Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * hio.c
4 : * POSTGRES heap access method input/output code.
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/access/heap/hio.c
12 : *
13 : *-------------------------------------------------------------------------
14 : */
15 :
16 : #include "postgres.h"
17 :
18 : #include "access/heapam.h"
19 : #include "access/hio.h"
20 : #include "access/htup_details.h"
21 : #include "access/visibilitymap.h"
22 : #include "storage/bufmgr.h"
23 : #include "storage/freespace.h"
24 : #include "storage/lmgr.h"
25 :
26 :
27 : /*
28 : * RelationPutHeapTuple - place tuple at specified page
29 : *
30 : * !!! EREPORT(ERROR) IS DISALLOWED HERE !!! Must PANIC on failure!!!
31 : *
32 : * Note - caller must hold BUFFER_LOCK_EXCLUSIVE on the buffer.
33 : */
34 : void
35 18403076 : RelationPutHeapTuple(Relation relation,
36 : Buffer buffer,
37 : HeapTuple tuple,
38 : bool token)
39 : {
40 : Page pageHeader;
41 : OffsetNumber offnum;
42 :
43 : /*
44 : * A tuple that's being inserted speculatively should already have its
45 : * token set.
46 : */
47 : Assert(!token || HeapTupleHeaderIsSpeculative(tuple->t_data));
48 :
49 : /*
50 : * Do not allow tuples with invalid combinations of hint bits to be placed
51 : * on a page. This combination is detected as corruption by the
52 : * contrib/amcheck logic, so if you disable this assertion, make
53 : * corresponding changes there.
54 : */
55 : Assert(!((tuple->t_data->t_infomask & HEAP_XMAX_COMMITTED) &&
56 : (tuple->t_data->t_infomask & HEAP_XMAX_IS_MULTI)));
57 :
58 : /* Add the tuple to the page */
59 18403076 : pageHeader = BufferGetPage(buffer);
60 :
61 18403076 : offnum = PageAddItem(pageHeader, (Item) tuple->t_data,
62 : tuple->t_len, InvalidOffsetNumber, false, true);
63 :
64 18403076 : if (offnum == InvalidOffsetNumber)
65 0 : elog(PANIC, "failed to add tuple to page");
66 :
67 : /* Update tuple->t_self to the actual position where it was stored */
68 18403076 : ItemPointerSet(&(tuple->t_self), BufferGetBlockNumber(buffer), offnum);
69 :
70 : /*
71 : * Insert the correct position into CTID of the stored tuple, too (unless
72 : * this is a speculative insertion, in which case the token is held in
73 : * CTID field instead)
74 : */
75 18403076 : if (!token)
76 : {
77 18399050 : ItemId itemId = PageGetItemId(pageHeader, offnum);
78 18399050 : HeapTupleHeader item = (HeapTupleHeader) PageGetItem(pageHeader, itemId);
79 :
80 18399050 : item->t_ctid = tuple->t_self;
81 : }
82 18403076 : }
83 :
84 : /*
85 : * Read in a buffer in mode, using bulk-insert strategy if bistate isn't NULL.
86 : */
87 : static Buffer
88 15771638 : ReadBufferBI(Relation relation, BlockNumber targetBlock,
89 : ReadBufferMode mode, BulkInsertState bistate)
90 : {
91 : Buffer buffer;
92 :
93 : /* If not bulk-insert, exactly like ReadBuffer */
94 15771638 : if (!bistate)
95 13450854 : return ReadBufferExtended(relation, MAIN_FORKNUM, targetBlock,
96 : mode, NULL);
97 :
98 : /* If we have the desired block already pinned, re-pin and return it */
99 2320784 : if (bistate->current_buf != InvalidBuffer)
100 : {
101 2260436 : if (BufferGetBlockNumber(bistate->current_buf) == targetBlock)
102 : {
103 : /*
104 : * Currently the LOCK variants are only used for extending
105 : * relation, which should never reach this branch.
106 : */
107 : Assert(mode != RBM_ZERO_AND_LOCK &&
108 : mode != RBM_ZERO_AND_CLEANUP_LOCK);
109 :
110 2236186 : IncrBufferRefCount(bistate->current_buf);
111 2236186 : return bistate->current_buf;
112 : }
113 : /* ... else drop the old buffer */
114 24250 : ReleaseBuffer(bistate->current_buf);
115 24250 : bistate->current_buf = InvalidBuffer;
116 : }
117 :
118 : /* Perform a read using the buffer strategy */
119 84598 : buffer = ReadBufferExtended(relation, MAIN_FORKNUM, targetBlock,
120 : mode, bistate->strategy);
121 :
122 : /* Save the selected block as target for future inserts */
123 84598 : IncrBufferRefCount(buffer);
124 84598 : bistate->current_buf = buffer;
125 :
126 84598 : return buffer;
127 : }
128 :
129 : /*
130 : * For each heap page which is all-visible, acquire a pin on the appropriate
131 : * visibility map page, if we haven't already got one.
132 : *
133 : * To avoid complexity in the callers, either buffer1 or buffer2 may be
134 : * InvalidBuffer if only one buffer is involved. For the same reason, block2
135 : * may be smaller than block1.
136 : *
137 : * Returns whether buffer locks were temporarily released.
138 : */
139 : static bool
140 16062594 : GetVisibilityMapPins(Relation relation, Buffer buffer1, Buffer buffer2,
141 : BlockNumber block1, BlockNumber block2,
142 : Buffer *vmbuffer1, Buffer *vmbuffer2)
143 : {
144 : bool need_to_pin_buffer1;
145 : bool need_to_pin_buffer2;
146 16062594 : bool released_locks = false;
147 :
148 : /*
149 : * Swap buffers around to handle case of a single block/buffer, and to
150 : * handle if lock ordering rules require to lock block2 first.
151 : */
152 32124188 : if (!BufferIsValid(buffer1) ||
153 16351550 : (BufferIsValid(buffer2) && block1 > block2))
154 : {
155 276306 : Buffer tmpbuf = buffer1;
156 276306 : Buffer *tmpvmbuf = vmbuffer1;
157 276306 : BlockNumber tmpblock = block1;
158 :
159 276306 : buffer1 = buffer2;
160 276306 : vmbuffer1 = vmbuffer2;
161 276306 : block1 = block2;
162 :
163 276306 : buffer2 = tmpbuf;
164 276306 : vmbuffer2 = tmpvmbuf;
165 276306 : block2 = tmpblock;
166 : }
167 :
168 : Assert(BufferIsValid(buffer1));
169 : Assert(buffer2 == InvalidBuffer || block1 <= block2);
170 :
171 : while (1)
172 : {
173 : /* Figure out which pins we need but don't have. */
174 16062594 : need_to_pin_buffer1 = PageIsAllVisible(BufferGetPage(buffer1))
175 16062594 : && !visibilitymap_pin_ok(block1, *vmbuffer1);
176 16062594 : need_to_pin_buffer2 = buffer2 != InvalidBuffer
177 289956 : && PageIsAllVisible(BufferGetPage(buffer2))
178 16352550 : && !visibilitymap_pin_ok(block2, *vmbuffer2);
179 16062594 : if (!need_to_pin_buffer1 && !need_to_pin_buffer2)
180 16062594 : break;
181 :
182 : /* We must unlock both buffers before doing any I/O. */
183 0 : released_locks = true;
184 0 : LockBuffer(buffer1, BUFFER_LOCK_UNLOCK);
185 0 : if (buffer2 != InvalidBuffer && buffer2 != buffer1)
186 0 : LockBuffer(buffer2, BUFFER_LOCK_UNLOCK);
187 :
188 : /* Get pins. */
189 0 : if (need_to_pin_buffer1)
190 0 : visibilitymap_pin(relation, block1, vmbuffer1);
191 0 : if (need_to_pin_buffer2)
192 0 : visibilitymap_pin(relation, block2, vmbuffer2);
193 :
194 : /* Relock buffers. */
195 0 : LockBuffer(buffer1, BUFFER_LOCK_EXCLUSIVE);
196 0 : if (buffer2 != InvalidBuffer && buffer2 != buffer1)
197 0 : LockBuffer(buffer2, BUFFER_LOCK_EXCLUSIVE);
198 :
199 : /*
200 : * If there are two buffers involved and we pinned just one of them,
201 : * it's possible that the second one became all-visible while we were
202 : * busy pinning the first one. If it looks like that's a possible
203 : * scenario, we'll need to make a second pass through this loop.
204 : */
205 0 : if (buffer2 == InvalidBuffer || buffer1 == buffer2
206 0 : || (need_to_pin_buffer1 && need_to_pin_buffer2))
207 : break;
208 : }
209 :
210 16062594 : return released_locks;
211 : }
212 :
213 : /*
214 : * Extend the relation. By multiple pages, if beneficial.
215 : *
216 : * If the caller needs multiple pages (num_pages > 1), we always try to extend
217 : * by at least that much.
218 : *
219 : * If there is contention on the extension lock, we don't just extend "for
220 : * ourselves", but we try to help others. We can do so by adding empty pages
221 : * into the FSM. Typically there is no contention when we can't use the FSM.
222 : *
223 : * We do have to limit the number of pages to extend by to some value, as the
224 : * buffers for all the extended pages need to, temporarily, be pinned. For now
225 : * we define MAX_BUFFERS_TO_EXTEND_BY to be 64 buffers, it's hard to see
226 : * benefits with higher numbers. This partially is because copyfrom.c's
227 : * MAX_BUFFERED_TUPLES / MAX_BUFFERED_BYTES prevents larger multi_inserts.
228 : *
229 : * Returns a buffer for a newly extended block. If possible, the buffer is
230 : * returned exclusively locked. *did_unlock is set to true if the lock had to
231 : * be released, false otherwise.
232 : *
233 : *
234 : * XXX: It would likely be beneficial for some workloads to extend more
235 : * aggressively, e.g. using a heuristic based on the relation size.
236 : */
237 : static Buffer
238 190896 : RelationAddBlocks(Relation relation, BulkInsertState bistate,
239 : int num_pages, bool use_fsm, bool *did_unlock)
240 : {
241 : #define MAX_BUFFERS_TO_EXTEND_BY 64
242 : Buffer victim_buffers[MAX_BUFFERS_TO_EXTEND_BY];
243 190896 : BlockNumber first_block = InvalidBlockNumber;
244 190896 : BlockNumber last_block = InvalidBlockNumber;
245 : uint32 extend_by_pages;
246 : uint32 not_in_fsm_pages;
247 : Buffer buffer;
248 : Page page;
249 :
250 : /*
251 : * Determine by how many pages to try to extend by.
252 : */
253 190896 : if (bistate == NULL && !use_fsm)
254 : {
255 : /*
256 : * If we have neither bistate, nor can use the FSM, we can't bulk
257 : * extend - there'd be no way to find the additional pages.
258 : */
259 326 : extend_by_pages = 1;
260 : }
261 : else
262 : {
263 : uint32 waitcount;
264 :
265 : /*
266 : * Try to extend at least by the number of pages the caller needs. We
267 : * can remember the additional pages (either via FSM or bistate).
268 : */
269 190570 : extend_by_pages = num_pages;
270 :
271 190570 : if (!RELATION_IS_LOCAL(relation))
272 112994 : waitcount = RelationExtensionLockWaiterCount(relation);
273 : else
274 77576 : waitcount = 0;
275 :
276 : /*
277 : * Multiply the number of pages to extend by the number of waiters. Do
278 : * this even if we're not using the FSM, as it still relieves
279 : * contention, by deferring the next time this backend needs to
280 : * extend. In that case the extended pages will be found via
281 : * bistate->next_free.
282 : */
283 190570 : extend_by_pages += extend_by_pages * waitcount;
284 :
285 : /* ---
286 : * If we previously extended using the same bistate, it's very likely
287 : * we'll extend some more. Try to extend by as many pages as
288 : * before. This can be important for performance for several reasons,
289 : * including:
290 : *
291 : * - It prevents mdzeroextend() switching between extending the
292 : * relation in different ways, which is inefficient for some
293 : * filesystems.
294 : *
295 : * - Contention is often intermittent. Even if we currently don't see
296 : * other waiters (see above), extending by larger amounts can
297 : * prevent future contention.
298 : * ---
299 : */
300 190570 : if (bistate)
301 11426 : extend_by_pages = Max(extend_by_pages, bistate->already_extended_by);
302 :
303 : /*
304 : * Can't extend by more than MAX_BUFFERS_TO_EXTEND_BY, we need to pin
305 : * them all concurrently.
306 : */
307 190570 : extend_by_pages = Min(extend_by_pages, MAX_BUFFERS_TO_EXTEND_BY);
308 : }
309 :
310 : /*
311 : * How many of the extended pages should be entered into the FSM?
312 : *
313 : * If we have a bistate, only enter pages that we don't need ourselves
314 : * into the FSM. Otherwise every other backend will immediately try to
315 : * use the pages this backend needs for itself, causing unnecessary
316 : * contention. If we don't have a bistate, we can't avoid the FSM.
317 : *
318 : * Never enter the page returned into the FSM, we'll immediately use it.
319 : */
320 190896 : if (num_pages > 1 && bistate == NULL)
321 506 : not_in_fsm_pages = 1;
322 : else
323 190390 : not_in_fsm_pages = num_pages;
324 :
325 : /* prepare to put another buffer into the bistate */
326 190896 : if (bistate && bistate->current_buf != InvalidBuffer)
327 : {
328 8226 : ReleaseBuffer(bistate->current_buf);
329 8226 : bistate->current_buf = InvalidBuffer;
330 : }
331 :
332 : /*
333 : * Extend the relation. We ask for the first returned page to be locked,
334 : * so that we are sure that nobody has inserted into the page
335 : * concurrently.
336 : *
337 : * With the current MAX_BUFFERS_TO_EXTEND_BY there's no danger of
338 : * [auto]vacuum trying to truncate later pages as REL_TRUNCATE_MINIMUM is
339 : * way larger.
340 : */
341 190896 : first_block = ExtendBufferedRelBy(BMR_REL(relation), MAIN_FORKNUM,
342 : bistate ? bistate->strategy : NULL,
343 : EB_LOCK_FIRST,
344 : extend_by_pages,
345 : victim_buffers,
346 : &extend_by_pages);
347 190896 : buffer = victim_buffers[0]; /* the buffer the function will return */
348 190896 : last_block = first_block + (extend_by_pages - 1);
349 : Assert(first_block == BufferGetBlockNumber(buffer));
350 :
351 : /*
352 : * Relation is now extended. Initialize the page. We do this here, before
353 : * potentially releasing the lock on the page, because it allows us to
354 : * double check that the page contents are empty (this should never
355 : * happen, but if it does we don't want to risk wiping out valid data).
356 : */
357 190896 : page = BufferGetPage(buffer);
358 190896 : if (!PageIsNew(page))
359 0 : elog(ERROR, "page %u of relation \"%s\" should be empty but is not",
360 : first_block,
361 : RelationGetRelationName(relation));
362 :
363 190896 : PageInit(page, BufferGetPageSize(buffer), 0);
364 190896 : MarkBufferDirty(buffer);
365 :
366 : /*
367 : * If we decided to put pages into the FSM, release the buffer lock (but
368 : * not pin), we don't want to do IO while holding a buffer lock. This will
369 : * necessitate a bit more extensive checking in our caller.
370 : */
371 190896 : if (use_fsm && not_in_fsm_pages < extend_by_pages)
372 : {
373 756 : LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
374 756 : *did_unlock = true;
375 : }
376 : else
377 190140 : *did_unlock = false;
378 :
379 : /*
380 : * Relation is now extended. Release pins on all buffers, except for the
381 : * first (which we'll return). If we decided to put pages into the FSM,
382 : * we can do that as part of the same loop.
383 : */
384 224454 : for (uint32 i = 1; i < extend_by_pages; i++)
385 : {
386 33558 : BlockNumber curBlock = first_block + i;
387 :
388 : Assert(curBlock == BufferGetBlockNumber(victim_buffers[i]));
389 : Assert(BlockNumberIsValid(curBlock));
390 :
391 33558 : ReleaseBuffer(victim_buffers[i]);
392 :
393 33558 : if (use_fsm && i >= not_in_fsm_pages)
394 : {
395 10518 : Size freespace = BufferGetPageSize(victim_buffers[i]) -
396 : SizeOfPageHeaderData;
397 :
398 10518 : RecordPageWithFreeSpace(relation, curBlock, freespace);
399 : }
400 : }
401 :
402 190896 : if (use_fsm && not_in_fsm_pages < extend_by_pages)
403 : {
404 756 : BlockNumber first_fsm_block = first_block + not_in_fsm_pages;
405 :
406 756 : FreeSpaceMapVacuumRange(relation, first_fsm_block, last_block);
407 : }
408 :
409 190896 : if (bistate)
410 : {
411 : /*
412 : * Remember the additional pages we extended by, so we later can use
413 : * them without looking into the FSM.
414 : */
415 11426 : if (extend_by_pages > 1)
416 : {
417 1740 : bistate->next_free = first_block + 1;
418 1740 : bistate->last_free = last_block;
419 : }
420 : else
421 : {
422 9686 : bistate->next_free = InvalidBlockNumber;
423 9686 : bistate->last_free = InvalidBlockNumber;
424 : }
425 :
426 : /* maintain bistate->current_buf */
427 11426 : IncrBufferRefCount(buffer);
428 11426 : bistate->current_buf = buffer;
429 11426 : bistate->already_extended_by += extend_by_pages;
430 : }
431 :
432 190896 : return buffer;
433 : #undef MAX_BUFFERS_TO_EXTEND_BY
434 : }
435 :
436 : /*
437 : * RelationGetBufferForTuple
438 : *
439 : * Returns pinned and exclusive-locked buffer of a page in given relation
440 : * with free space >= given len.
441 : *
442 : * If num_pages is > 1, we will try to extend the relation by at least that
443 : * many pages when we decide to extend the relation. This is more efficient
444 : * for callers that know they will need multiple pages
445 : * (e.g. heap_multi_insert()).
446 : *
447 : * If otherBuffer is not InvalidBuffer, then it references a previously
448 : * pinned buffer of another page in the same relation; on return, this
449 : * buffer will also be exclusive-locked. (This case is used by heap_update;
450 : * the otherBuffer contains the tuple being updated.)
451 : *
452 : * The reason for passing otherBuffer is that if two backends are doing
453 : * concurrent heap_update operations, a deadlock could occur if they try
454 : * to lock the same two buffers in opposite orders. To ensure that this
455 : * can't happen, we impose the rule that buffers of a relation must be
456 : * locked in increasing page number order. This is most conveniently done
457 : * by having RelationGetBufferForTuple lock them both, with suitable care
458 : * for ordering.
459 : *
460 : * NOTE: it is unlikely, but not quite impossible, for otherBuffer to be the
461 : * same buffer we select for insertion of the new tuple (this could only
462 : * happen if space is freed in that page after heap_update finds there's not
463 : * enough there). In that case, the page will be pinned and locked only once.
464 : *
465 : * We also handle the possibility that the all-visible flag will need to be
466 : * cleared on one or both pages. If so, pin on the associated visibility map
467 : * page must be acquired before acquiring buffer lock(s), to avoid possibly
468 : * doing I/O while holding buffer locks. The pins are passed back to the
469 : * caller using the input-output arguments vmbuffer and vmbuffer_other.
470 : * Note that in some cases the caller might have already acquired such pins,
471 : * which is indicated by these arguments not being InvalidBuffer on entry.
472 : *
473 : * We normally use FSM to help us find free space. However,
474 : * if HEAP_INSERT_SKIP_FSM is specified, we just append a new empty page to
475 : * the end of the relation if the tuple won't fit on the current target page.
476 : * This can save some cycles when we know the relation is new and doesn't
477 : * contain useful amounts of free space.
478 : *
479 : * HEAP_INSERT_SKIP_FSM is also useful for non-WAL-logged additions to a
480 : * relation, if the caller holds exclusive lock and is careful to invalidate
481 : * relation's smgr_targblock before the first insertion --- that ensures that
482 : * all insertions will occur into newly added pages and not be intermixed
483 : * with tuples from other transactions. That way, a crash can't risk losing
484 : * any committed data of other transactions. (See heap_insert's comments
485 : * for additional constraints needed for safe usage of this behavior.)
486 : *
487 : * The caller can also provide a BulkInsertState object to optimize many
488 : * insertions into the same relation. This keeps a pin on the current
489 : * insertion target page (to save pin/unpin cycles) and also passes a
490 : * BULKWRITE buffer selection strategy object to the buffer manager.
491 : * Passing NULL for bistate selects the default behavior.
492 : *
493 : * We don't fill existing pages further than the fillfactor, except for large
494 : * tuples in nearly-empty pages. This is OK since this routine is not
495 : * consulted when updating a tuple and keeping it on the same page, which is
496 : * the scenario fillfactor is meant to reserve space for.
497 : *
498 : * ereport(ERROR) is allowed here, so this routine *must* be called
499 : * before any (unlogged) changes are made in buffer pool.
500 : */
501 : Buffer
502 16035474 : RelationGetBufferForTuple(Relation relation, Size len,
503 : Buffer otherBuffer, int options,
504 : BulkInsertState bistate,
505 : Buffer *vmbuffer, Buffer *vmbuffer_other,
506 : int num_pages)
507 : {
508 16035474 : bool use_fsm = !(options & HEAP_INSERT_SKIP_FSM);
509 16035474 : Buffer buffer = InvalidBuffer;
510 : Page page;
511 : Size nearlyEmptyFreeSpace,
512 16035474 : pageFreeSpace = 0,
513 16035474 : saveFreeSpace = 0,
514 16035474 : targetFreeSpace = 0;
515 : BlockNumber targetBlock,
516 : otherBlock;
517 : bool unlockedTargetBuffer;
518 : bool recheckVmPins;
519 :
520 16035474 : len = MAXALIGN(len); /* be conservative */
521 :
522 : /* if the caller doesn't know by how many pages to extend, extend by 1 */
523 16035474 : if (num_pages <= 0)
524 15396744 : num_pages = 1;
525 :
526 : /* Bulk insert is not supported for updates, only inserts. */
527 : Assert(otherBuffer == InvalidBuffer || !bistate);
528 :
529 : /*
530 : * If we're gonna fail for oversize tuple, do it right away
531 : */
532 16035474 : if (len > MaxHeapTupleSize)
533 0 : ereport(ERROR,
534 : (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
535 : errmsg("row is too big: size %zu, maximum size %zu",
536 : len, MaxHeapTupleSize)));
537 :
538 : /* Compute desired extra freespace due to fillfactor option */
539 16035474 : saveFreeSpace = RelationGetTargetPageFreeSpace(relation,
540 : HEAP_DEFAULT_FILLFACTOR);
541 :
542 : /*
543 : * Since pages without tuples can still have line pointers, we consider
544 : * pages "empty" when the unavailable space is slight. This threshold is
545 : * somewhat arbitrary, but it should prevent most unnecessary relation
546 : * extensions while inserting large tuples into low-fillfactor tables.
547 : */
548 16035474 : nearlyEmptyFreeSpace = MaxHeapTupleSize -
549 : (MaxHeapTuplesPerPage / 8 * sizeof(ItemIdData));
550 16035474 : if (len + saveFreeSpace > nearlyEmptyFreeSpace)
551 72 : targetFreeSpace = Max(len, nearlyEmptyFreeSpace);
552 : else
553 16035402 : targetFreeSpace = len + saveFreeSpace;
554 :
555 16035474 : if (otherBuffer != InvalidBuffer)
556 281040 : otherBlock = BufferGetBlockNumber(otherBuffer);
557 : else
558 15754434 : otherBlock = InvalidBlockNumber; /* just to keep compiler quiet */
559 :
560 : /*
561 : * We first try to put the tuple on the same page we last inserted a tuple
562 : * on, as cached in the BulkInsertState or relcache entry. If that
563 : * doesn't work, we ask the Free Space Map to locate a suitable page.
564 : * Since the FSM's info might be out of date, we have to be prepared to
565 : * loop around and retry multiple times. (To ensure this isn't an infinite
566 : * loop, we must update the FSM with the correct amount of free space on
567 : * each page that proves not to be suitable.) If the FSM has no record of
568 : * a page with enough free space, we give up and extend the relation.
569 : *
570 : * When use_fsm is false, we either put the tuple onto the existing target
571 : * page or extend the relation.
572 : */
573 16035474 : if (bistate && bistate->current_buf != InvalidBuffer)
574 2236186 : targetBlock = BufferGetBlockNumber(bistate->current_buf);
575 : else
576 13799288 : targetBlock = RelationGetTargetBlock(relation);
577 :
578 16035474 : if (targetBlock == InvalidBlockNumber && use_fsm)
579 : {
580 : /*
581 : * We have no cached target page, so ask the FSM for an initial
582 : * target.
583 : */
584 82534 : targetBlock = GetPageWithFreeSpace(relation, targetFreeSpace);
585 : }
586 :
587 : /*
588 : * If the FSM knows nothing of the rel, try the last page before we give
589 : * up and extend. This avoids one-tuple-per-page syndrome during
590 : * bootstrapping or in a recently-started system.
591 : */
592 16035474 : if (targetBlock == InvalidBlockNumber)
593 : {
594 67380 : BlockNumber nblocks = RelationGetNumberOfBlocks(relation);
595 :
596 67380 : if (nblocks > 0)
597 39662 : targetBlock = nblocks - 1;
598 : }
599 :
600 16035474 : loop:
601 16240692 : while (targetBlock != InvalidBlockNumber)
602 : {
603 : /*
604 : * Read and exclusive-lock the target block, as well as the other
605 : * block if one was given, taking suitable care with lock ordering and
606 : * the possibility they are the same block.
607 : *
608 : * If the page-level all-visible flag is set, caller will need to
609 : * clear both that and the corresponding visibility map bit. However,
610 : * by the time we return, we'll have x-locked the buffer, and we don't
611 : * want to do any I/O while in that state. So we check the bit here
612 : * before taking the lock, and pin the page if it appears necessary.
613 : * Checking without the lock creates a risk of getting the wrong
614 : * answer, so we'll have to recheck after acquiring the lock.
615 : */
616 16055632 : if (otherBuffer == InvalidBuffer)
617 : {
618 : /* easy case */
619 15771638 : buffer = ReadBufferBI(relation, targetBlock, RBM_NORMAL, bistate);
620 15771638 : if (PageIsAllVisible(BufferGetPage(buffer)))
621 19414 : visibilitymap_pin(relation, targetBlock, vmbuffer);
622 :
623 : /*
624 : * If the page is empty, pin vmbuffer to set all_frozen bit later.
625 : */
626 15778732 : if ((options & HEAP_INSERT_FROZEN) &&
627 7094 : (PageGetMaxOffsetNumber(BufferGetPage(buffer)) == 0))
628 3226 : visibilitymap_pin(relation, targetBlock, vmbuffer);
629 :
630 15771638 : LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
631 : }
632 283994 : else if (otherBlock == targetBlock)
633 : {
634 : /* also easy case */
635 2922 : buffer = otherBuffer;
636 2922 : if (PageIsAllVisible(BufferGetPage(buffer)))
637 0 : visibilitymap_pin(relation, targetBlock, vmbuffer);
638 2922 : LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
639 : }
640 281072 : else if (otherBlock < targetBlock)
641 : {
642 : /* lock other buffer first */
643 275306 : buffer = ReadBuffer(relation, targetBlock);
644 275306 : if (PageIsAllVisible(BufferGetPage(buffer)))
645 930 : visibilitymap_pin(relation, targetBlock, vmbuffer);
646 275306 : LockBuffer(otherBuffer, BUFFER_LOCK_EXCLUSIVE);
647 275306 : LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
648 : }
649 : else
650 : {
651 : /* lock target buffer first */
652 5766 : buffer = ReadBuffer(relation, targetBlock);
653 5766 : if (PageIsAllVisible(BufferGetPage(buffer)))
654 92 : visibilitymap_pin(relation, targetBlock, vmbuffer);
655 5766 : LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
656 5766 : LockBuffer(otherBuffer, BUFFER_LOCK_EXCLUSIVE);
657 : }
658 :
659 : /*
660 : * We now have the target page (and the other buffer, if any) pinned
661 : * and locked. However, since our initial PageIsAllVisible checks
662 : * were performed before acquiring the lock, the results might now be
663 : * out of date, either for the selected victim buffer, or for the
664 : * other buffer passed by the caller. In that case, we'll need to
665 : * give up our locks, go get the pin(s) we failed to get earlier, and
666 : * re-lock. That's pretty painful, but hopefully shouldn't happen
667 : * often.
668 : *
669 : * Note that there's a small possibility that we didn't pin the page
670 : * above but still have the correct page pinned anyway, either because
671 : * we've already made a previous pass through this loop, or because
672 : * caller passed us the right page anyway.
673 : *
674 : * Note also that it's possible that by the time we get the pin and
675 : * retake the buffer locks, the visibility map bit will have been
676 : * cleared by some other backend anyway. In that case, we'll have
677 : * done a bit of extra work for no gain, but there's no real harm
678 : * done.
679 : */
680 16055632 : GetVisibilityMapPins(relation, buffer, otherBuffer,
681 : targetBlock, otherBlock, vmbuffer,
682 : vmbuffer_other);
683 :
684 : /*
685 : * Now we can check to see if there's enough free space here. If so,
686 : * we're done.
687 : */
688 16055632 : page = BufferGetPage(buffer);
689 :
690 : /*
691 : * If necessary initialize page, it'll be used soon. We could avoid
692 : * dirtying the buffer here, and rely on the caller to do so whenever
693 : * it puts a tuple onto the page, but there seems not much benefit in
694 : * doing so.
695 : */
696 16055632 : if (PageIsNew(page))
697 : {
698 27190 : PageInit(page, BufferGetPageSize(buffer), 0);
699 27190 : MarkBufferDirty(buffer);
700 : }
701 :
702 16055632 : pageFreeSpace = PageGetHeapFreeSpace(page);
703 16055632 : if (targetFreeSpace <= pageFreeSpace)
704 : {
705 : /* use this page as future insert target, too */
706 15844578 : RelationSetTargetBlock(relation, targetBlock);
707 15844578 : return buffer;
708 : }
709 :
710 : /*
711 : * Not enough space, so we must give up our page locks and pin (if
712 : * any) and prepare to look elsewhere. We don't care which order we
713 : * unlock the two buffers in, so this can be slightly simpler than the
714 : * code above.
715 : */
716 211054 : LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
717 211054 : if (otherBuffer == InvalidBuffer)
718 202138 : ReleaseBuffer(buffer);
719 8916 : else if (otherBlock != targetBlock)
720 : {
721 5994 : LockBuffer(otherBuffer, BUFFER_LOCK_UNLOCK);
722 5994 : ReleaseBuffer(buffer);
723 : }
724 :
725 : /* Is there an ongoing bulk extension? */
726 211054 : if (bistate && bistate->next_free != InvalidBlockNumber)
727 : {
728 : Assert(bistate->next_free <= bistate->last_free);
729 :
730 : /*
731 : * We bulk extended the relation before, and there are still some
732 : * unused pages from that extension, so we don't need to look in
733 : * the FSM for a new page. But do record the free space from the
734 : * last page, somebody might insert narrower tuples later.
735 : */
736 23970 : if (use_fsm)
737 8580 : RecordPageWithFreeSpace(relation, targetBlock, pageFreeSpace);
738 :
739 23970 : targetBlock = bistate->next_free;
740 23970 : if (bistate->next_free >= bistate->last_free)
741 : {
742 1390 : bistate->next_free = InvalidBlockNumber;
743 1390 : bistate->last_free = InvalidBlockNumber;
744 : }
745 : else
746 22580 : bistate->next_free++;
747 : }
748 187084 : else if (!use_fsm)
749 : {
750 : /* Without FSM, always fall out of the loop and extend */
751 5836 : break;
752 : }
753 : else
754 : {
755 : /*
756 : * Update FSM as to condition of this page, and ask for another
757 : * page to try.
758 : */
759 181248 : targetBlock = RecordAndGetPageWithFreeSpace(relation,
760 : targetBlock,
761 : pageFreeSpace,
762 : targetFreeSpace);
763 : }
764 : }
765 :
766 : /* Have to extend the relation */
767 190896 : buffer = RelationAddBlocks(relation, bistate, num_pages, use_fsm,
768 : &unlockedTargetBuffer);
769 :
770 190896 : targetBlock = BufferGetBlockNumber(buffer);
771 190896 : page = BufferGetPage(buffer);
772 :
773 : /*
774 : * The page is empty, pin vmbuffer to set all_frozen bit. We don't want to
775 : * do IO while the buffer is locked, so we unlock the page first if IO is
776 : * needed (necessitating checks below).
777 : */
778 190896 : if (options & HEAP_INSERT_FROZEN)
779 : {
780 : Assert(PageGetMaxOffsetNumber(page) == 0);
781 :
782 298 : if (!visibilitymap_pin_ok(targetBlock, *vmbuffer))
783 : {
784 244 : if (!unlockedTargetBuffer)
785 244 : LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
786 244 : unlockedTargetBuffer = true;
787 244 : visibilitymap_pin(relation, targetBlock, vmbuffer);
788 : }
789 : }
790 :
791 : /*
792 : * Reacquire locks if necessary.
793 : *
794 : * If the target buffer was unlocked above, or is unlocked while
795 : * reacquiring the lock on otherBuffer below, it's unlikely, but possible,
796 : * that another backend used space on this page. We check for that below,
797 : * and retry if necessary.
798 : */
799 190896 : recheckVmPins = false;
800 190896 : if (unlockedTargetBuffer)
801 : {
802 : /* released lock on target buffer above */
803 1000 : if (otherBuffer != InvalidBuffer)
804 0 : LockBuffer(otherBuffer, BUFFER_LOCK_EXCLUSIVE);
805 1000 : LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
806 1000 : recheckVmPins = true;
807 : }
808 189896 : else if (otherBuffer != InvalidBuffer)
809 : {
810 : /*
811 : * We did not release the target buffer, and otherBuffer is valid,
812 : * need to lock the other buffer. It's guaranteed to be of a lower
813 : * page number than the new page. To conform with the deadlock
814 : * prevent rules, we ought to lock otherBuffer first, but that would
815 : * give other backends a chance to put tuples on our page. To reduce
816 : * the likelihood of that, attempt to lock the other buffer
817 : * conditionally, that's very likely to work.
818 : *
819 : * Alternatively, we could acquire the lock on otherBuffer before
820 : * extending the relation, but that'd require holding the lock while
821 : * performing IO, which seems worse than an unlikely retry.
822 : */
823 : Assert(otherBuffer != buffer);
824 : Assert(targetBlock > otherBlock);
825 :
826 5962 : if (unlikely(!ConditionalLockBuffer(otherBuffer)))
827 : {
828 0 : unlockedTargetBuffer = true;
829 0 : LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
830 0 : LockBuffer(otherBuffer, BUFFER_LOCK_EXCLUSIVE);
831 0 : LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
832 : }
833 5962 : recheckVmPins = true;
834 : }
835 :
836 : /*
837 : * If one of the buffers was unlocked (always the case if otherBuffer is
838 : * valid), it's possible, although unlikely, that an all-visible flag
839 : * became set. We can use GetVisibilityMapPins to deal with that. It's
840 : * possible that GetVisibilityMapPins() might need to temporarily release
841 : * buffer locks, in which case we'll need to check if there's still enough
842 : * space on the page below.
843 : */
844 190896 : if (recheckVmPins)
845 : {
846 6962 : if (GetVisibilityMapPins(relation, otherBuffer, buffer,
847 : otherBlock, targetBlock, vmbuffer_other,
848 : vmbuffer))
849 0 : unlockedTargetBuffer = true;
850 : }
851 :
852 : /*
853 : * If the target buffer was temporarily unlocked since the relation
854 : * extension, it's possible, although unlikely, that all the space on the
855 : * page was already used. If so, we just retry from the start. If we
856 : * didn't unlock, something has gone wrong if there's not enough space -
857 : * the test at the top should have prevented reaching this case.
858 : */
859 190896 : pageFreeSpace = PageGetHeapFreeSpace(page);
860 190896 : if (len > pageFreeSpace)
861 : {
862 0 : if (unlockedTargetBuffer)
863 : {
864 0 : if (otherBuffer != InvalidBuffer)
865 0 : LockBuffer(otherBuffer, BUFFER_LOCK_UNLOCK);
866 0 : UnlockReleaseBuffer(buffer);
867 :
868 0 : goto loop;
869 : }
870 0 : elog(PANIC, "tuple is too big: size %zu", len);
871 : }
872 :
873 : /*
874 : * Remember the new page as our target for future insertions.
875 : *
876 : * XXX should we enter the new page into the free space map immediately,
877 : * or just keep it for this backend's exclusive use in the short run
878 : * (until VACUUM sees it)? Seems to depend on whether you expect the
879 : * current backend to make more insertions or not, which is probably a
880 : * good bet most of the time. So for now, don't add it to FSM yet.
881 : */
882 190896 : RelationSetTargetBlock(relation, targetBlock);
883 :
884 190896 : return buffer;
885 : }
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