Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * storage.c
4 : * code to create and destroy physical storage for relations
5 : *
6 : * Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
7 : * Portions Copyright (c) 1994, Regents of the University of California
8 : *
9 : *
10 : * IDENTIFICATION
11 : * src/backend/catalog/storage.c
12 : *
13 : * NOTES
14 : * Some of this code used to be in storage/smgr/smgr.c, and the
15 : * function names still reflect that.
16 : *
17 : *-------------------------------------------------------------------------
18 : */
19 :
20 : #include "postgres.h"
21 :
22 : #include "access/visibilitymap.h"
23 : #include "access/xact.h"
24 : #include "access/xlog.h"
25 : #include "access/xloginsert.h"
26 : #include "access/xlogutils.h"
27 : #include "catalog/storage.h"
28 : #include "catalog/storage_xlog.h"
29 : #include "miscadmin.h"
30 : #include "storage/bulk_write.h"
31 : #include "storage/freespace.h"
32 : #include "storage/proc.h"
33 : #include "storage/smgr.h"
34 : #include "utils/hsearch.h"
35 : #include "utils/memutils.h"
36 : #include "utils/rel.h"
37 :
38 : /* GUC variables */
39 : int wal_skip_threshold = 2048; /* in kilobytes */
40 :
41 : /*
42 : * We keep a list of all relations (represented as RelFileLocator values)
43 : * that have been created or deleted in the current transaction. When
44 : * a relation is created, we create the physical file immediately, but
45 : * remember it so that we can delete the file again if the current
46 : * transaction is aborted. Conversely, a deletion request is NOT
47 : * executed immediately, but is just entered in the list. When and if
48 : * the transaction commits, we can delete the physical file.
49 : *
50 : * To handle subtransactions, every entry is marked with its transaction
51 : * nesting level. At subtransaction commit, we reassign the subtransaction's
52 : * entries to the parent nesting level. At subtransaction abort, we can
53 : * immediately execute the abort-time actions for all entries of the current
54 : * nesting level.
55 : *
56 : * NOTE: the list is kept in TopMemoryContext to be sure it won't disappear
57 : * unbetimes. It'd probably be OK to keep it in TopTransactionContext,
58 : * but I'm being paranoid.
59 : */
60 :
61 : typedef struct PendingRelDelete
62 : {
63 : RelFileLocator rlocator; /* relation that may need to be deleted */
64 : ProcNumber procNumber; /* INVALID_PROC_NUMBER if not a temp rel */
65 : bool atCommit; /* T=delete at commit; F=delete at abort */
66 : int nestLevel; /* xact nesting level of request */
67 : struct PendingRelDelete *next; /* linked-list link */
68 : } PendingRelDelete;
69 :
70 : typedef struct PendingRelSync
71 : {
72 : RelFileLocator rlocator;
73 : bool is_truncated; /* Has the file experienced truncation? */
74 : } PendingRelSync;
75 :
76 : static PendingRelDelete *pendingDeletes = NULL; /* head of linked list */
77 : static HTAB *pendingSyncHash = NULL;
78 :
79 :
80 : /*
81 : * AddPendingSync
82 : * Queue an at-commit fsync.
83 : */
84 : static void
85 69650 : AddPendingSync(const RelFileLocator *rlocator)
86 : {
87 : PendingRelSync *pending;
88 : bool found;
89 :
90 : /* create the hash if not yet */
91 69650 : if (!pendingSyncHash)
92 : {
93 : HASHCTL ctl;
94 :
95 11802 : ctl.keysize = sizeof(RelFileLocator);
96 11802 : ctl.entrysize = sizeof(PendingRelSync);
97 11802 : ctl.hcxt = TopTransactionContext;
98 11802 : pendingSyncHash = hash_create("pending sync hash", 16, &ctl,
99 : HASH_ELEM | HASH_BLOBS | HASH_CONTEXT);
100 : }
101 :
102 69650 : pending = hash_search(pendingSyncHash, rlocator, HASH_ENTER, &found);
103 : Assert(!found);
104 69650 : pending->is_truncated = false;
105 69650 : }
106 :
107 : /*
108 : * RelationCreateStorage
109 : * Create physical storage for a relation.
110 : *
111 : * Create the underlying disk file storage for the relation. This only
112 : * creates the main fork; additional forks are created lazily by the
113 : * modules that need them.
114 : *
115 : * This function is transactional. The creation is WAL-logged, and if the
116 : * transaction aborts later on, the storage will be destroyed. A caller
117 : * that does not want the storage to be destroyed in case of an abort may
118 : * pass register_delete = false.
119 : */
120 : SMgrRelation
121 209820 : RelationCreateStorage(RelFileLocator rlocator, char relpersistence,
122 : bool register_delete)
123 : {
124 : SMgrRelation srel;
125 : ProcNumber procNumber;
126 : bool needs_wal;
127 :
128 : Assert(!IsInParallelMode()); /* couldn't update pendingSyncHash */
129 :
130 209820 : switch (relpersistence)
131 : {
132 5998 : case RELPERSISTENCE_TEMP:
133 5998 : procNumber = ProcNumberForTempRelations();
134 5998 : needs_wal = false;
135 5998 : break;
136 530 : case RELPERSISTENCE_UNLOGGED:
137 530 : procNumber = INVALID_PROC_NUMBER;
138 530 : needs_wal = false;
139 530 : break;
140 203292 : case RELPERSISTENCE_PERMANENT:
141 203292 : procNumber = INVALID_PROC_NUMBER;
142 203292 : needs_wal = true;
143 203292 : break;
144 0 : default:
145 0 : elog(ERROR, "invalid relpersistence: %c", relpersistence);
146 : return NULL; /* placate compiler */
147 : }
148 :
149 209820 : srel = smgropen(rlocator, procNumber);
150 209820 : smgrcreate(srel, MAIN_FORKNUM, false);
151 :
152 209820 : if (needs_wal)
153 203292 : log_smgrcreate(&srel->smgr_rlocator.locator, MAIN_FORKNUM);
154 :
155 : /*
156 : * Add the relation to the list of stuff to delete at abort, if we are
157 : * asked to do so.
158 : */
159 209820 : if (register_delete)
160 : {
161 : PendingRelDelete *pending;
162 :
163 : pending = (PendingRelDelete *)
164 113020 : MemoryContextAlloc(TopMemoryContext, sizeof(PendingRelDelete));
165 113020 : pending->rlocator = rlocator;
166 113020 : pending->procNumber = procNumber;
167 113020 : pending->atCommit = false; /* delete if abort */
168 113020 : pending->nestLevel = GetCurrentTransactionNestLevel();
169 113020 : pending->next = pendingDeletes;
170 113020 : pendingDeletes = pending;
171 : }
172 :
173 209820 : if (relpersistence == RELPERSISTENCE_PERMANENT && !XLogIsNeeded())
174 : {
175 : Assert(procNumber == INVALID_PROC_NUMBER);
176 66054 : AddPendingSync(&rlocator);
177 : }
178 :
179 209820 : return srel;
180 : }
181 :
182 : /*
183 : * Perform XLogInsert of an XLOG_SMGR_CREATE record to WAL.
184 : */
185 : void
186 235806 : log_smgrcreate(const RelFileLocator *rlocator, ForkNumber forkNum)
187 : {
188 : xl_smgr_create xlrec;
189 :
190 : /*
191 : * Make an XLOG entry reporting the file creation.
192 : */
193 235806 : xlrec.rlocator = *rlocator;
194 235806 : xlrec.forkNum = forkNum;
195 :
196 235806 : XLogBeginInsert();
197 235806 : XLogRegisterData((char *) &xlrec, sizeof(xlrec));
198 235806 : XLogInsert(RM_SMGR_ID, XLOG_SMGR_CREATE | XLR_SPECIAL_REL_UPDATE);
199 235806 : }
200 :
201 : /*
202 : * RelationDropStorage
203 : * Schedule unlinking of physical storage at transaction commit.
204 : */
205 : void
206 69734 : RelationDropStorage(Relation rel)
207 : {
208 : PendingRelDelete *pending;
209 :
210 : /* Add the relation to the list of stuff to delete at commit */
211 : pending = (PendingRelDelete *)
212 69734 : MemoryContextAlloc(TopMemoryContext, sizeof(PendingRelDelete));
213 69734 : pending->rlocator = rel->rd_locator;
214 69734 : pending->procNumber = rel->rd_backend;
215 69734 : pending->atCommit = true; /* delete if commit */
216 69734 : pending->nestLevel = GetCurrentTransactionNestLevel();
217 69734 : pending->next = pendingDeletes;
218 69734 : pendingDeletes = pending;
219 :
220 : /*
221 : * NOTE: if the relation was created in this transaction, it will now be
222 : * present in the pending-delete list twice, once with atCommit true and
223 : * once with atCommit false. Hence, it will be physically deleted at end
224 : * of xact in either case (and the other entry will be ignored by
225 : * smgrDoPendingDeletes, so no error will occur). We could instead remove
226 : * the existing list entry and delete the physical file immediately, but
227 : * for now I'll keep the logic simple.
228 : */
229 :
230 69734 : RelationCloseSmgr(rel);
231 69734 : }
232 :
233 : /*
234 : * RelationPreserveStorage
235 : * Mark a relation as not to be deleted after all.
236 : *
237 : * We need this function because relation mapping changes are committed
238 : * separately from commit of the whole transaction, so it's still possible
239 : * for the transaction to abort after the mapping update is done.
240 : * When a new physical relation is installed in the map, it would be
241 : * scheduled for delete-on-abort, so we'd delete it, and be in trouble.
242 : * The relation mapper fixes this by telling us to not delete such relations
243 : * after all as part of its commit.
244 : *
245 : * We also use this to reuse an old build of an index during ALTER TABLE, this
246 : * time removing the delete-at-commit entry.
247 : *
248 : * No-op if the relation is not among those scheduled for deletion.
249 : */
250 : void
251 12522 : RelationPreserveStorage(RelFileLocator rlocator, bool atCommit)
252 : {
253 : PendingRelDelete *pending;
254 : PendingRelDelete *prev;
255 : PendingRelDelete *next;
256 :
257 12522 : prev = NULL;
258 74260 : for (pending = pendingDeletes; pending != NULL; pending = next)
259 : {
260 61738 : next = pending->next;
261 61738 : if (RelFileLocatorEquals(rlocator, pending->rlocator)
262 1122 : && pending->atCommit == atCommit)
263 : {
264 : /* unlink and delete list entry */
265 1116 : if (prev)
266 816 : prev->next = next;
267 : else
268 300 : pendingDeletes = next;
269 1116 : pfree(pending);
270 : /* prev does not change */
271 : }
272 : else
273 : {
274 : /* unrelated entry, don't touch it */
275 60622 : prev = pending;
276 : }
277 : }
278 12522 : }
279 :
280 : /*
281 : * RelationTruncate
282 : * Physically truncate a relation to the specified number of blocks.
283 : *
284 : * This includes getting rid of any buffers for the blocks that are to be
285 : * dropped.
286 : */
287 : void
288 1042 : RelationTruncate(Relation rel, BlockNumber nblocks)
289 : {
290 : bool fsm;
291 : bool vm;
292 1042 : bool need_fsm_vacuum = false;
293 : ForkNumber forks[MAX_FORKNUM];
294 : BlockNumber blocks[MAX_FORKNUM];
295 1042 : int nforks = 0;
296 : SMgrRelation reln;
297 :
298 : /*
299 : * Make sure smgr_targblock etc aren't pointing somewhere past new end.
300 : * (Note: don't rely on this reln pointer below this loop.)
301 : */
302 1042 : reln = RelationGetSmgr(rel);
303 1042 : reln->smgr_targblock = InvalidBlockNumber;
304 5210 : for (int i = 0; i <= MAX_FORKNUM; ++i)
305 4168 : reln->smgr_cached_nblocks[i] = InvalidBlockNumber;
306 :
307 : /* Prepare for truncation of MAIN fork of the relation */
308 1042 : forks[nforks] = MAIN_FORKNUM;
309 1042 : blocks[nforks] = nblocks;
310 1042 : nforks++;
311 :
312 : /* Prepare for truncation of the FSM if it exists */
313 1042 : fsm = smgrexists(RelationGetSmgr(rel), FSM_FORKNUM);
314 1042 : if (fsm)
315 : {
316 262 : blocks[nforks] = FreeSpaceMapPrepareTruncateRel(rel, nblocks);
317 262 : if (BlockNumberIsValid(blocks[nforks]))
318 : {
319 262 : forks[nforks] = FSM_FORKNUM;
320 262 : nforks++;
321 262 : need_fsm_vacuum = true;
322 : }
323 : }
324 :
325 : /* Prepare for truncation of the visibility map too if it exists */
326 1042 : vm = smgrexists(RelationGetSmgr(rel), VISIBILITYMAP_FORKNUM);
327 1042 : if (vm)
328 : {
329 262 : blocks[nforks] = visibilitymap_prepare_truncate(rel, nblocks);
330 262 : if (BlockNumberIsValid(blocks[nforks]))
331 : {
332 98 : forks[nforks] = VISIBILITYMAP_FORKNUM;
333 98 : nforks++;
334 : }
335 : }
336 :
337 1042 : RelationPreTruncate(rel);
338 :
339 : /*
340 : * Make sure that a concurrent checkpoint can't complete while truncation
341 : * is in progress.
342 : *
343 : * The truncation operation might drop buffers that the checkpoint
344 : * otherwise would have flushed. If it does, then it's essential that the
345 : * files actually get truncated on disk before the checkpoint record is
346 : * written. Otherwise, if reply begins from that checkpoint, the
347 : * to-be-truncated blocks might still exist on disk but have older
348 : * contents than expected, which can cause replay to fail. It's OK for the
349 : * blocks to not exist on disk at all, but not for them to have the wrong
350 : * contents.
351 : */
352 : Assert((MyProc->delayChkptFlags & DELAY_CHKPT_COMPLETE) == 0);
353 1042 : MyProc->delayChkptFlags |= DELAY_CHKPT_COMPLETE;
354 :
355 : /*
356 : * We WAL-log the truncation before actually truncating, which means
357 : * trouble if the truncation fails. If we then crash, the WAL replay
358 : * likely isn't going to succeed in the truncation either, and cause a
359 : * PANIC. It's tempting to put a critical section here, but that cure
360 : * would be worse than the disease. It would turn a usually harmless
361 : * failure to truncate, that might spell trouble at WAL replay, into a
362 : * certain PANIC.
363 : */
364 1042 : if (RelationNeedsWAL(rel))
365 : {
366 : /*
367 : * Make an XLOG entry reporting the file truncation.
368 : */
369 : XLogRecPtr lsn;
370 : xl_smgr_truncate xlrec;
371 :
372 378 : xlrec.blkno = nblocks;
373 378 : xlrec.rlocator = rel->rd_locator;
374 378 : xlrec.flags = SMGR_TRUNCATE_ALL;
375 :
376 378 : XLogBeginInsert();
377 378 : XLogRegisterData((char *) &xlrec, sizeof(xlrec));
378 :
379 378 : lsn = XLogInsert(RM_SMGR_ID,
380 : XLOG_SMGR_TRUNCATE | XLR_SPECIAL_REL_UPDATE);
381 :
382 : /*
383 : * Flush, because otherwise the truncation of the main relation might
384 : * hit the disk before the WAL record, and the truncation of the FSM
385 : * or visibility map. If we crashed during that window, we'd be left
386 : * with a truncated heap, but the FSM or visibility map would still
387 : * contain entries for the non-existent heap pages.
388 : */
389 378 : if (fsm || vm)
390 242 : XLogFlush(lsn);
391 : }
392 :
393 : /*
394 : * This will first remove any buffers from the buffer pool that should no
395 : * longer exist after truncation is complete, and then truncate the
396 : * corresponding files on disk.
397 : */
398 1042 : smgrtruncate(RelationGetSmgr(rel), forks, nforks, blocks);
399 :
400 : /* We've done all the critical work, so checkpoints are OK now. */
401 1042 : MyProc->delayChkptFlags &= ~DELAY_CHKPT_COMPLETE;
402 :
403 : /*
404 : * Update upper-level FSM pages to account for the truncation. This is
405 : * important because the just-truncated pages were likely marked as
406 : * all-free, and would be preferentially selected.
407 : *
408 : * NB: There's no point in delaying checkpoints until this is done.
409 : * Because the FSM is not WAL-logged, we have to be prepared for the
410 : * possibility of corruption after a crash anyway.
411 : */
412 1042 : if (need_fsm_vacuum)
413 262 : FreeSpaceMapVacuumRange(rel, nblocks, InvalidBlockNumber);
414 1042 : }
415 :
416 : /*
417 : * RelationPreTruncate
418 : * Perform AM-independent work before a physical truncation.
419 : *
420 : * If an access method's relation_nontransactional_truncate does not call
421 : * RelationTruncate(), it must call this before decreasing the table size.
422 : */
423 : void
424 1042 : RelationPreTruncate(Relation rel)
425 : {
426 : PendingRelSync *pending;
427 :
428 1042 : if (!pendingSyncHash)
429 1036 : return;
430 :
431 6 : pending = hash_search(pendingSyncHash,
432 6 : &(RelationGetSmgr(rel)->smgr_rlocator.locator),
433 : HASH_FIND, NULL);
434 6 : if (pending)
435 6 : pending->is_truncated = true;
436 : }
437 :
438 : /*
439 : * Copy a fork's data, block by block.
440 : *
441 : * Note that this requires that there is no dirty data in shared buffers. If
442 : * it's possible that there are, callers need to flush those using
443 : * e.g. FlushRelationBuffers(rel).
444 : *
445 : * Also note that this is frequently called via locutions such as
446 : * RelationCopyStorage(RelationGetSmgr(rel), ...);
447 : * That's safe only because we perform only smgr and WAL operations here.
448 : * If we invoked anything else, a relcache flush could cause our SMgrRelation
449 : * argument to become a dangling pointer.
450 : */
451 : void
452 178 : RelationCopyStorage(SMgrRelation src, SMgrRelation dst,
453 : ForkNumber forkNum, char relpersistence)
454 : {
455 : bool use_wal;
456 : bool copying_initfork;
457 : BlockNumber nblocks;
458 : BlockNumber blkno;
459 : BulkWriteState *bulkstate;
460 :
461 : /*
462 : * The init fork for an unlogged relation in many respects has to be
463 : * treated the same as normal relation, changes need to be WAL logged and
464 : * it needs to be synced to disk.
465 : */
466 178 : copying_initfork = relpersistence == RELPERSISTENCE_UNLOGGED &&
467 : forkNum == INIT_FORKNUM;
468 :
469 : /*
470 : * We need to log the copied data in WAL iff WAL archiving/streaming is
471 : * enabled AND it's a permanent relation. This gives the same answer as
472 : * "RelationNeedsWAL(rel) || copying_initfork", because we know the
473 : * current operation created new relation storage.
474 : */
475 194 : use_wal = XLogIsNeeded() &&
476 16 : (relpersistence == RELPERSISTENCE_PERMANENT || copying_initfork);
477 :
478 178 : bulkstate = smgr_bulk_start_smgr(dst, forkNum, use_wal);
479 :
480 178 : nblocks = smgrnblocks(src, forkNum);
481 :
482 1372 : for (blkno = 0; blkno < nblocks; blkno++)
483 : {
484 : BulkWriteBuffer buf;
485 :
486 : /* If we got a cancel signal during the copy of the data, quit */
487 1194 : CHECK_FOR_INTERRUPTS();
488 :
489 1194 : buf = smgr_bulk_get_buf(bulkstate);
490 1194 : smgrread(src, forkNum, blkno, (Page) buf);
491 :
492 1194 : if (!PageIsVerifiedExtended((Page) buf, blkno,
493 : PIV_LOG_WARNING | PIV_REPORT_STAT))
494 : {
495 : /*
496 : * For paranoia's sake, capture the file path before invoking the
497 : * ereport machinery. This guards against the possibility of a
498 : * relcache flush caused by, e.g., an errcontext callback.
499 : * (errcontext callbacks shouldn't be risking any such thing, but
500 : * people have been known to forget that rule.)
501 : */
502 0 : char *relpath = relpathbackend(src->smgr_rlocator.locator,
503 : src->smgr_rlocator.backend,
504 : forkNum);
505 :
506 0 : ereport(ERROR,
507 : (errcode(ERRCODE_DATA_CORRUPTED),
508 : errmsg("invalid page in block %u of relation %s",
509 : blkno, relpath)));
510 : }
511 :
512 : /*
513 : * Queue the page for WAL-logging and writing out. Unfortunately we
514 : * don't know what kind of a page this is, so we have to log the full
515 : * page including any unused space.
516 : */
517 1194 : smgr_bulk_write(bulkstate, blkno, buf, false);
518 : }
519 178 : smgr_bulk_finish(bulkstate);
520 178 : }
521 :
522 : /*
523 : * RelFileLocatorSkippingWAL
524 : * Check if a BM_PERMANENT relfilelocator is using WAL.
525 : *
526 : * Changes to certain relations must not write WAL; see "Skipping WAL for
527 : * New RelFileLocator" in src/backend/access/transam/README. Though it is
528 : * known from Relation efficiently, this function is intended for the code
529 : * paths not having access to Relation.
530 : */
531 : bool
532 162114 : RelFileLocatorSkippingWAL(RelFileLocator rlocator)
533 : {
534 173798 : if (!pendingSyncHash ||
535 11684 : hash_search(pendingSyncHash, &rlocator, HASH_FIND, NULL) == NULL)
536 158536 : return false;
537 :
538 3578 : return true;
539 : }
540 :
541 : /*
542 : * EstimatePendingSyncsSpace
543 : * Estimate space needed to pass syncs to parallel workers.
544 : */
545 : Size
546 886 : EstimatePendingSyncsSpace(void)
547 : {
548 : long entries;
549 :
550 886 : entries = pendingSyncHash ? hash_get_num_entries(pendingSyncHash) : 0;
551 886 : return mul_size(1 + entries, sizeof(RelFileLocator));
552 : }
553 :
554 : /*
555 : * SerializePendingSyncs
556 : * Serialize syncs for parallel workers.
557 : */
558 : void
559 886 : SerializePendingSyncs(Size maxSize, char *startAddress)
560 : {
561 : HTAB *tmphash;
562 : HASHCTL ctl;
563 : HASH_SEQ_STATUS scan;
564 : PendingRelSync *sync;
565 : PendingRelDelete *delete;
566 : RelFileLocator *src;
567 886 : RelFileLocator *dest = (RelFileLocator *) startAddress;
568 :
569 886 : if (!pendingSyncHash)
570 694 : goto terminate;
571 :
572 : /* Create temporary hash to collect active relfilelocators */
573 192 : ctl.keysize = sizeof(RelFileLocator);
574 192 : ctl.entrysize = sizeof(RelFileLocator);
575 192 : ctl.hcxt = CurrentMemoryContext;
576 192 : tmphash = hash_create("tmp relfilelocators",
577 : hash_get_num_entries(pendingSyncHash), &ctl,
578 : HASH_ELEM | HASH_BLOBS | HASH_CONTEXT);
579 :
580 : /* collect all rlocator from pending syncs */
581 192 : hash_seq_init(&scan, pendingSyncHash);
582 1654 : while ((sync = (PendingRelSync *) hash_seq_search(&scan)))
583 1462 : (void) hash_search(tmphash, &sync->rlocator, HASH_ENTER, NULL);
584 :
585 : /* remove deleted rnodes */
586 1994 : for (delete = pendingDeletes; delete != NULL; delete = delete->next)
587 1802 : if (delete->atCommit)
588 330 : (void) hash_search(tmphash, &delete->rlocator,
589 : HASH_REMOVE, NULL);
590 :
591 192 : hash_seq_init(&scan, tmphash);
592 1332 : while ((src = (RelFileLocator *) hash_seq_search(&scan)))
593 1140 : *dest++ = *src;
594 :
595 192 : hash_destroy(tmphash);
596 :
597 886 : terminate:
598 886 : MemSet(dest, 0, sizeof(RelFileLocator));
599 886 : }
600 :
601 : /*
602 : * RestorePendingSyncs
603 : * Restore syncs within a parallel worker.
604 : *
605 : * RelationNeedsWAL() and RelFileLocatorSkippingWAL() must offer the correct
606 : * answer to parallel workers. Only smgrDoPendingSyncs() reads the
607 : * is_truncated field, at end of transaction. Hence, don't restore it.
608 : */
609 : void
610 2712 : RestorePendingSyncs(char *startAddress)
611 : {
612 : RelFileLocator *rlocator;
613 :
614 : Assert(pendingSyncHash == NULL);
615 6308 : for (rlocator = (RelFileLocator *) startAddress; rlocator->relNumber != 0;
616 3596 : rlocator++)
617 3596 : AddPendingSync(rlocator);
618 2712 : }
619 :
620 : /*
621 : * smgrDoPendingDeletes() -- Take care of relation deletes at end of xact.
622 : *
623 : * This also runs when aborting a subxact; we want to clean up a failed
624 : * subxact immediately.
625 : *
626 : * Note: It's possible that we're being asked to remove a relation that has
627 : * no physical storage in any fork. In particular, it's possible that we're
628 : * cleaning up an old temporary relation for which RemovePgTempFiles has
629 : * already recovered the physical storage.
630 : */
631 : void
632 755500 : smgrDoPendingDeletes(bool isCommit)
633 : {
634 755500 : int nestLevel = GetCurrentTransactionNestLevel();
635 : PendingRelDelete *pending;
636 : PendingRelDelete *prev;
637 : PendingRelDelete *next;
638 755500 : int nrels = 0,
639 755500 : maxrels = 0;
640 755500 : SMgrRelation *srels = NULL;
641 :
642 755500 : prev = NULL;
643 945246 : for (pending = pendingDeletes; pending != NULL; pending = next)
644 : {
645 189746 : next = pending->next;
646 189746 : if (pending->nestLevel < nestLevel)
647 : {
648 : /* outer-level entries should not be processed yet */
649 8228 : prev = pending;
650 : }
651 : else
652 : {
653 : /* unlink list entry first, so we don't retry on failure */
654 181518 : if (prev)
655 0 : prev->next = next;
656 : else
657 181518 : pendingDeletes = next;
658 : /* do deletion if called for */
659 181518 : if (pending->atCommit == isCommit)
660 : {
661 : SMgrRelation srel;
662 :
663 72418 : srel = smgropen(pending->rlocator, pending->procNumber);
664 :
665 : /* allocate the initial array, or extend it, if needed */
666 72418 : if (maxrels == 0)
667 : {
668 20762 : maxrels = 8;
669 20762 : srels = palloc(sizeof(SMgrRelation) * maxrels);
670 : }
671 51656 : else if (maxrels <= nrels)
672 : {
673 1702 : maxrels *= 2;
674 1702 : srels = repalloc(srels, sizeof(SMgrRelation) * maxrels);
675 : }
676 :
677 72418 : srels[nrels++] = srel;
678 : }
679 : /* must explicitly free the list entry */
680 181518 : pfree(pending);
681 : /* prev does not change */
682 : }
683 : }
684 :
685 755500 : if (nrels > 0)
686 : {
687 20762 : smgrdounlinkall(srels, nrels, false);
688 :
689 93180 : for (int i = 0; i < nrels; i++)
690 72418 : smgrclose(srels[i]);
691 :
692 20762 : pfree(srels);
693 : }
694 755500 : }
695 :
696 : /*
697 : * smgrDoPendingSyncs() -- Take care of relation syncs at end of xact.
698 : */
699 : void
700 747382 : smgrDoPendingSyncs(bool isCommit, bool isParallelWorker)
701 : {
702 : PendingRelDelete *pending;
703 747382 : int nrels = 0,
704 747382 : maxrels = 0;
705 747382 : SMgrRelation *srels = NULL;
706 : HASH_SEQ_STATUS scan;
707 : PendingRelSync *pendingsync;
708 :
709 : Assert(GetCurrentTransactionNestLevel() == 1);
710 :
711 747382 : if (!pendingSyncHash)
712 736508 : return; /* no relation needs sync */
713 :
714 : /* Abort -- just throw away all pending syncs */
715 11802 : if (!isCommit)
716 : {
717 530 : pendingSyncHash = NULL;
718 530 : return;
719 : }
720 :
721 : AssertPendingSyncs_RelationCache();
722 :
723 : /* Parallel worker -- just throw away all pending syncs */
724 11272 : if (isParallelWorker)
725 : {
726 398 : pendingSyncHash = NULL;
727 398 : return;
728 : }
729 :
730 : /* Skip syncing nodes that smgrDoPendingDeletes() will delete. */
731 43328 : for (pending = pendingDeletes; pending != NULL; pending = pending->next)
732 32454 : if (pending->atCommit)
733 7292 : (void) hash_search(pendingSyncHash, &pending->rlocator,
734 : HASH_REMOVE, NULL);
735 :
736 10874 : hash_seq_init(&scan, pendingSyncHash);
737 75340 : while ((pendingsync = (PendingRelSync *) hash_seq_search(&scan)))
738 : {
739 : ForkNumber fork;
740 : BlockNumber nblocks[MAX_FORKNUM + 1];
741 64466 : BlockNumber total_blocks = 0;
742 : SMgrRelation srel;
743 :
744 64466 : srel = smgropen(pendingsync->rlocator, INVALID_PROC_NUMBER);
745 :
746 : /*
747 : * We emit newpage WAL records for smaller relations.
748 : *
749 : * Small WAL records have a chance to be flushed along with other
750 : * backends' WAL records. We emit WAL records instead of syncing for
751 : * files that are smaller than a certain threshold, expecting faster
752 : * commit. The threshold is defined by the GUC wal_skip_threshold.
753 : */
754 64466 : if (!pendingsync->is_truncated)
755 : {
756 322330 : for (fork = 0; fork <= MAX_FORKNUM; fork++)
757 : {
758 257864 : if (smgrexists(srel, fork))
759 : {
760 77990 : BlockNumber n = smgrnblocks(srel, fork);
761 :
762 : /* we shouldn't come here for unlogged relations */
763 : Assert(fork != INIT_FORKNUM);
764 77990 : nblocks[fork] = n;
765 77990 : total_blocks += n;
766 : }
767 : else
768 179874 : nblocks[fork] = InvalidBlockNumber;
769 : }
770 : }
771 :
772 : /*
773 : * Sync file or emit WAL records for its contents.
774 : *
775 : * Although we emit WAL record if the file is small enough, do file
776 : * sync regardless of the size if the file has experienced a
777 : * truncation. It is because the file would be followed by trailing
778 : * garbage blocks after a crash recovery if, while a past longer file
779 : * had been flushed out, we omitted syncing-out of the file and
780 : * emitted WAL instead. You might think that we could choose WAL if
781 : * the current main fork is longer than ever, but there's a case where
782 : * main fork is longer than ever but FSM fork gets shorter.
783 : */
784 64466 : if (pendingsync->is_truncated ||
785 64466 : total_blocks * BLCKSZ / 1024 >= wal_skip_threshold)
786 : {
787 : /* allocate the initial array, or extend it, if needed */
788 18 : if (maxrels == 0)
789 : {
790 18 : maxrels = 8;
791 18 : srels = palloc(sizeof(SMgrRelation) * maxrels);
792 : }
793 0 : else if (maxrels <= nrels)
794 : {
795 0 : maxrels *= 2;
796 0 : srels = repalloc(srels, sizeof(SMgrRelation) * maxrels);
797 : }
798 :
799 18 : srels[nrels++] = srel;
800 : }
801 : else
802 : {
803 : /* Emit WAL records for all blocks. The file is small enough. */
804 322240 : for (fork = 0; fork <= MAX_FORKNUM; fork++)
805 : {
806 257792 : int n = nblocks[fork];
807 : Relation rel;
808 :
809 257792 : if (!BlockNumberIsValid(n))
810 179822 : continue;
811 :
812 : /*
813 : * Emit WAL for the whole file. Unfortunately we don't know
814 : * what kind of a page this is, so we have to log the full
815 : * page including any unused space. ReadBufferExtended()
816 : * counts some pgstat events; unfortunately, we discard them.
817 : */
818 77970 : rel = CreateFakeRelcacheEntry(srel->smgr_rlocator.locator);
819 77970 : log_newpage_range(rel, fork, 0, n, false);
820 77970 : FreeFakeRelcacheEntry(rel);
821 : }
822 : }
823 : }
824 :
825 10874 : pendingSyncHash = NULL;
826 :
827 10874 : if (nrels > 0)
828 : {
829 18 : smgrdosyncall(srels, nrels);
830 18 : pfree(srels);
831 : }
832 : }
833 :
834 : /*
835 : * smgrGetPendingDeletes() -- Get a list of non-temp relations to be deleted.
836 : *
837 : * The return value is the number of relations scheduled for termination.
838 : * *ptr is set to point to a freshly-palloc'd array of RelFileLocators.
839 : * If there are no relations to be deleted, *ptr is set to NULL.
840 : *
841 : * Only non-temporary relations are included in the returned list. This is OK
842 : * because the list is used only in contexts where temporary relations don't
843 : * matter: we're either writing to the two-phase state file (and transactions
844 : * that have touched temp tables can't be prepared) or we're writing to xlog
845 : * (and all temporary files will be zapped if we restart anyway, so no need
846 : * for redo to do it also).
847 : *
848 : * Note that the list does not include anything scheduled for termination
849 : * by upper-level transactions.
850 : */
851 : int
852 709530 : smgrGetPendingDeletes(bool forCommit, RelFileLocator **ptr)
853 : {
854 709530 : int nestLevel = GetCurrentTransactionNestLevel();
855 : int nrels;
856 : RelFileLocator *rptr;
857 : PendingRelDelete *pending;
858 :
859 709530 : nrels = 0;
860 896432 : for (pending = pendingDeletes; pending != NULL; pending = pending->next)
861 : {
862 186902 : if (pending->nestLevel >= nestLevel && pending->atCommit == forCommit
863 72538 : && pending->procNumber == INVALID_PROC_NUMBER)
864 66540 : nrels++;
865 : }
866 709530 : if (nrels == 0)
867 : {
868 690214 : *ptr = NULL;
869 690214 : return 0;
870 : }
871 19316 : rptr = (RelFileLocator *) palloc(nrels * sizeof(RelFileLocator));
872 19316 : *ptr = rptr;
873 102616 : for (pending = pendingDeletes; pending != NULL; pending = pending->next)
874 : {
875 83300 : if (pending->nestLevel >= nestLevel && pending->atCommit == forCommit
876 66688 : && pending->procNumber == INVALID_PROC_NUMBER)
877 : {
878 66540 : *rptr = pending->rlocator;
879 66540 : rptr++;
880 : }
881 : }
882 19316 : return nrels;
883 : }
884 :
885 : /*
886 : * PostPrepare_smgr -- Clean up after a successful PREPARE
887 : *
888 : * What we have to do here is throw away the in-memory state about pending
889 : * relation deletes. It's all been recorded in the 2PC state file and
890 : * it's no longer smgr's job to worry about it.
891 : */
892 : void
893 744 : PostPrepare_smgr(void)
894 : {
895 : PendingRelDelete *pending;
896 : PendingRelDelete *next;
897 :
898 864 : for (pending = pendingDeletes; pending != NULL; pending = next)
899 : {
900 120 : next = pending->next;
901 120 : pendingDeletes = next;
902 : /* must explicitly free the list entry */
903 120 : pfree(pending);
904 : }
905 744 : }
906 :
907 :
908 : /*
909 : * AtSubCommit_smgr() --- Take care of subtransaction commit.
910 : *
911 : * Reassign all items in the pending-deletes list to the parent transaction.
912 : */
913 : void
914 10720 : AtSubCommit_smgr(void)
915 : {
916 10720 : int nestLevel = GetCurrentTransactionNestLevel();
917 : PendingRelDelete *pending;
918 :
919 11176 : for (pending = pendingDeletes; pending != NULL; pending = pending->next)
920 : {
921 456 : if (pending->nestLevel >= nestLevel)
922 214 : pending->nestLevel = nestLevel - 1;
923 : }
924 10720 : }
925 :
926 : /*
927 : * AtSubAbort_smgr() --- Take care of subtransaction abort.
928 : *
929 : * Delete created relations and forget about deleted relations.
930 : * We can execute these operations immediately because we know this
931 : * subtransaction will not commit.
932 : */
933 : void
934 9268 : AtSubAbort_smgr(void)
935 : {
936 9268 : smgrDoPendingDeletes(false);
937 9268 : }
938 :
939 : void
940 30860 : smgr_redo(XLogReaderState *record)
941 : {
942 30860 : XLogRecPtr lsn = record->EndRecPtr;
943 30860 : uint8 info = XLogRecGetInfo(record) & ~XLR_INFO_MASK;
944 :
945 : /* Backup blocks are not used in smgr records */
946 : Assert(!XLogRecHasAnyBlockRefs(record));
947 :
948 30860 : if (info == XLOG_SMGR_CREATE)
949 : {
950 30766 : xl_smgr_create *xlrec = (xl_smgr_create *) XLogRecGetData(record);
951 : SMgrRelation reln;
952 :
953 30766 : reln = smgropen(xlrec->rlocator, INVALID_PROC_NUMBER);
954 30766 : smgrcreate(reln, xlrec->forkNum, true);
955 : }
956 94 : else if (info == XLOG_SMGR_TRUNCATE)
957 : {
958 94 : xl_smgr_truncate *xlrec = (xl_smgr_truncate *) XLogRecGetData(record);
959 : SMgrRelation reln;
960 : Relation rel;
961 : ForkNumber forks[MAX_FORKNUM];
962 : BlockNumber blocks[MAX_FORKNUM];
963 94 : int nforks = 0;
964 94 : bool need_fsm_vacuum = false;
965 :
966 94 : reln = smgropen(xlrec->rlocator, INVALID_PROC_NUMBER);
967 :
968 : /*
969 : * Forcibly create relation if it doesn't exist (which suggests that
970 : * it was dropped somewhere later in the WAL sequence). As in
971 : * XLogReadBufferForRedo, we prefer to recreate the rel and replay the
972 : * log as best we can until the drop is seen.
973 : */
974 94 : smgrcreate(reln, MAIN_FORKNUM, true);
975 :
976 : /*
977 : * Before we perform the truncation, update minimum recovery point to
978 : * cover this WAL record. Once the relation is truncated, there's no
979 : * going back. The buffer manager enforces the WAL-first rule for
980 : * normal updates to relation files, so that the minimum recovery
981 : * point is always updated before the corresponding change in the data
982 : * file is flushed to disk. We have to do the same manually here.
983 : *
984 : * Doing this before the truncation means that if the truncation fails
985 : * for some reason, you cannot start up the system even after restart,
986 : * until you fix the underlying situation so that the truncation will
987 : * succeed. Alternatively, we could update the minimum recovery point
988 : * after truncation, but that would leave a small window where the
989 : * WAL-first rule could be violated.
990 : */
991 94 : XLogFlush(lsn);
992 :
993 : /* Prepare for truncation of MAIN fork */
994 94 : if ((xlrec->flags & SMGR_TRUNCATE_HEAP) != 0)
995 : {
996 94 : forks[nforks] = MAIN_FORKNUM;
997 94 : blocks[nforks] = xlrec->blkno;
998 94 : nforks++;
999 :
1000 : /* Also tell xlogutils.c about it */
1001 94 : XLogTruncateRelation(xlrec->rlocator, MAIN_FORKNUM, xlrec->blkno);
1002 : }
1003 :
1004 : /* Prepare for truncation of FSM and VM too */
1005 94 : rel = CreateFakeRelcacheEntry(xlrec->rlocator);
1006 :
1007 188 : if ((xlrec->flags & SMGR_TRUNCATE_FSM) != 0 &&
1008 94 : smgrexists(reln, FSM_FORKNUM))
1009 : {
1010 58 : blocks[nforks] = FreeSpaceMapPrepareTruncateRel(rel, xlrec->blkno);
1011 58 : if (BlockNumberIsValid(blocks[nforks]))
1012 : {
1013 58 : forks[nforks] = FSM_FORKNUM;
1014 58 : nforks++;
1015 58 : need_fsm_vacuum = true;
1016 : }
1017 : }
1018 188 : if ((xlrec->flags & SMGR_TRUNCATE_VM) != 0 &&
1019 94 : smgrexists(reln, VISIBILITYMAP_FORKNUM))
1020 : {
1021 48 : blocks[nforks] = visibilitymap_prepare_truncate(rel, xlrec->blkno);
1022 48 : if (BlockNumberIsValid(blocks[nforks]))
1023 : {
1024 14 : forks[nforks] = VISIBILITYMAP_FORKNUM;
1025 14 : nforks++;
1026 : }
1027 : }
1028 :
1029 : /* Do the real work to truncate relation forks */
1030 94 : if (nforks > 0)
1031 94 : smgrtruncate(reln, forks, nforks, blocks);
1032 :
1033 : /*
1034 : * Update upper-level FSM pages to account for the truncation. This is
1035 : * important because the just-truncated pages were likely marked as
1036 : * all-free, and would be preferentially selected.
1037 : */
1038 94 : if (need_fsm_vacuum)
1039 58 : FreeSpaceMapVacuumRange(rel, xlrec->blkno,
1040 : InvalidBlockNumber);
1041 :
1042 94 : FreeFakeRelcacheEntry(rel);
1043 : }
1044 : else
1045 0 : elog(PANIC, "smgr_redo: unknown op code %u", info);
1046 30860 : }
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