive())
1530 : 1026 : snapshotConflictHorizon = InvalidTransactionId;
1531 : :
1532 : : /*
1533 : : * Construct a leaf-page-wise description of what _bt_delitems_delete()
1534 : : * needs to do to physically delete index tuples from the page.
1535 : : *
1536 : : * Must sort deltids array to restore leaf-page-wise order (original order
1537 : : * before call to tableam). This is the order that the loop expects.
1538 : : *
1539 : : * Note that deltids array might be a lot smaller now. It might even have
1540 : : * no entries at all (with bottom-up deletion caller), in which case there
1541 : : * is nothing left to do.
1542 : : */
1543 : 1037 : qsort(delstate->deltids, delstate->ndeltids, sizeof(TM_IndexDelete),
1544 : : _bt_delitems_cmp);
1545 [ + + ]: 1037 : if (delstate->ndeltids == 0)
1546 : : {
1547 [ + - ]: 152 : Assert(delstate->bottomup);
1548 : 152 : return;
1549 : : }
1550 : :
1551 : : /* We definitely have to delete at least one index tuple (or one TID) */
1552 [ + + ]: 73426 : for (int i = 0; i < delstate->ndeltids; i++)
1553 : : {
1554 : 72541 : TM_IndexStatus *dstatus = delstate->status + delstate->deltids[i].id;
1555 : 72541 : OffsetNumber idxoffnum = dstatus->idxoffnum;
1556 : 72541 : ItemId itemid = PageGetItemId(page, idxoffnum);
1557 : 72541 : IndexTuple itup = (IndexTuple) PageGetItem(page, itemid);
1558 : 72541 : int nestedi,
1559 : : nitem;
1560 : 72541 : BTVacuumPosting vacposting;
1561 : :
1562 [ - + + - ]: 72541 : Assert(OffsetNumberIsValid(idxoffnum));
1563 : :
1564 [ + + ]: 72541 : if (idxoffnum == postingidxoffnum)
1565 : : {
1566 : : /*
1567 : : * This deltid entry is a TID from a posting list tuple that has
1568 : : * already been completely processed
1569 : : */
1570 [ - + ]: 2445 : Assert(BTreeTupleIsPosting(itup));
1571 [ - + ]: 2445 : Assert(ItemPointerCompare(BTreeTupleGetHeapTID(itup),
1572 : : &delstate->deltids[i].tid) < 0);
1573 [ - + ]: 2445 : Assert(ItemPointerCompare(BTreeTupleGetMaxHeapTID(itup),
1574 : : &delstate->deltids[i].tid) >= 0);
1575 : 2445 : continue;
1576 : : }
1577 : :
1578 [ + + ]: 70096 : if (!BTreeTupleIsPosting(itup))
1579 : : {
1580 : : /* Plain non-pivot tuple */
1581 [ - + ]: 68822 : Assert(ItemPointerEquals(&itup->t_tid, &delstate->deltids[i].tid));
1582 [ + + ]: 68822 : if (dstatus->knowndeletable)
1583 : 53978 : deletable[ndeletable++] = idxoffnum;
1584 : 68822 : continue;
1585 : : }
1586 : :
1587 : : /*
1588 : : * itup is a posting list tuple whose lowest deltids entry (which may
1589 : : * or may not be for the first TID from itup) is considered here now.
1590 : : * We should process all of the deltids entries for the posting list
1591 : : * together now, though (not just the lowest). Remember to skip over
1592 : : * later itup-related entries during later iterations of outermost
1593 : : * loop.
1594 : : */
1595 : 1274 : postingidxoffnum = idxoffnum; /* Remember work in outermost loop */
1596 : 1274 : nestedi = i; /* Initialize for first itup deltids entry */
1597 : 1274 : vacposting = NULL; /* Describes final action for itup */
1598 : 1274 : nitem = BTreeTupleGetNPosting(itup);
1599 [ + + ]: 6996 : for (int p = 0; p < nitem; p++)
1600 : : {
1601 : 5722 : ItemPointer ptid = BTreeTupleGetPostingN(itup, p);
1602 : 5722 : int ptidcmp = -1;
1603 : :
1604 : : /*
1605 : : * This nested loop reuses work across ptid TIDs taken from itup.
1606 : : * We take advantage of the fact that both itup's TIDs and deltids
1607 : : * entries (within a single itup/posting list grouping) must both
1608 : : * be in ascending TID order.
1609 : : */
1610 [ + + ]: 8601 : for (; nestedi < delstate->ndeltids; nestedi++)
1611 : : {
1612 : 8456 : TM_IndexDelete *tcdeltid = &delstate->deltids[nestedi];
1613 : 8456 : TM_IndexStatus *tdstatus = (delstate->status + tcdeltid->id);
1614 : :
1615 : : /* Stop once we get past all itup related deltids entries */
1616 [ - + ]: 8456 : Assert(tdstatus->idxoffnum >= idxoffnum);
1617 [ + + ]: 8456 : if (tdstatus->idxoffnum != idxoffnum)
1618 : 1355 : break;
1619 : :
1620 : : /* Skip past non-deletable itup related entries up front */
1621 [ + + ]: 7101 : if (!tdstatus->knowndeletable)
1622 : 1112 : continue;
1623 : :
1624 : : /* Entry is first partial ptid match (or an exact match)? */
1625 : 5989 : ptidcmp = ItemPointerCompare(&tcdeltid->tid, ptid);
1626 [ + + ]: 5989 : if (ptidcmp >= 0)
1627 : : {
1628 : : /* Greater than or equal (partial or exact) match... */
1629 : 4222 : break;
1630 : : }
1631 [ + + + ]: 8456 : }
1632 : :
1633 : : /* ...exact ptid match to a deletable deltids entry? */
1634 [ + + ]: 5722 : if (ptidcmp != 0)
1635 : 3115 : continue;
1636 : :
1637 : : /* Exact match for deletable deltids entry -- ptid gets deleted */
1638 [ + + ]: 2607 : if (vacposting == NULL)
1639 : : {
1640 : 923 : vacposting = palloc(offsetof(BTVacuumPostingData, deletetids) +
1641 : 923 : nitem * sizeof(uint16));
1642 : 923 : vacposting->itup = itup;
1643 : 923 : vacposting->updatedoffset = idxoffnum;
1644 : 923 : vacposting->ndeletedtids = 0;
1645 : 923 : }
1646 : 2607 : vacposting->deletetids[vacposting->ndeletedtids++] = p;
1647 [ + + ]: 5722 : }
1648 : :
1649 : : /* Final decision on itup, a posting list tuple */
1650 : :
1651 [ + + ]: 1274 : if (vacposting == NULL)
1652 : : {
1653 : : /* No TIDs to delete from itup -- do nothing */
1654 : 351 : }
1655 [ + + ]: 923 : else if (vacposting->ndeletedtids == nitem)
1656 : : {
1657 : : /* Straight delete of itup (to delete all TIDs) */
1658 : 651 : deletable[ndeletable++] = idxoffnum;
1659 : : /* Turns out we won't need granular information */
1660 : 651 : pfree(vacposting);
1661 : 651 : }
1662 : : else
1663 : : {
1664 : : /* Delete some (but not all) TIDs from itup */
1665 [ + - ]: 272 : Assert(vacposting->ndeletedtids > 0 &&
1666 : : vacposting->ndeletedtids < nitem);
1667 : 272 : updatable[nupdatable++] = vacposting;
1668 : : }
1669 [ + + ]: 72541 : }
1670 : :
1671 : : /* Physically delete tuples (or TIDs) using deletable (or updatable) */
1672 : 1770 : _bt_delitems_delete(rel, buf, snapshotConflictHorizon, isCatalogRel,
1673 : 885 : deletable, ndeletable, updatable, nupdatable);
1674 : :
1675 : : /* be tidy */
1676 [ + + ]: 1157 : for (int i = 0; i < nupdatable; i++)
1677 : 272 : pfree(updatable[i]);
1678 : 1037 : }
1679 : :
1680 : : /*
1681 : : * Check that leftsib page (the btpo_prev of target page) is not marked with
1682 : : * INCOMPLETE_SPLIT flag. Used during page deletion.
1683 : : *
1684 : : * Returning true indicates that page flag is set in leftsib (which is
1685 : : * definitely still the left sibling of target). When that happens, the
1686 : : * target doesn't have a downlink in parent, and the page deletion algorithm
1687 : : * isn't prepared to handle that. Deletion of the target page (or the whole
1688 : : * subtree that contains the target page) cannot take place.
1689 : : *
1690 : : * Caller should not have a lock on the target page itself, since pages on the
1691 : : * same level must always be locked left to right to avoid deadlocks.
1692 : : */
1693 : : static bool
1694 : 201 : _bt_leftsib_splitflag(Relation rel, BlockNumber leftsib, BlockNumber target)
1695 : : {
1696 : 201 : Buffer buf;
1697 : 201 : Page page;
1698 : 201 : BTPageOpaque opaque;
1699 : 201 : bool result;
1700 : :
1701 : : /* Easy case: No left sibling */
1702 [ + + ]: 201 : if (leftsib == P_NONE)
1703 : 124 : return false;
1704 : :
1705 : 77 : buf = _bt_getbuf(rel, leftsib, BT_READ);
1706 : 77 : page = BufferGetPage(buf);
1707 : 77 : opaque = BTPageGetOpaque(page);
1708 : :
1709 : : /*
1710 : : * If the left sibling was concurrently split, so that its next-pointer
1711 : : * doesn't point to the current page anymore, the split that created
1712 : : * target must be completed. Caller can reasonably expect that there will
1713 : : * be a downlink to the target page that it can relocate using its stack.
1714 : : * (We don't allow splitting an incompletely split page again until the
1715 : : * previous split has been completed.)
1716 : : */
1717 [ - + ]: 77 : result = (opaque->btpo_next == target && P_INCOMPLETE_SPLIT(opaque));
1718 : 77 : _bt_relbuf(rel, buf);
1719 : :
1720 : 77 : return result;
1721 : 201 : }
1722 : :
1723 : : /*
1724 : : * Check that leafrightsib page (the btpo_next of target leaf page) is not
1725 : : * marked with ISHALFDEAD flag. Used during page deletion.
1726 : : *
1727 : : * Returning true indicates that page flag is set in leafrightsib, so page
1728 : : * deletion cannot go ahead. Our caller is not prepared to deal with the case
1729 : : * where the parent page does not have a pivot tuples whose downlink points to
1730 : : * leafrightsib (due to an earlier interrupted VACUUM operation). It doesn't
1731 : : * seem worth going to the trouble of teaching our caller to deal with it.
1732 : : * The situation will be resolved after VACUUM finishes the deletion of the
1733 : : * half-dead page (when a future VACUUM operation reaches the target page
1734 : : * again).
1735 : : *
1736 : : * _bt_leftsib_splitflag() is called for both leaf pages and internal pages.
1737 : : * _bt_rightsib_halfdeadflag() is only called for leaf pages, though. This is
1738 : : * okay because of the restriction on deleting pages that are the rightmost
1739 : : * page of their parent (i.e. that such deletions can only take place when the
1740 : : * entire subtree must be deleted). The leaf level check made here will apply
1741 : : * to a right "cousin" leaf page rather than a simple right sibling leaf page
1742 : : * in cases where caller actually goes on to attempt deleting pages that are
1743 : : * above the leaf page. The right cousin leaf page is representative of the
1744 : : * left edge of the subtree to the right of the to-be-deleted subtree as a
1745 : : * whole, which is exactly the condition that our caller cares about.
1746 : : * (Besides, internal pages are never marked half-dead, so it isn't even
1747 : : * possible to _directly_ assess if an internal page is part of some other
1748 : : * to-be-deleted subtree.)
1749 : : */
1750 : : static bool
1751 : 151 : _bt_rightsib_halfdeadflag(Relation rel, BlockNumber leafrightsib)
1752 : : {
1753 : 151 : Buffer buf;
1754 : 151 : Page page;
1755 : 151 : BTPageOpaque opaque;
1756 : 151 : bool result;
1757 : :
1758 [ + - ]: 151 : Assert(leafrightsib != P_NONE);
1759 : :
1760 : 151 : buf = _bt_getbuf(rel, leafrightsib, BT_READ);
1761 : 151 : page = BufferGetPage(buf);
1762 : 151 : opaque = BTPageGetOpaque(page);
1763 : :
1764 [ + - ]: 151 : Assert(P_ISLEAF(opaque) && !P_ISDELETED(opaque));
1765 : 151 : result = P_ISHALFDEAD(opaque);
1766 : 151 : _bt_relbuf(rel, buf);
1767 : :
1768 : 302 : return result;
1769 : 151 : }
1770 : :
1771 : : /*
1772 : : * _bt_pagedel() -- Delete a leaf page from the b-tree, if legal to do so.
1773 : : *
1774 : : * This action unlinks the leaf page from the b-tree structure, removing all
1775 : : * pointers leading to it --- but not touching its own left and right links.
1776 : : * The page cannot be physically reclaimed right away, since other processes
1777 : : * may currently be trying to follow links leading to the page; they have to
1778 : : * be allowed to use its right-link to recover. See nbtree/README.
1779 : : *
1780 : : * On entry, the target buffer must be pinned and locked (either read or write
1781 : : * lock is OK). The page must be an empty leaf page, which may be half-dead
1782 : : * already (a half-dead page should only be passed to us when an earlier
1783 : : * VACUUM operation was interrupted, though). Note in particular that caller
1784 : : * should never pass a buffer containing an existing deleted page here. The
1785 : : * lock and pin on caller's buffer will be dropped before we return.
1786 : : *
1787 : : * Maintains bulk delete stats for caller, which are taken from vstate. We
1788 : : * need to cooperate closely with caller here so that whole VACUUM operation
1789 : : * reliably avoids any double counting of subsidiary-to-leafbuf pages that we
1790 : : * delete in passing. If such pages happen to be from a block number that is
1791 : : * ahead of the current scanblkno position, then caller is expected to count
1792 : : * them directly later on. It's simpler for us to understand caller's
1793 : : * requirements than it would be for caller to understand when or how a
1794 : : * deleted page became deleted after the fact.
1795 : : *
1796 : : * NOTE: this leaks memory. Rather than trying to clean up everything
1797 : : * carefully, it's better to run it in a temp context that can be reset
1798 : : * frequently.
1799 : : */
1800 : : void
1801 : 164 : _bt_pagedel(Relation rel, Buffer leafbuf, BTVacState *vstate)
1802 : : {
1803 : 164 : BlockNumber rightsib;
1804 : 164 : bool rightsib_empty;
1805 : 164 : Page page;
1806 : 164 : BTPageOpaque opaque;
1807 : :
1808 : : /*
1809 : : * Save original leafbuf block number from caller. Only deleted blocks
1810 : : * that are <= scanblkno are added to bulk delete stat's pages_deleted
1811 : : * count.
1812 : : */
1813 : 164 : BlockNumber scanblkno = BufferGetBlockNumber(leafbuf);
1814 : :
1815 : : /*
1816 : : * "stack" is a search stack leading (approximately) to the target page.
1817 : : * It is initially NULL, but when iterating, we keep it to avoid
1818 : : * duplicated search effort.
1819 : : *
1820 : : * Also, when "stack" is not NULL, we have already checked that the
1821 : : * current page is not the right half of an incomplete split, i.e. the
1822 : : * left sibling does not have its INCOMPLETE_SPLIT flag set, including
1823 : : * when the current target page is to the right of caller's initial page
1824 : : * (the scanblkno page).
1825 : : */
1826 : 164 : BTStack stack = NULL;
1827 : :
1828 : 167 : for (;;)
1829 : : {
1830 : 315 : page = BufferGetPage(leafbuf);
1831 : 315 : opaque = BTPageGetOpaque(page);
1832 : :
1833 : : /*
1834 : : * Internal pages are never deleted directly, only as part of deleting
1835 : : * the whole subtree all the way down to leaf level.
1836 : : *
1837 : : * Also check for deleted pages here. Caller never passes us a fully
1838 : : * deleted page. Only VACUUM can delete pages, so there can't have
1839 : : * been a concurrent deletion. Assume that we reached any deleted
1840 : : * page encountered here by following a sibling link, and that the
1841 : : * index is corrupt.
1842 : : */
1843 [ + - ]: 315 : Assert(!P_ISDELETED(opaque));
1844 [ + - - + ]: 315 : if (!P_ISLEAF(opaque) || P_ISDELETED(opaque))
1845 : : {
1846 : : /*
1847 : : * Pre-9.4 page deletion only marked internal pages as half-dead,
1848 : : * but now we only use that flag on leaf pages. The old algorithm
1849 : : * was never supposed to leave half-dead pages in the tree, it was
1850 : : * just a transient state, but it was nevertheless possible in
1851 : : * error scenarios. We don't know how to deal with them here. They
1852 : : * are harmless as far as searches are considered, but inserts
1853 : : * into the deleted keyspace could add out-of-order downlinks in
1854 : : * the upper levels. Log a notice, hopefully the admin will notice
1855 : : * and reindex.
1856 : : */
1857 [ # # ]: 0 : if (P_ISHALFDEAD(opaque))
1858 [ # # # # ]: 0 : ereport(LOG,
1859 : : (errcode(ERRCODE_INDEX_CORRUPTED),
1860 : : errmsg("index \"%s\" contains a half-dead internal page",
1861 : : RelationGetRelationName(rel)),
1862 : : errhint("This can be caused by an interrupted VACUUM in version 9.3 or older, before upgrade. Please REINDEX it.")));
1863 : :
1864 [ # # ]: 0 : if (P_ISDELETED(opaque))
1865 [ # # # # ]: 0 : ereport(LOG,
1866 : : (errcode(ERRCODE_INDEX_CORRUPTED),
1867 : : errmsg_internal("found deleted block %u while following right link from block %u in index \"%s\"",
1868 : : BufferGetBlockNumber(leafbuf),
1869 : : scanblkno,
1870 : : RelationGetRelationName(rel))));
1871 : :
1872 : 0 : _bt_relbuf(rel, leafbuf);
1873 : 0 : return;
1874 : : }
1875 : :
1876 : : /*
1877 : : * We can never delete rightmost pages nor root pages. While at it,
1878 : : * check that page is empty, since it's possible that the leafbuf page
1879 : : * was empty a moment ago, but has since had some inserts.
1880 : : *
1881 : : * To keep the algorithm simple, we also never delete an incompletely
1882 : : * split page (they should be rare enough that this doesn't make any
1883 : : * meaningful difference to disk usage):
1884 : : *
1885 : : * The INCOMPLETE_SPLIT flag on the page tells us if the page is the
1886 : : * left half of an incomplete split, but ensuring that it's not the
1887 : : * right half is more complicated. For that, we have to check that
1888 : : * the left sibling doesn't have its INCOMPLETE_SPLIT flag set using
1889 : : * _bt_leftsib_splitflag(). On the first iteration, we temporarily
1890 : : * release the lock on scanblkno/leafbuf, check the left sibling, and
1891 : : * construct a search stack to scanblkno. On subsequent iterations,
1892 : : * we know we stepped right from a page that passed these tests, so
1893 : : * it's OK.
1894 : : */
1895 [ + + + - ]: 315 : if (P_RIGHTMOST(opaque) || P_ISROOT(opaque) ||
1896 [ + - - + ]: 299 : P_FIRSTDATAKEY(opaque) <= PageGetMaxOffsetNumber(page) ||
1897 : 299 : P_INCOMPLETE_SPLIT(opaque))
1898 : : {
1899 : : /* Should never fail to delete a half-dead page */
1900 [ + - ]: 16 : Assert(!P_ISHALFDEAD(opaque));
1901 : :
1902 : 16 : _bt_relbuf(rel, leafbuf);
1903 : 16 : return;
1904 : : }
1905 : :
1906 : : /*
1907 : : * First, remove downlink pointing to the page (or a parent of the
1908 : : * page, if we are going to delete a taller subtree), and mark the
1909 : : * leafbuf page half-dead
1910 : : */
1911 [ - + ]: 299 : if (!P_ISHALFDEAD(opaque))
1912 : : {
1913 : : /*
1914 : : * We need an approximate pointer to the page's parent page. We
1915 : : * use a variant of the standard search mechanism to search for
1916 : : * the page's high key; this will give us a link to either the
1917 : : * current parent or someplace to its left (if there are multiple
1918 : : * equal high keys, which is possible with !heapkeyspace indexes).
1919 : : *
1920 : : * Also check if this is the right-half of an incomplete split
1921 : : * (see comment above).
1922 : : */
1923 [ + + ]: 299 : if (!stack)
1924 : : {
1925 : 148 : BTScanInsert itup_key;
1926 : 148 : ItemId itemid;
1927 : 148 : IndexTuple targetkey;
1928 : 148 : BlockNumber leftsib,
1929 : : leafblkno;
1930 : 148 : Buffer sleafbuf;
1931 : :
1932 : 148 : itemid = PageGetItemId(page, P_HIKEY);
1933 : 148 : targetkey = CopyIndexTuple((IndexTuple) PageGetItem(page, itemid));
1934 : :
1935 : 148 : leftsib = opaque->btpo_prev;
1936 : 148 : leafblkno = BufferGetBlockNumber(leafbuf);
1937 : :
1938 : : /*
1939 : : * To avoid deadlocks, we'd better drop the leaf page lock
1940 : : * before going further.
1941 : : */
1942 : 148 : _bt_unlockbuf(rel, leafbuf);
1943 : :
1944 : : /*
1945 : : * Check that the left sibling of leafbuf (if any) is not
1946 : : * marked with INCOMPLETE_SPLIT flag before proceeding
1947 : : */
1948 [ - + ]: 148 : Assert(leafblkno == scanblkno);
1949 [ - + ]: 148 : if (_bt_leftsib_splitflag(rel, leftsib, leafblkno))
1950 : : {
1951 : 0 : ReleaseBuffer(leafbuf);
1952 : 0 : return;
1953 : : }
1954 : :
1955 : : /*
1956 : : * We need an insertion scan key, so build one.
1957 : : *
1958 : : * _bt_search searches for the leaf page that contains any
1959 : : * matching non-pivot tuples, but we need it to "search" for
1960 : : * the high key pivot from the page that we're set to delete.
1961 : : * Compensate for the mismatch by having _bt_search locate the
1962 : : * last position < equal-to-untruncated-prefix non-pivots.
1963 : : */
1964 : 148 : itup_key = _bt_mkscankey(rel, targetkey);
1965 : :
1966 : : /* Set up a BTLessStrategyNumber-like insertion scan key */
1967 : 148 : itup_key->nextkey = false;
1968 : 148 : itup_key->backward = true;
1969 : 148 : stack = _bt_search(rel, NULL, itup_key, &sleafbuf, BT_READ);
1970 : : /* won't need a second lock or pin on leafbuf */
1971 : 148 : _bt_relbuf(rel, sleafbuf);
1972 : :
1973 : : /*
1974 : : * Re-lock the leaf page, and start over to use our stack
1975 : : * within _bt_mark_page_halfdead. We must do it that way
1976 : : * because it's possible that leafbuf can no longer be
1977 : : * deleted. We need to recheck.
1978 : : *
1979 : : * Note: We can't simply hold on to the sleafbuf lock instead,
1980 : : * because it's barely possible that sleafbuf is not the same
1981 : : * page as leafbuf. This happens when leafbuf split after our
1982 : : * original lock was dropped, but before _bt_search finished
1983 : : * its descent. We rely on the assumption that we'll find
1984 : : * leafbuf isn't safe to delete anymore in this scenario.
1985 : : * (Page deletion can cope with the stack being to the left of
1986 : : * leafbuf, but not to the right of leafbuf.)
1987 : : */
1988 : 148 : _bt_lockbuf(rel, leafbuf, BT_WRITE);
1989 : 148 : continue;
1990 [ + - ]: 148 : }
1991 : :
1992 : : /*
1993 : : * See if it's safe to delete the leaf page, and determine how
1994 : : * many parent/internal pages above the leaf level will be
1995 : : * deleted. If it's safe then _bt_mark_page_halfdead will also
1996 : : * perform the first phase of deletion, which includes marking the
1997 : : * leafbuf page half-dead.
1998 : : */
1999 [ + - ]: 151 : Assert(P_ISLEAF(opaque) && !P_IGNORE(opaque));
2000 [ + + + + ]: 302 : if (!_bt_mark_page_halfdead(rel, vstate->info->heaprel, leafbuf,
2001 : 151 : stack))
2002 : : {
2003 : 3 : _bt_relbuf(rel, leafbuf);
2004 : 3 : return;
2005 : : }
2006 : 148 : }
2007 : : else
2008 : : {
2009 : : INJECTION_POINT("nbtree-finish-half-dead-page-vacuum", NULL);
2010 : : }
2011 : :
2012 : : /*
2013 : : * Then unlink it from its siblings. Each call to
2014 : : * _bt_unlink_halfdead_page unlinks the topmost page from the subtree,
2015 : : * making it shallower. Iterate until the leafbuf page is deleted.
2016 : : */
2017 : 148 : rightsib_empty = false;
2018 [ + - ]: 148 : Assert(P_ISLEAF(opaque) && P_ISHALFDEAD(opaque));
2019 [ + + ]: 342 : while (P_ISHALFDEAD(opaque))
2020 : : {
2021 : : /* Check for interrupts in _bt_unlink_halfdead_page */
2022 [ + - + - ]: 388 : if (!_bt_unlink_halfdead_page(rel, leafbuf, scanblkno,
2023 : 194 : &rightsib_empty, vstate))
2024 : : {
2025 : : /*
2026 : : * _bt_unlink_halfdead_page should never fail, since we
2027 : : * established that deletion is generally safe in
2028 : : * _bt_mark_page_halfdead -- index must be corrupt.
2029 : : *
2030 : : * Note that _bt_unlink_halfdead_page already released the
2031 : : * lock and pin on leafbuf for us.
2032 : : */
2033 : 0 : Assert(false);
2034 : 0 : return;
2035 : : }
2036 : : }
2037 : :
2038 [ + - ]: 148 : Assert(P_ISLEAF(opaque) && P_ISDELETED(opaque));
2039 : :
2040 : 148 : rightsib = opaque->btpo_next;
2041 : :
2042 : 148 : _bt_relbuf(rel, leafbuf);
2043 : :
2044 : : /*
2045 : : * Check here, as calling loops will have locks held, preventing
2046 : : * interrupts from being processed.
2047 : : */
2048 [ + - ]: 148 : CHECK_FOR_INTERRUPTS();
2049 : :
2050 : : /*
2051 : : * The page has now been deleted. If its right sibling is completely
2052 : : * empty, it's possible that the reason we haven't deleted it earlier
2053 : : * is that it was the rightmost child of the parent. Now that we
2054 : : * removed the downlink for this page, the right sibling might now be
2055 : : * the only child of the parent, and could be removed. It would be
2056 : : * picked up by the next vacuum anyway, but might as well try to
2057 : : * remove it now, so loop back to process the right sibling.
2058 : : *
2059 : : * Note: This relies on the assumption that _bt_getstackbuf() will be
2060 : : * able to reuse our original descent stack with a different child
2061 : : * block (provided that the child block is to the right of the
2062 : : * original leaf page reached by _bt_search()). It will even update
2063 : : * the descent stack each time we loop around, avoiding repeated work.
2064 : : */
2065 [ + + ]: 148 : if (!rightsib_empty)
2066 : 145 : break;
2067 : :
2068 : 3 : leafbuf = _bt_getbuf(rel, rightsib, BT_WRITE);
2069 : : }
2070 [ - + ]: 164 : }
2071 : :
2072 : : /*
2073 : : * First stage of page deletion.
2074 : : *
2075 : : * Establish the height of the to-be-deleted subtree with leafbuf at its
2076 : : * lowest level, remove the downlink to the subtree, and mark leafbuf
2077 : : * half-dead. The final to-be-deleted subtree is usually just leafbuf itself,
2078 : : * but may include additional internal pages (at most one per level of the
2079 : : * tree below the root).
2080 : : *
2081 : : * Caller must pass a valid heaprel, since it's just about possible that our
2082 : : * call to _bt_lock_subtree_parent will need to allocate a new index page to
2083 : : * complete a page split. Every call to _bt_allocbuf needs to pass a heaprel.
2084 : : *
2085 : : * Returns 'false' if leafbuf is unsafe to delete, usually because leafbuf is
2086 : : * the rightmost child of its parent (and parent has more than one downlink).
2087 : : * Returns 'true' when the first stage of page deletion completed
2088 : : * successfully.
2089 : : */
2090 : : static bool
2091 : 151 : _bt_mark_page_halfdead(Relation rel, Relation heaprel, Buffer leafbuf,
2092 : : BTStack stack)
2093 : : {
2094 : 151 : BlockNumber leafblkno;
2095 : 151 : BlockNumber leafrightsib;
2096 : 151 : BlockNumber topparent;
2097 : 151 : BlockNumber topparentrightsib;
2098 : 151 : ItemId itemid;
2099 : 151 : Page page;
2100 : 151 : BTPageOpaque opaque;
2101 : 151 : Buffer subtreeparent;
2102 : 151 : OffsetNumber poffset;
2103 : 151 : OffsetNumber nextoffset;
2104 : 151 : IndexTuple itup;
2105 : 151 : IndexTupleData trunctuple;
2106 : :
2107 : 151 : page = BufferGetPage(leafbuf);
2108 : 151 : opaque = BTPageGetOpaque(page);
2109 : :
2110 [ + - ]: 151 : Assert(!P_RIGHTMOST(opaque) && !P_ISROOT(opaque) &&
2111 : : P_ISLEAF(opaque) && !P_IGNORE(opaque) &&
2112 : : P_FIRSTDATAKEY(opaque) > PageGetMaxOffsetNumber(page));
2113 [ + - ]: 151 : Assert(heaprel != NULL);
2114 : :
2115 : : /*
2116 : : * Save info about the leaf page.
2117 : : */
2118 : 151 : leafblkno = BufferGetBlockNumber(leafbuf);
2119 : 151 : leafrightsib = opaque->btpo_next;
2120 : :
2121 : : /*
2122 : : * Before attempting to lock the parent page, check that the right sibling
2123 : : * is not in half-dead state. A half-dead right sibling would have no
2124 : : * downlink in the parent, which would be highly confusing later when we
2125 : : * delete the downlink. It would fail the "right sibling of target page
2126 : : * is also the next child in parent page" cross-check below.
2127 : : */
2128 [ - + ]: 151 : if (_bt_rightsib_halfdeadflag(rel, leafrightsib))
2129 : : {
2130 [ # # # # ]: 0 : elog(DEBUG1, "could not delete page %u because its right sibling %u is half-dead",
2131 : : leafblkno, leafrightsib);
2132 : 0 : return false;
2133 : : }
2134 : :
2135 : : /*
2136 : : * We cannot delete a page that is the rightmost child of its immediate
2137 : : * parent, unless it is the only child --- in which case the parent has to
2138 : : * be deleted too, and the same condition applies recursively to it. We
2139 : : * have to check this condition all the way up before trying to delete,
2140 : : * and lock the parent of the root of the to-be-deleted subtree (the
2141 : : * "subtree parent"). _bt_lock_subtree_parent() locks the subtree parent
2142 : : * for us. We remove the downlink to the "top parent" page (subtree root
2143 : : * page) from the subtree parent page below.
2144 : : *
2145 : : * Initialize topparent to be leafbuf page now. The final to-be-deleted
2146 : : * subtree is often a degenerate one page subtree consisting only of the
2147 : : * leafbuf page. When that happens, the leafbuf page is the final subtree
2148 : : * root page/top parent page.
2149 : : */
2150 : 151 : topparent = leafblkno;
2151 : 151 : topparentrightsib = leafrightsib;
2152 [ + + ]: 151 : if (!_bt_lock_subtree_parent(rel, heaprel, leafblkno, stack,
2153 : : &subtreeparent, &poffset,
2154 : : &topparent, &topparentrightsib))
2155 : 3 : return false;
2156 : :
2157 : 148 : page = BufferGetPage(subtreeparent);
2158 : 148 : opaque = BTPageGetOpaque(page);
2159 : :
2160 : : #ifdef USE_ASSERT_CHECKING
2161 : :
2162 : : /*
2163 : : * This is just an assertion because _bt_lock_subtree_parent should have
2164 : : * guaranteed tuple has the expected contents
2165 : : */
2166 : 148 : itemid = PageGetItemId(page, poffset);
2167 : 148 : itup = (IndexTuple) PageGetItem(page, itemid);
2168 [ + - ]: 148 : Assert(BTreeTupleGetDownLink(itup) == topparent);
2169 : : #endif
2170 : :
2171 : 148 : nextoffset = OffsetNumberNext(poffset);
2172 : 148 : itemid = PageGetItemId(page, nextoffset);
2173 : 148 : itup = (IndexTuple) PageGetItem(page, itemid);
2174 : :
2175 : : /*
2176 : : * Check that the parent-page index items we're about to delete/overwrite
2177 : : * in subtree parent page contain what we expect. This can fail if the
2178 : : * index has become corrupt for some reason. When that happens we back
2179 : : * out of deletion of the leafbuf subtree. (This is just like the case
2180 : : * where _bt_lock_subtree_parent() cannot "re-find" leafbuf's downlink.)
2181 : : */
2182 [ + - ]: 148 : if (BTreeTupleGetDownLink(itup) != topparentrightsib)
2183 : : {
2184 [ # # # # ]: 0 : ereport(LOG,
2185 : : (errcode(ERRCODE_INDEX_CORRUPTED),
2186 : : errmsg_internal("right sibling %u of block %u is not next child %u of block %u in index \"%s\"",
2187 : : topparentrightsib, topparent,
2188 : : BTreeTupleGetDownLink(itup),
2189 : : BufferGetBlockNumber(subtreeparent),
2190 : : RelationGetRelationName(rel))));
2191 : :
2192 : 0 : _bt_relbuf(rel, subtreeparent);
2193 : 0 : Assert(false);
2194 : 0 : return false;
2195 : : }
2196 : :
2197 : : /*
2198 : : * Any insert which would have gone on the leaf block will now go to its
2199 : : * right sibling. In other words, the key space moves right.
2200 : : */
2201 : 148 : PredicateLockPageCombine(rel, leafblkno, leafrightsib);
2202 : :
2203 : : /* No ereport(ERROR) until changes are logged */
2204 : 148 : START_CRIT_SECTION();
2205 : :
2206 : : /*
2207 : : * Update parent of subtree. We want to delete the downlink to the top
2208 : : * parent page/root of the subtree, and the *following* key. Easiest way
2209 : : * is to copy the right sibling's downlink over the downlink that points
2210 : : * to top parent page, and then delete the right sibling's original pivot
2211 : : * tuple.
2212 : : *
2213 : : * Lanin and Shasha make the key space move left when deleting a page,
2214 : : * whereas the key space moves right here. That's why we cannot simply
2215 : : * delete the pivot tuple with the downlink to the top parent page. See
2216 : : * nbtree/README.
2217 : : */
2218 : 148 : page = BufferGetPage(subtreeparent);
2219 : 148 : opaque = BTPageGetOpaque(page);
2220 : :
2221 : 148 : itemid = PageGetItemId(page, poffset);
2222 : 148 : itup = (IndexTuple) PageGetItem(page, itemid);
2223 : 148 : BTreeTupleSetDownLink(itup, topparentrightsib);
2224 : :
2225 : 148 : nextoffset = OffsetNumberNext(poffset);
2226 : 148 : PageIndexTupleDelete(page, nextoffset);
2227 : :
2228 : : /*
2229 : : * Mark the leaf page as half-dead, and stamp it with a link to the top
2230 : : * parent page. When the leaf page is also the top parent page, the link
2231 : : * is set to InvalidBlockNumber.
2232 : : */
2233 : 148 : page = BufferGetPage(leafbuf);
2234 : 148 : opaque = BTPageGetOpaque(page);
2235 : 148 : opaque->btpo_flags |= BTP_HALF_DEAD;
2236 : :
2237 [ + - ]: 148 : Assert(PageGetMaxOffsetNumber(page) == P_HIKEY);
2238 [ + - + - : 296 : MemSet(&trunctuple, 0, sizeof(IndexTupleData));
+ - - + +
+ ]
2239 : 148 : trunctuple.t_info = sizeof(IndexTupleData);
2240 [ + + ]: 148 : if (topparent != leafblkno)
2241 : 20 : BTreeTupleSetTopParent(&trunctuple, topparent);
2242 : : else
2243 : 128 : BTreeTupleSetTopParent(&trunctuple, InvalidBlockNumber);
2244 : :
2245 [ + - ]: 148 : if (!PageIndexTupleOverwrite(page, P_HIKEY, &trunctuple, IndexTupleSize(&trunctuple)))
2246 [ # # # # ]: 0 : elog(ERROR, "could not overwrite high key in half-dead page");
2247 : :
2248 : : /* Must mark buffers dirty before XLogInsert */
2249 : 148 : MarkBufferDirty(subtreeparent);
2250 : 148 : MarkBufferDirty(leafbuf);
2251 : :
2252 : : /* XLOG stuff */
2253 [ + - + - : 148 : if (RelationNeedsWAL(rel))
+ - - + ]
2254 : : {
2255 : 148 : xl_btree_mark_page_halfdead xlrec;
2256 : 148 : XLogRecPtr recptr;
2257 : :
2258 : 148 : xlrec.poffset = poffset;
2259 : 148 : xlrec.leafblk = leafblkno;
2260 [ + + ]: 148 : if (topparent != leafblkno)
2261 : 20 : xlrec.topparent = topparent;
2262 : : else
2263 : 128 : xlrec.topparent = InvalidBlockNumber;
2264 : :
2265 : 148 : XLogBeginInsert();
2266 : 148 : XLogRegisterBuffer(0, leafbuf, REGBUF_WILL_INIT);
2267 : 148 : XLogRegisterBuffer(1, subtreeparent, REGBUF_STANDARD);
2268 : :
2269 : 148 : page = BufferGetPage(leafbuf);
2270 : 148 : opaque = BTPageGetOpaque(page);
2271 : 148 : xlrec.leftblk = opaque->btpo_prev;
2272 : 148 : xlrec.rightblk = opaque->btpo_next;
2273 : :
2274 : 148 : XLogRegisterData(&xlrec, SizeOfBtreeMarkPageHalfDead);
2275 : :
2276 : 148 : recptr = XLogInsert(RM_BTREE_ID, XLOG_BTREE_MARK_PAGE_HALFDEAD);
2277 : :
2278 : 148 : page = BufferGetPage(subtreeparent);
2279 : 148 : PageSetLSN(page, recptr);
2280 : 148 : page = BufferGetPage(leafbuf);
2281 : 148 : PageSetLSN(page, recptr);
2282 : 148 : }
2283 : :
2284 [ + - ]: 148 : END_CRIT_SECTION();
2285 : :
2286 : 148 : _bt_relbuf(rel, subtreeparent);
2287 : 148 : return true;
2288 : 151 : }
2289 : :
2290 : : /*
2291 : : * Second stage of page deletion.
2292 : : *
2293 : : * Unlinks a single page (in the subtree undergoing deletion) from its
2294 : : * siblings. Also marks the page deleted.
2295 : : *
2296 : : * To get rid of the whole subtree, including the leaf page itself, call here
2297 : : * until the leaf page is deleted. The original "top parent" established in
2298 : : * the first stage of deletion is deleted in the first call here, while the
2299 : : * leaf page is deleted in the last call here. Note that the leaf page itself
2300 : : * is often the initial top parent page.
2301 : : *
2302 : : * Returns 'false' if the page could not be unlinked (shouldn't happen). If
2303 : : * the right sibling of the current target page is empty, *rightsib_empty is
2304 : : * set to true, allowing caller to delete the target's right sibling page in
2305 : : * passing. Note that *rightsib_empty is only actually used by caller when
2306 : : * target page is leafbuf, following last call here for leafbuf/the subtree
2307 : : * containing leafbuf. (We always set *rightsib_empty for caller, just to be
2308 : : * consistent.)
2309 : : *
2310 : : * Must hold pin and lock on leafbuf at entry (read or write doesn't matter).
2311 : : * On success exit, we'll be holding pin and write lock. On failure exit,
2312 : : * we'll release both pin and lock before returning (we define it that way
2313 : : * to avoid having to reacquire a lock we already released).
2314 : : */
2315 : : static bool
2316 : 194 : _bt_unlink_halfdead_page(Relation rel, Buffer leafbuf, BlockNumber scanblkno,
2317 : : bool *rightsib_empty, BTVacState *vstate)
2318 : : {
2319 : 194 : BlockNumber leafblkno = BufferGetBlockNumber(leafbuf);
2320 : 194 : IndexBulkDeleteResult *stats = vstate->stats;
2321 : 194 : BlockNumber leafleftsib;
2322 : 194 : BlockNumber leafrightsib;
2323 : 194 : BlockNumber target;
2324 : 194 : BlockNumber leftsib;
2325 : 194 : BlockNumber rightsib;
2326 : 194 : Buffer lbuf = InvalidBuffer;
2327 : 194 : Buffer buf;
2328 : 194 : Buffer rbuf;
2329 : 194 : Buffer metabuf = InvalidBuffer;
2330 : 194 : Page metapg = NULL;
2331 : 194 : BTMetaPageData *metad = NULL;
2332 : 194 : ItemId itemid;
2333 : 194 : Page page;
2334 : 194 : BTPageOpaque opaque;
2335 : 194 : FullTransactionId safexid;
2336 : 194 : bool rightsib_is_rightmost;
2337 : 194 : uint32 targetlevel;
2338 : 194 : IndexTuple leafhikey;
2339 : 194 : BlockNumber leaftopparent;
2340 : :
2341 : 194 : page = BufferGetPage(leafbuf);
2342 : 194 : opaque = BTPageGetOpaque(page);
2343 : :
2344 [ + - ]: 194 : Assert(P_ISLEAF(opaque) && !P_ISDELETED(opaque) && P_ISHALFDEAD(opaque));
2345 : :
2346 : : /*
2347 : : * Remember some information about the leaf page.
2348 : : */
2349 : 194 : itemid = PageGetItemId(page, P_HIKEY);
2350 : 194 : leafhikey = (IndexTuple) PageGetItem(page, itemid);
2351 : 194 : target = BTreeTupleGetTopParent(leafhikey);
2352 : 194 : leafleftsib = opaque->btpo_prev;
2353 : 194 : leafrightsib = opaque->btpo_next;
2354 : :
2355 : 194 : _bt_unlockbuf(rel, leafbuf);
2356 : :
2357 : : INJECTION_POINT("nbtree-leave-page-half-dead", NULL);
2358 : :
2359 : : /*
2360 : : * Check here, as calling loops will have locks held, preventing
2361 : : * interrupts from being processed.
2362 : : */
2363 [ + - ]: 194 : CHECK_FOR_INTERRUPTS();
2364 : :
2365 : : /* Unlink the current top parent of the subtree */
2366 [ + + ]: 194 : if (!BlockNumberIsValid(target))
2367 : : {
2368 : : /* Target is leaf page (or leaf page is top parent, if you prefer) */
2369 : 148 : target = leafblkno;
2370 : :
2371 : 148 : buf = leafbuf;
2372 : 148 : leftsib = leafleftsib;
2373 : 148 : targetlevel = 0;
2374 : 148 : }
2375 : : else
2376 : : {
2377 : : /* Target is the internal page taken from leaf's top parent link */
2378 [ + - ]: 46 : Assert(target != leafblkno);
2379 : :
2380 : : /* Fetch the block number of the target's left sibling */
2381 : 46 : buf = _bt_getbuf(rel, target, BT_READ);
2382 : 46 : page = BufferGetPage(buf);
2383 : 46 : opaque = BTPageGetOpaque(page);
2384 : 46 : leftsib = opaque->btpo_prev;
2385 : 46 : targetlevel = opaque->btpo_level;
2386 [ + - ]: 46 : Assert(targetlevel > 0);
2387 : :
2388 : : /*
2389 : : * To avoid deadlocks, we'd better drop the target page lock before
2390 : : * going further.
2391 : : */
2392 : 46 : _bt_unlockbuf(rel, buf);
2393 : : }
2394 : :
2395 : : /*
2396 : : * We have to lock the pages we need to modify in the standard order:
2397 : : * moving right, then up. Else we will deadlock against other writers.
2398 : : *
2399 : : * So, first lock the leaf page, if it's not the target. Then find and
2400 : : * write-lock the current left sibling of the target page. The sibling
2401 : : * that was current a moment ago could have split, so we may have to move
2402 : : * right.
2403 : : */
2404 [ + + ]: 194 : if (target != leafblkno)
2405 : 46 : _bt_lockbuf(rel, leafbuf, BT_WRITE);
2406 [ + + ]: 194 : if (leftsib != P_NONE)
2407 : : {
2408 : 67 : lbuf = _bt_getbuf(rel, leftsib, BT_WRITE);
2409 : 67 : page = BufferGetPage(lbuf);
2410 : 67 : opaque = BTPageGetOpaque(page);
2411 [ - + - + ]: 67 : while (P_ISDELETED(opaque) || opaque->btpo_next != target)
2412 : : {
2413 : 0 : bool leftsibvalid = true;
2414 : :
2415 : : /*
2416 : : * Before we follow the link from the page that was the left
2417 : : * sibling mere moments ago, validate its right link. This
2418 : : * reduces the opportunities for loop to fail to ever make any
2419 : : * progress in the presence of index corruption.
2420 : : *
2421 : : * Note: we rely on the assumption that there can only be one
2422 : : * vacuum process running at a time (against the same index).
2423 : : */
2424 [ # # # # : 0 : if (P_RIGHTMOST(opaque) || P_ISDELETED(opaque) ||
# # ]
2425 : 0 : leftsib == opaque->btpo_next)
2426 : 0 : leftsibvalid = false;
2427 : :
2428 : 0 : leftsib = opaque->btpo_next;
2429 : 0 : _bt_relbuf(rel, lbuf);
2430 : :
2431 [ # # ]: 0 : if (!leftsibvalid)
2432 : : {
2433 : : /*
2434 : : * This is known to fail in the field; sibling link corruption
2435 : : * is relatively common. Press on with vacuuming rather than
2436 : : * just throwing an ERROR.
2437 : : */
2438 [ # # # # ]: 0 : ereport(LOG,
2439 : : (errcode(ERRCODE_INDEX_CORRUPTED),
2440 : : errmsg_internal("valid left sibling for deletion target could not be located: "
2441 : : "left sibling %u of target %u with leafblkno %u and scanblkno %u on level %u of index \"%s\"",
2442 : : leftsib, target, leafblkno, scanblkno,
2443 : : targetlevel, RelationGetRelationName(rel))));
2444 : :
2445 : : /* Must release all pins and locks on failure exit */
2446 : 0 : ReleaseBuffer(buf);
2447 [ # # ]: 0 : if (target != leafblkno)
2448 : 0 : _bt_relbuf(rel, leafbuf);
2449 : :
2450 : 0 : return false;
2451 : : }
2452 : :
2453 [ # # ]: 0 : CHECK_FOR_INTERRUPTS();
2454 : :
2455 : : /* step right one page */
2456 : 0 : lbuf = _bt_getbuf(rel, leftsib, BT_WRITE);
2457 : 0 : page = BufferGetPage(lbuf);
2458 : 0 : opaque = BTPageGetOpaque(page);
2459 [ # # ]: 0 : }
2460 : 67 : }
2461 : : else
2462 : 127 : lbuf = InvalidBuffer;
2463 : :
2464 : : /* Next write-lock the target page itself */
2465 : 194 : _bt_lockbuf(rel, buf, BT_WRITE);
2466 : 194 : page = BufferGetPage(buf);
2467 : 194 : opaque = BTPageGetOpaque(page);
2468 : :
2469 : : /*
2470 : : * Check page is still empty etc, else abandon deletion. This is just for
2471 : : * paranoia's sake; a half-dead page cannot resurrect because there can be
2472 : : * only one vacuum process running at a time.
2473 : : */
2474 [ + - ]: 194 : if (P_RIGHTMOST(opaque) || P_ISROOT(opaque) || P_ISDELETED(opaque))
2475 [ # # # # ]: 0 : elog(ERROR, "target page changed status unexpectedly in block %u of index \"%s\"",
2476 : : target, RelationGetRelationName(rel));
2477 : :
2478 [ + - ]: 194 : if (opaque->btpo_prev != leftsib)
2479 [ # # # # ]: 0 : ereport(ERROR,
2480 : : (errcode(ERRCODE_INDEX_CORRUPTED),
2481 : : errmsg_internal("target page left link unexpectedly changed from %u to %u in block %u of index \"%s\"",
2482 : : leftsib, opaque->btpo_prev, target,
2483 : : RelationGetRelationName(rel))));
2484 : :
2485 [ + + ]: 194 : if (target == leafblkno)
2486 : : {
2487 [ + - ]: 148 : if (P_FIRSTDATAKEY(opaque) <= PageGetMaxOffsetNumber(page) ||
2488 : 148 : !P_ISLEAF(opaque) || !P_ISHALFDEAD(opaque))
2489 [ # # # # ]: 0 : elog(ERROR, "target leaf page changed status unexpectedly in block %u of index \"%s\"",
2490 : : target, RelationGetRelationName(rel));
2491 : :
2492 : : /* Leaf page is also target page: don't set leaftopparent */
2493 : 148 : leaftopparent = InvalidBlockNumber;
2494 : 148 : }
2495 : : else
2496 : : {
2497 : 46 : IndexTuple finaldataitem;
2498 : :
2499 [ + - ]: 46 : if (P_FIRSTDATAKEY(opaque) != PageGetMaxOffsetNumber(page) ||
2500 : 46 : P_ISLEAF(opaque))
2501 [ # # # # ]: 0 : elog(ERROR, "target internal page on level %u changed status unexpectedly in block %u of index \"%s\"",
2502 : : targetlevel, target, RelationGetRelationName(rel));
2503 : :
2504 : : /* Target is internal: set leaftopparent for next call here... */
2505 : 46 : itemid = PageGetItemId(page, P_FIRSTDATAKEY(opaque));
2506 : 46 : finaldataitem = (IndexTuple) PageGetItem(page, itemid);
2507 : 46 : leaftopparent = BTreeTupleGetDownLink(finaldataitem);
2508 : : /* ...except when it would be a redundant pointer-to-self */
2509 [ + + ]: 46 : if (leaftopparent == leafblkno)
2510 : 20 : leaftopparent = InvalidBlockNumber;
2511 : 46 : }
2512 : :
2513 : : /* No leaftopparent for level 0 (leaf page) or level 1 target */
2514 [ + + + - ]: 194 : Assert(!BlockNumberIsValid(leaftopparent) || targetlevel > 1);
2515 : :
2516 : : /*
2517 : : * And next write-lock the (current) right sibling.
2518 : : */
2519 : 194 : rightsib = opaque->btpo_next;
2520 : 194 : rbuf = _bt_getbuf(rel, rightsib, BT_WRITE);
2521 : 194 : page = BufferGetPage(rbuf);
2522 : 194 : opaque = BTPageGetOpaque(page);
2523 : :
2524 : : /*
2525 : : * Validate target's right sibling page. Its left link must point back to
2526 : : * the target page.
2527 : : */
2528 [ - + ]: 194 : if (opaque->btpo_prev != target)
2529 : : {
2530 : : /*
2531 : : * This is known to fail in the field; sibling link corruption is
2532 : : * relatively common. Press on with vacuuming rather than just
2533 : : * throwing an ERROR (same approach used for left-sibling's-right-link
2534 : : * validation check a moment ago).
2535 : : */
2536 [ # # # # ]: 0 : ereport(LOG,
2537 : : (errcode(ERRCODE_INDEX_CORRUPTED),
2538 : : errmsg_internal("right sibling's left-link doesn't match: "
2539 : : "right sibling %u of target %u with leafblkno %u "
2540 : : "and scanblkno %u spuriously links to non-target %u "
2541 : : "on level %u of index \"%s\"",
2542 : : rightsib, target, leafblkno,
2543 : : scanblkno, opaque->btpo_prev,
2544 : : targetlevel, RelationGetRelationName(rel))));
2545 : :
2546 : : /* Must release all pins and locks on failure exit */
2547 [ # # ]: 0 : if (BufferIsValid(lbuf))
2548 : 0 : _bt_relbuf(rel, lbuf);
2549 : 0 : _bt_relbuf(rel, rbuf);
2550 : 0 : _bt_relbuf(rel, buf);
2551 [ # # ]: 0 : if (target != leafblkno)
2552 : 0 : _bt_relbuf(rel, leafbuf);
2553 : :
2554 : 0 : return false;
2555 : : }
2556 : :
2557 : 194 : rightsib_is_rightmost = P_RIGHTMOST(opaque);
2558 : 194 : *rightsib_empty = (P_FIRSTDATAKEY(opaque) > PageGetMaxOffsetNumber(page));
2559 : :
2560 : : /*
2561 : : * If we are deleting the next-to-last page on the target's level, then
2562 : : * the rightsib is a candidate to become the new fast root. (In theory, it
2563 : : * might be possible to push the fast root even further down, but the odds
2564 : : * of doing so are slim, and the locking considerations daunting.)
2565 : : *
2566 : : * We can safely acquire a lock on the metapage here --- see comments for
2567 : : * _bt_newlevel().
2568 : : */
2569 [ + + + + ]: 194 : if (leftsib == P_NONE && rightsib_is_rightmost)
2570 : : {
2571 : 8 : page = BufferGetPage(rbuf);
2572 : 8 : opaque = BTPageGetOpaque(page);
2573 [ + - ]: 8 : if (P_RIGHTMOST(opaque))
2574 : : {
2575 : : /* rightsib will be the only one left on the level */
2576 : 8 : metabuf = _bt_getbuf(rel, BTREE_METAPAGE, BT_WRITE);
2577 : 8 : metapg = BufferGetPage(metabuf);
2578 : 8 : metad = BTPageGetMeta(metapg);
2579 : :
2580 : : /*
2581 : : * The expected case here is btm_fastlevel == targetlevel+1; if
2582 : : * the fastlevel is <= targetlevel, something is wrong, and we
2583 : : * choose to overwrite it to fix it.
2584 : : */
2585 [ + - ]: 8 : if (metad->btm_fastlevel > targetlevel + 1)
2586 : : {
2587 : : /* no update wanted */
2588 : 0 : _bt_relbuf(rel, metabuf);
2589 : 0 : metabuf = InvalidBuffer;
2590 : 0 : }
2591 : 8 : }
2592 : 8 : }
2593 : :
2594 : : /*
2595 : : * Here we begin doing the deletion.
2596 : : */
2597 : :
2598 : : /* No ereport(ERROR) until changes are logged */
2599 : 194 : START_CRIT_SECTION();
2600 : :
2601 : : /*
2602 : : * Update siblings' side-links. Note the target page's side-links will
2603 : : * continue to point to the siblings. Asserts here are just rechecking
2604 : : * things we already verified above.
2605 : : */
2606 [ + + ]: 194 : if (BufferIsValid(lbuf))
2607 : : {
2608 : 67 : page = BufferGetPage(lbuf);
2609 : 67 : opaque = BTPageGetOpaque(page);
2610 [ + - ]: 67 : Assert(opaque->btpo_next == target);
2611 : 67 : opaque->btpo_next = rightsib;
2612 : 67 : }
2613 : 194 : page = BufferGetPage(rbuf);
2614 : 194 : opaque = BTPageGetOpaque(page);
2615 [ + - ]: 194 : Assert(opaque->btpo_prev == target);
2616 : 194 : opaque->btpo_prev = leftsib;
2617 : :
2618 : : /*
2619 : : * If we deleted a parent of the targeted leaf page, instead of the leaf
2620 : : * itself, update the leaf to point to the next remaining child in the
2621 : : * subtree.
2622 : : *
2623 : : * Note: We rely on the fact that a buffer pin on the leaf page has been
2624 : : * held since leafhikey was initialized. This is safe, though only
2625 : : * because the page was already half-dead at that point. The leaf page
2626 : : * cannot have been modified by any other backend during the period when
2627 : : * no lock was held.
2628 : : */
2629 [ + + ]: 194 : if (target != leafblkno)
2630 : 46 : BTreeTupleSetTopParent(leafhikey, leaftopparent);
2631 : :
2632 : : /*
2633 : : * Mark the page itself deleted. It can be recycled when all current
2634 : : * transactions are gone. Storing GetTopTransactionId() would work, but
2635 : : * we're in VACUUM and would not otherwise have an XID. Having already
2636 : : * updated links to the target, ReadNextFullTransactionId() suffices as an
2637 : : * upper bound. Any scan having retained a now-stale link is advertising
2638 : : * in its PGPROC an xmin less than or equal to the value we read here. It
2639 : : * will continue to do so, holding back the xmin horizon, for the duration
2640 : : * of that scan.
2641 : : */
2642 : 194 : page = BufferGetPage(buf);
2643 : 194 : opaque = BTPageGetOpaque(page);
2644 [ + + + - ]: 194 : Assert(P_ISHALFDEAD(opaque) || !P_ISLEAF(opaque));
2645 : :
2646 : : /*
2647 : : * Store upper bound XID that's used to determine when deleted page is no
2648 : : * longer needed as a tombstone
2649 : : */
2650 : 194 : safexid = ReadNextFullTransactionId();
2651 : 194 : BTPageSetDeleted(page, safexid);
2652 : 194 : opaque->btpo_cycleid = 0;
2653 : :
2654 : : /* And update the metapage, if needed */
2655 [ + + ]: 194 : if (BufferIsValid(metabuf))
2656 : : {
2657 : : /* upgrade metapage if needed */
2658 [ + - ]: 8 : if (metad->btm_version < BTREE_NOVAC_VERSION)
2659 : 0 : _bt_upgrademetapage(metapg);
2660 : 8 : metad->btm_fastroot = rightsib;
2661 : 8 : metad->btm_fastlevel = targetlevel;
2662 : 8 : MarkBufferDirty(metabuf);
2663 : 8 : }
2664 : :
2665 : : /* Must mark buffers dirty before XLogInsert */
2666 : 194 : MarkBufferDirty(rbuf);
2667 : 194 : MarkBufferDirty(buf);
2668 [ + + ]: 194 : if (BufferIsValid(lbuf))
2669 : 67 : MarkBufferDirty(lbuf);
2670 [ + + ]: 194 : if (target != leafblkno)
2671 : 46 : MarkBufferDirty(leafbuf);
2672 : :
2673 : : /* XLOG stuff */
2674 [ + - + - : 194 : if (RelationNeedsWAL(rel))
+ - - + ]
2675 : : {
2676 : 194 : xl_btree_unlink_page xlrec;
2677 : 194 : xl_btree_metadata xlmeta;
2678 : 194 : uint8 xlinfo;
2679 : 194 : XLogRecPtr recptr;
2680 : :
2681 : 194 : XLogBeginInsert();
2682 : :
2683 : 194 : XLogRegisterBuffer(0, buf, REGBUF_WILL_INIT);
2684 [ + + ]: 194 : if (BufferIsValid(lbuf))
2685 : 67 : XLogRegisterBuffer(1, lbuf, REGBUF_STANDARD);
2686 : 194 : XLogRegisterBuffer(2, rbuf, REGBUF_STANDARD);
2687 [ + + ]: 194 : if (target != leafblkno)
2688 : 46 : XLogRegisterBuffer(3, leafbuf, REGBUF_WILL_INIT);
2689 : :
2690 : : /* information stored on the target/to-be-unlinked block */
2691 : 194 : xlrec.leftsib = leftsib;
2692 : 194 : xlrec.rightsib = rightsib;
2693 : 194 : xlrec.level = targetlevel;
2694 : 194 : xlrec.safexid = safexid;
2695 : :
2696 : : /* information needed to recreate the leaf block (if not the target) */
2697 : 194 : xlrec.leafleftsib = leafleftsib;
2698 : 194 : xlrec.leafrightsib = leafrightsib;
2699 : 194 : xlrec.leaftopparent = leaftopparent;
2700 : :
2701 : 194 : XLogRegisterData(&xlrec, SizeOfBtreeUnlinkPage);
2702 : :
2703 [ + + ]: 194 : if (BufferIsValid(metabuf))
2704 : : {
2705 : 8 : XLogRegisterBuffer(4, metabuf, REGBUF_WILL_INIT | REGBUF_STANDARD);
2706 : :
2707 [ + - ]: 8 : Assert(metad->btm_version >= BTREE_NOVAC_VERSION);
2708 : 8 : xlmeta.version = metad->btm_version;
2709 : 8 : xlmeta.root = metad->btm_root;
2710 : 8 : xlmeta.level = metad->btm_level;
2711 : 8 : xlmeta.fastroot = metad->btm_fastroot;
2712 : 8 : xlmeta.fastlevel = metad->btm_fastlevel;
2713 : 8 : xlmeta.last_cleanup_num_delpages = metad->btm_last_cleanup_num_delpages;
2714 : 8 : xlmeta.allequalimage = metad->btm_allequalimage;
2715 : :
2716 : 8 : XLogRegisterBufData(4, &xlmeta, sizeof(xl_btree_metadata));
2717 : 8 : xlinfo = XLOG_BTREE_UNLINK_PAGE_META;
2718 : 8 : }
2719 : : else
2720 : 186 : xlinfo = XLOG_BTREE_UNLINK_PAGE;
2721 : :
2722 : 194 : recptr = XLogInsert(RM_BTREE_ID, xlinfo);
2723 : :
2724 [ + + ]: 194 : if (BufferIsValid(metabuf))
2725 : : {
2726 : 8 : PageSetLSN(metapg, recptr);
2727 : 8 : }
2728 : 194 : page = BufferGetPage(rbuf);
2729 : 194 : PageSetLSN(page, recptr);
2730 : 194 : page = BufferGetPage(buf);
2731 : 194 : PageSetLSN(page, recptr);
2732 [ + + ]: 194 : if (BufferIsValid(lbuf))
2733 : : {
2734 : 67 : page = BufferGetPage(lbuf);
2735 : 67 : PageSetLSN(page, recptr);
2736 : 67 : }
2737 [ + + ]: 194 : if (target != leafblkno)
2738 : : {
2739 : 46 : page = BufferGetPage(leafbuf);
2740 : 46 : PageSetLSN(page, recptr);
2741 : 46 : }
2742 : 194 : }
2743 : :
2744 [ + - ]: 194 : END_CRIT_SECTION();
2745 : :
2746 : : /* release metapage */
2747 [ + + ]: 194 : if (BufferIsValid(metabuf))
2748 : 8 : _bt_relbuf(rel, metabuf);
2749 : :
2750 : : /* release siblings */
2751 [ + + ]: 194 : if (BufferIsValid(lbuf))
2752 : 67 : _bt_relbuf(rel, lbuf);
2753 : 194 : _bt_relbuf(rel, rbuf);
2754 : :
2755 : : /* If the target is not leafbuf, we're done with it now -- release it */
2756 [ + + ]: 194 : if (target != leafblkno)
2757 : 46 : _bt_relbuf(rel, buf);
2758 : :
2759 : : /*
2760 : : * Maintain pages_newly_deleted, which is simply the number of pages
2761 : : * deleted by the ongoing VACUUM operation.
2762 : : *
2763 : : * Maintain pages_deleted in a way that takes into account how
2764 : : * btvacuumpage() will count deleted pages that have yet to become
2765 : : * scanblkno -- only count page when it's not going to get that treatment
2766 : : * later on.
2767 : : */
2768 : 194 : stats->pages_newly_deleted++;
2769 [ + + ]: 194 : if (target <= scanblkno)
2770 : 155 : stats->pages_deleted++;
2771 : :
2772 : : /*
2773 : : * Remember information about the target page (now a newly deleted page)
2774 : : * in dedicated vstate space for later. The page will be considered as a
2775 : : * candidate to place in the FSM at the end of the current btvacuumscan()
2776 : : * call.
2777 : : */
2778 : 194 : _bt_pendingfsm_add(vstate, target, safexid);
2779 : :
2780 : : /* Success - hold on to lock on leafbuf (might also have been target) */
2781 : 194 : return true;
2782 : 194 : }
2783 : :
2784 : : /*
2785 : : * Establish how tall the to-be-deleted subtree will be during the first stage
2786 : : * of page deletion.
2787 : : *
2788 : : * Caller's child argument is the block number of the page caller wants to
2789 : : * delete (this is leafbuf's block number, except when we're called
2790 : : * recursively). stack is a search stack leading to it. Note that we will
2791 : : * update the stack entry(s) to reflect current downlink positions --- this is
2792 : : * similar to the corresponding point in page split handling.
2793 : : *
2794 : : * If "first stage" caller cannot go ahead with deleting _any_ pages, returns
2795 : : * false. Returns true on success, in which case caller can use certain
2796 : : * details established here to perform the first stage of deletion. This
2797 : : * function is the last point at which page deletion may be deemed unsafe
2798 : : * (barring index corruption, or unexpected concurrent page deletions).
2799 : : *
2800 : : * We write lock the parent of the root of the to-be-deleted subtree for
2801 : : * caller on success (i.e. we leave our lock on the *subtreeparent buffer for
2802 : : * caller). Caller will have to remove a downlink from *subtreeparent. We
2803 : : * also set a *subtreeparent offset number in *poffset, to indicate the
2804 : : * location of the pivot tuple that contains the relevant downlink.
2805 : : *
2806 : : * The root of the to-be-deleted subtree is called the "top parent". Note
2807 : : * that the leafbuf page is often the final "top parent" page (you can think
2808 : : * of the leafbuf page as a degenerate single page subtree when that happens).
2809 : : * Caller should initialize *topparent to the target leafbuf page block number
2810 : : * (while *topparentrightsib should be set to leafbuf's right sibling block
2811 : : * number). We will update *topparent (and *topparentrightsib) for caller
2812 : : * here, though only when it turns out that caller will delete at least one
2813 : : * internal page (i.e. only when caller needs to store a valid link to the top
2814 : : * parent block in the leafbuf page using BTreeTupleSetTopParent()).
2815 : : */
2816 : : static bool
2817 : 204 : _bt_lock_subtree_parent(Relation rel, Relation heaprel, BlockNumber child,
2818 : : BTStack stack, Buffer *subtreeparent,
2819 : : OffsetNumber *poffset, BlockNumber *topparent,
2820 : : BlockNumber *topparentrightsib)
2821 : : {
2822 : 204 : BlockNumber parent,
2823 : : leftsibparent;
2824 : 204 : OffsetNumber parentoffset,
2825 : : maxoff;
2826 : 204 : Buffer pbuf;
2827 : 204 : Page page;
2828 : 204 : BTPageOpaque opaque;
2829 : :
2830 : : /*
2831 : : * Locate the pivot tuple whose downlink points to "child". Write lock
2832 : : * the parent page itself.
2833 : : */
2834 : 204 : pbuf = _bt_getstackbuf(rel, heaprel, stack, child);
2835 [ + - ]: 204 : if (pbuf == InvalidBuffer)
2836 : : {
2837 : : /*
2838 : : * Failed to "re-find" a pivot tuple whose downlink matched our child
2839 : : * block number on the parent level -- the index must be corrupt.
2840 : : * Don't even try to delete the leafbuf subtree. Just report the
2841 : : * issue and press on with vacuuming the index.
2842 : : *
2843 : : * Note: _bt_getstackbuf() recovers from concurrent page splits that
2844 : : * take place on the parent level. Its approach is a near-exhaustive
2845 : : * linear search. This also gives it a surprisingly good chance of
2846 : : * recovering in the event of a buggy or inconsistent opclass. But we
2847 : : * don't rely on that here.
2848 : : */
2849 [ # # # # ]: 0 : ereport(LOG,
2850 : : (errcode(ERRCODE_INDEX_CORRUPTED),
2851 : : errmsg_internal("failed to re-find parent key in index \"%s\" for deletion target page %u",
2852 : : RelationGetRelationName(rel), child)));
2853 : 0 : Assert(false);
2854 : 0 : return false;
2855 : : }
2856 : :
2857 : 204 : parent = stack->bts_blkno;
2858 : 204 : parentoffset = stack->bts_offset;
2859 : :
2860 : 204 : page = BufferGetPage(pbuf);
2861 : 204 : opaque = BTPageGetOpaque(page);
2862 : 204 : maxoff = PageGetMaxOffsetNumber(page);
2863 : 204 : leftsibparent = opaque->btpo_prev;
2864 : :
2865 : : /*
2866 : : * _bt_getstackbuf() completes page splits on returned parent buffer when
2867 : : * required.
2868 : : *
2869 : : * In general it's a bad idea for VACUUM to use up more disk space, which
2870 : : * is why page deletion does not finish incomplete page splits most of the
2871 : : * time. We allow this limited exception because the risk is much lower,
2872 : : * and the potential downside of not proceeding is much higher: A single
2873 : : * internal page with the INCOMPLETE_SPLIT flag set might otherwise
2874 : : * prevent us from deleting hundreds of empty leaf pages from one level
2875 : : * down.
2876 : : */
2877 [ + - ]: 204 : Assert(!P_INCOMPLETE_SPLIT(opaque));
2878 : :
2879 [ + + ]: 204 : if (parentoffset < maxoff)
2880 : : {
2881 : : /*
2882 : : * Child is not the rightmost child in parent, so it's safe to delete
2883 : : * the subtree whose root/topparent is child page
2884 : : */
2885 : 148 : *subtreeparent = pbuf;
2886 : 148 : *poffset = parentoffset;
2887 : 148 : return true;
2888 : : }
2889 : :
2890 : : /*
2891 : : * Child is the rightmost child of parent.
2892 : : *
2893 : : * Since it's the rightmost child of parent, deleting the child (or
2894 : : * deleting the subtree whose root/topparent is the child page) is only
2895 : : * safe when it's also possible to delete the parent.
2896 : : */
2897 [ + - ]: 56 : Assert(parentoffset == maxoff);
2898 [ + + - + ]: 56 : if (parentoffset != P_FIRSTDATAKEY(opaque) || P_RIGHTMOST(opaque))
2899 : : {
2900 : : /*
2901 : : * Child isn't parent's only child, or parent is rightmost on its
2902 : : * entire level. Definitely cannot delete any pages.
2903 : : */
2904 : 3 : _bt_relbuf(rel, pbuf);
2905 : 3 : return false;
2906 : : }
2907 : :
2908 : : /*
2909 : : * Now make sure that the parent deletion is itself safe by examining the
2910 : : * child's grandparent page. Recurse, passing the parent page as the
2911 : : * child page (child's grandparent is the parent on the next level up). If
2912 : : * parent deletion is unsafe, then child deletion must also be unsafe (in
2913 : : * which case caller cannot delete any pages at all).
2914 : : */
2915 : 53 : *topparent = parent;
2916 : 53 : *topparentrightsib = opaque->btpo_next;
2917 : :
2918 : : /*
2919 : : * Release lock on parent before recursing.
2920 : : *
2921 : : * It's OK to release page locks on parent before recursive call locks
2922 : : * grandparent. An internal page can only acquire an entry if the child
2923 : : * is split, but that cannot happen as long as we still hold a lock on the
2924 : : * leafbuf page.
2925 : : */
2926 : 53 : _bt_relbuf(rel, pbuf);
2927 : :
2928 : : /*
2929 : : * Before recursing, check that the left sibling of parent (if any) is not
2930 : : * marked with INCOMPLETE_SPLIT flag first (must do so after we drop the
2931 : : * parent lock).
2932 : : *
2933 : : * Note: We deliberately avoid completing incomplete splits here.
2934 : : */
2935 [ - + ]: 53 : if (_bt_leftsib_splitflag(rel, leftsibparent, parent))
2936 : 0 : return false;
2937 : :
2938 : : /* Recurse to examine child page's grandparent page */
2939 : 106 : return _bt_lock_subtree_parent(rel, heaprel, parent, stack->bts_parent,
2940 : 53 : subtreeparent, poffset,
2941 : 53 : topparent, topparentrightsib);
2942 : 204 : }
2943 : :
2944 : : /*
2945 : : * Initialize local memory state used by VACUUM for _bt_pendingfsm_finalize
2946 : : * optimization.
2947 : : *
2948 : : * Called at the start of a btvacuumscan(). Caller's cleanuponly argument
2949 : : * indicates if ongoing VACUUM has not (and will not) call btbulkdelete().
2950 : : *
2951 : : * We expect to allocate memory inside VACUUM's top-level memory context here.
2952 : : * The working buffer is subject to a limit based on work_mem. Our strategy
2953 : : * when the array can no longer grow within the bounds of that limit is to
2954 : : * stop saving additional newly deleted pages, while proceeding as usual with
2955 : : * the pages that we can fit.
2956 : : */
2957 : : void
2958 : 170 : _bt_pendingfsm_init(Relation rel, BTVacState *vstate, bool cleanuponly)
2959 : : {
2960 : 170 : Size maxbufsize;
2961 : :
2962 : : /*
2963 : : * Don't bother with optimization in cleanup-only case -- we don't expect
2964 : : * any newly deleted pages. Besides, cleanup-only calls to btvacuumscan()
2965 : : * can only take place because this optimization didn't work out during
2966 : : * the last VACUUM.
2967 : : */
2968 [ + + ]: 170 : if (cleanuponly)
2969 : 1 : return;
2970 : :
2971 : : /*
2972 : : * Cap maximum size of array so that we always respect work_mem. Avoid
2973 : : * int overflow here.
2974 : : */
2975 : 169 : vstate->bufsize = 256;
2976 : 169 : maxbufsize = (work_mem * (Size) 1024) / sizeof(BTPendingFSM);
2977 [ + - ]: 169 : maxbufsize = Min(maxbufsize, MaxAllocSize / sizeof(BTPendingFSM));
2978 : : /* BTVacState.maxbufsize has type int */
2979 [ + - ]: 169 : maxbufsize = Min(maxbufsize, INT_MAX);
2980 : : /* Stay sane with small work_mem */
2981 [ + - ]: 169 : maxbufsize = Max(maxbufsize, vstate->bufsize);
2982 : 169 : vstate->maxbufsize = (int) maxbufsize;
2983 : :
2984 : : /* Allocate buffer, indicate that there are currently 0 pending pages */
2985 : 169 : vstate->pendingpages = palloc_array(BTPendingFSM, vstate->bufsize);
2986 : 169 : vstate->npendingpages = 0;
2987 [ - + ]: 170 : }
2988 : :
2989 : : /*
2990 : : * Place any newly deleted pages (i.e. pages that _bt_pagedel() deleted during
2991 : : * the ongoing VACUUM operation) into the free space map -- though only when
2992 : : * it is actually safe to do so by now.
2993 : : *
2994 : : * Called at the end of a btvacuumscan(), just before free space map vacuuming
2995 : : * takes place.
2996 : : *
2997 : : * Frees memory allocated by _bt_pendingfsm_init(), if any.
2998 : : */
2999 : : void
3000 : 170 : _bt_pendingfsm_finalize(Relation rel, BTVacState *vstate)
3001 : : {
3002 : 170 : IndexBulkDeleteResult *stats = vstate->stats;
3003 : 170 : Relation heaprel = vstate->info->heaprel;
3004 : :
3005 [ + - ]: 170 : Assert(stats->pages_newly_deleted >= vstate->npendingpages);
3006 [ + - ]: 170 : Assert(heaprel != NULL);
3007 : :
3008 [ + + ]: 170 : if (vstate->npendingpages == 0)
3009 : : {
3010 : : /* Just free memory when nothing to do */
3011 [ + + ]: 156 : if (vstate->pendingpages)
3012 : 155 : pfree(vstate->pendingpages);
3013 : :
3014 : 156 : return;
3015 : : }
3016 : :
3017 : : #ifdef DEBUG_BTREE_PENDING_FSM
3018 : :
3019 : : /*
3020 : : * Debugging aid: Sleep for 5 seconds to greatly increase the chances of
3021 : : * placing pending pages in the FSM. Note that the optimization will
3022 : : * never be effective without some other backend concurrently consuming an
3023 : : * XID.
3024 : : */
3025 : : pg_usleep(5000000L);
3026 : : #endif
3027 : :
3028 : : /*
3029 : : * Recompute VACUUM XID boundaries.
3030 : : *
3031 : : * We don't actually care about the oldest non-removable XID. Computing
3032 : : * the oldest such XID has a useful side-effect that we rely on: it
3033 : : * forcibly updates the XID horizon state for this backend. This step is
3034 : : * essential; GlobalVisCheckRemovableFullXid() will not reliably recognize
3035 : : * that it is now safe to recycle newly deleted pages without this step.
3036 : : */
3037 : 14 : GetOldestNonRemovableTransactionId(heaprel);
3038 : :
3039 [ + - ]: 28 : for (int i = 0; i < vstate->npendingpages; i++)
3040 : : {
3041 : 14 : BlockNumber target = vstate->pendingpages[i].target;
3042 : 14 : FullTransactionId safexid = vstate->pendingpages[i].safexid;
3043 : :
3044 : : /*
3045 : : * Do the equivalent of checking BTPageIsRecyclable(), but without
3046 : : * accessing the page again a second time.
3047 : : *
3048 : : * Give up on finding the first non-recyclable page -- all later pages
3049 : : * must be non-recyclable too, since _bt_pendingfsm_add() adds pages
3050 : : * to the array in safexid order.
3051 : : */
3052 [ - + ]: 14 : if (!GlobalVisCheckRemovableFullXid(heaprel, safexid))
3053 : 14 : break;
3054 : :
3055 : 0 : RecordFreeIndexPage(rel, target);
3056 : 0 : stats->pages_free++;
3057 [ + - ]: 14 : }
3058 : :
3059 : 14 : pfree(vstate->pendingpages);
3060 [ - + ]: 170 : }
3061 : :
3062 : : /*
3063 : : * Maintain array of pages that were deleted during current btvacuumscan()
3064 : : * call, for use in _bt_pendingfsm_finalize()
3065 : : */
3066 : : static void
3067 : 194 : _bt_pendingfsm_add(BTVacState *vstate,
3068 : : BlockNumber target,
3069 : : FullTransactionId safexid)
3070 : : {
3071 [ + - ]: 194 : Assert(vstate->npendingpages <= vstate->bufsize);
3072 [ + - ]: 194 : Assert(vstate->bufsize <= vstate->maxbufsize);
3073 : :
3074 : : #ifdef USE_ASSERT_CHECKING
3075 : :
3076 : : /*
3077 : : * Verify an assumption made by _bt_pendingfsm_finalize(): pages from the
3078 : : * array will always be in safexid order (since that is the order that we
3079 : : * save them in here)
3080 : : */
3081 [ + + ]: 194 : if (vstate->npendingpages > 0)
3082 : : {
3083 : 180 : FullTransactionId lastsafexid =
3084 : 180 : vstate->pendingpages[vstate->npendingpages - 1].safexid;
3085 : :
3086 [ + - ]: 180 : Assert(FullTransactionIdFollowsOrEquals(safexid, lastsafexid));
3087 : 180 : }
3088 : : #endif
3089 : :
3090 : : /*
3091 : : * If temp buffer reaches maxbufsize/work_mem capacity then we discard
3092 : : * information about this page.
3093 : : *
3094 : : * Note that this also covers the case where we opted to not use the
3095 : : * optimization in _bt_pendingfsm_init().
3096 : : */
3097 [ - + ]: 194 : if (vstate->npendingpages == vstate->maxbufsize)
3098 : 0 : return;
3099 : :
3100 : : /* Consider enlarging buffer */
3101 [ + - ]: 194 : if (vstate->npendingpages == vstate->bufsize)
3102 : : {
3103 : 0 : int newbufsize = vstate->bufsize * 2;
3104 : :
3105 : : /* Respect work_mem */
3106 [ # # ]: 0 : if (newbufsize > vstate->maxbufsize)
3107 : 0 : newbufsize = vstate->maxbufsize;
3108 : :
3109 : 0 : vstate->bufsize = newbufsize;
3110 : 0 : vstate->pendingpages =
3111 : 0 : repalloc(vstate->pendingpages,
3112 : 0 : sizeof(BTPendingFSM) * vstate->bufsize);
3113 : 0 : }
3114 : :
3115 : : /* Save metadata for newly deleted page */
3116 : 194 : vstate->pendingpages[vstate->npendingpages].target = target;
3117 : 194 : vstate->pendingpages[vstate->npendingpages].safexid = safexid;
3118 : 194 : vstate->npendingpages++;
3119 : 194 : }
|
