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1 : : /*-------------------------------------------------------------------------
2 : : *
3 : : * bufpage.c
4 : : * POSTGRES standard buffer page code.
5 : : *
6 : : * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group
7 : : * Portions Copyright (c) 1994, Regents of the University of California
8 : : *
9 : : *
10 : : * IDENTIFICATION
11 : : * src/backend/storage/page/bufpage.c
12 : : *
13 : : *-------------------------------------------------------------------------
14 : : */
15 : : #include "postgres.h"
16 : :
17 : : #include "access/htup_details.h"
18 : : #include "access/itup.h"
19 : : #include "access/xlog.h"
20 : : #include "pgstat.h"
21 : : #include "storage/checksum.h"
22 : : #include "utils/memdebug.h"
23 : : #include "utils/memutils.h"
24 : :
25 : :
26 : : /* GUC variable */
27 : : bool ignore_checksum_failure = false;
28 : :
29 : :
30 : : /* ----------------------------------------------------------------
31 : : * Page support functions
32 : : * ----------------------------------------------------------------
33 : : */
34 : :
35 : : /*
36 : : * PageInit
37 : : * Initializes the contents of a page.
38 : : * Note that we don't calculate an initial checksum here; that's not done
39 : : * until it's time to write.
40 : : */
41 : : void
42 : 436158 : PageInit(Page page, Size pageSize, Size specialSize)
43 : : {
44 : 436158 : PageHeader p = (PageHeader) page;
45 : :
46 : 436158 : specialSize = MAXALIGN(specialSize);
47 : :
48 : : Assert(pageSize == BLCKSZ);
49 : : Assert(pageSize > specialSize + SizeOfPageHeaderData);
50 : :
51 : : /* Make sure all fields of page are zero, as well as unused space */
52 [ + - + - : 436158 : MemSet(p, 0, pageSize);
+ - - + -
- ]
53 : :
54 : 436158 : p->pd_flags = 0;
55 : 436158 : p->pd_lower = SizeOfPageHeaderData;
56 : 436158 : p->pd_upper = pageSize - specialSize;
57 : 436158 : p->pd_special = pageSize - specialSize;
58 : 436158 : PageSetPageSizeAndVersion(page, pageSize, PG_PAGE_LAYOUT_VERSION);
59 : : /* p->pd_prune_xid = InvalidTransactionId; done by above MemSet */
60 : 436158 : }
61 : :
62 : :
63 : : /*
64 : : * PageIsVerified
65 : : * Check that the page header and checksum (if any) appear valid.
66 : : *
67 : : * This is called when a page has just been read in from disk. The idea is
68 : : * to cheaply detect trashed pages before we go nuts following bogus line
69 : : * pointers, testing invalid transaction identifiers, etc.
70 : : *
71 : : * It turns out to be necessary to allow zeroed pages here too. Even though
72 : : * this routine is *not* called when deliberately adding a page to a relation,
73 : : * there are scenarios in which a zeroed page might be found in a table.
74 : : * (Example: a backend extends a relation, then crashes before it can write
75 : : * any WAL entry about the new page. The kernel will already have the
76 : : * zeroed page in the file, and it will stay that way after restart.) So we
77 : : * allow zeroed pages here, and are careful that the page access macros
78 : : * treat such a page as empty and without free space. Eventually, VACUUM
79 : : * will clean up such a page and make it usable.
80 : : *
81 : : * If flag PIV_LOG_WARNING/PIV_LOG_LOG is set, a WARNING/LOG message is logged
82 : : * in the event of a checksum failure.
83 : : *
84 : : * If flag PIV_IGNORE_CHECKSUM_FAILURE is set, checksum failures will cause a
85 : : * message about the failure to be emitted, but will not cause
86 : : * PageIsVerified() to return false.
87 : : *
88 : : * To allow the caller to report statistics about checksum failures,
89 : : * *checksum_failure_p can be passed in. Note that there may be checksum
90 : : * failures even if this function returns true, due to
91 : : * PIV_IGNORE_CHECKSUM_FAILURE.
92 : : */
93 : : bool
94 : 1521015 : PageIsVerified(PageData *page, BlockNumber blkno, int flags, bool *checksum_failure_p)
95 : : {
96 : 1521015 : const PageHeaderData *p = (const PageHeaderData *) page;
97 : : size_t *pagebytes;
98 : 1521015 : bool checksum_failure = false;
99 : 1521015 : bool header_sane = false;
100 : 1521015 : uint16 checksum = 0;
101 : :
102 [ + - ]: 1521015 : if (checksum_failure_p)
103 : 1521015 : *checksum_failure_p = false;
104 : :
105 : : /*
106 : : * Don't verify page data unless the page passes basic non-zero test
107 : : */
108 [ + + ]: 1521015 : if (!PageIsNew(page))
109 : : {
110 : : /*
111 : : * There shouldn't be any check for interrupt calls happening in this
112 : : * codepath, but just to be on the safe side we hold interrupts since
113 : : * if they did happen the data checksum state could change during
114 : : * verifying checksums, which could lead to incorrect verification
115 : : * results.
116 : : */
117 : 1516417 : HOLD_INTERRUPTS();
118 [ + + ]: 1516417 : if (DataChecksumsNeedVerify())
119 : : {
120 : 1423580 : checksum = pg_checksum_page(page, blkno);
121 : :
122 [ + + ]: 1423580 : if (checksum != p->pd_checksum)
123 : : {
124 : 32 : checksum_failure = true;
125 [ + - ]: 32 : if (checksum_failure_p)
126 : 32 : *checksum_failure_p = true;
127 : : }
128 : : }
129 : 1516417 : RESUME_INTERRUPTS();
130 : :
131 : : /*
132 : : * The following checks don't prove the header is correct, only that
133 : : * it looks sane enough to allow into the buffer pool. Later usage of
134 : : * the block can still reveal problems, which is why we offer the
135 : : * checksum option.
136 : : */
137 [ + - ]: 1516417 : if ((p->pd_flags & ~PD_VALID_FLAG_BITS) == 0 &&
138 [ + - ]: 1516417 : p->pd_lower <= p->pd_upper &&
139 [ + - ]: 1516417 : p->pd_upper <= p->pd_special &&
140 [ + + ]: 1516417 : p->pd_special <= BLCKSZ &&
141 [ + - ]: 1516335 : p->pd_special == MAXALIGN(p->pd_special))
142 : 1516335 : header_sane = true;
143 : :
144 [ + + + + ]: 1516417 : if (header_sane && !checksum_failure)
145 : 1516309 : return true;
146 : : }
147 : :
148 : : /* Check all-zeroes case */
149 : 4706 : pagebytes = (size_t *) page;
150 : :
151 [ + + ]: 4706 : if (pg_memory_is_all_zeros(pagebytes, BLCKSZ))
152 : 4598 : return true;
153 : :
154 : : /*
155 : : * Throw a WARNING/LOG, as instructed by PIV_LOG_*, if the checksum fails,
156 : : * but only after we've checked for the all-zeroes case.
157 : : */
158 [ + + ]: 108 : if (checksum_failure)
159 : : {
160 [ + - ]: 32 : if ((flags & (PIV_LOG_WARNING | PIV_LOG_LOG)) != 0)
161 [ - + + - : 32 : ereport(flags & PIV_LOG_WARNING ? WARNING : LOG,
+ + ]
162 : : (errcode(ERRCODE_DATA_CORRUPTED),
163 : : errmsg("page verification failed, calculated checksum %u but expected %u%s",
164 : : checksum, p->pd_checksum,
165 : : (flags & PIV_ZERO_BUFFERS_ON_ERROR ? ", buffer will be zeroed" : ""))));
166 : :
167 [ + + + + ]: 32 : if (header_sane && (flags & PIV_IGNORE_CHECKSUM_FAILURE))
168 : 12 : return true;
169 : : }
170 : :
171 : 96 : return false;
172 : : }
173 : :
174 : :
175 : : /*
176 : : * PageAddItemExtended
177 : : *
178 : : * Add an item to a page. Return value is the offset at which it was
179 : : * inserted, or InvalidOffsetNumber if the item is not inserted for any
180 : : * reason. A WARNING is issued indicating the reason for the refusal.
181 : : *
182 : : * offsetNumber must be either InvalidOffsetNumber to specify finding a
183 : : * free line pointer, or a value between FirstOffsetNumber and one past
184 : : * the last existing item, to specify using that particular line pointer.
185 : : *
186 : : * If offsetNumber is valid and flag PAI_OVERWRITE is set, we just store
187 : : * the item at the specified offsetNumber, which must be either a
188 : : * currently-unused line pointer, or one past the last existing item.
189 : : *
190 : : * If offsetNumber is valid and flag PAI_OVERWRITE is not set, insert
191 : : * the item at the specified offsetNumber, moving existing items later
192 : : * in the array to make room.
193 : : *
194 : : * If offsetNumber is not valid, then assign a slot by finding the first
195 : : * one that is both unused and deallocated.
196 : : *
197 : : * If flag PAI_IS_HEAP is set, we enforce that there can't be more than
198 : : * MaxHeapTuplesPerPage line pointers on the page.
199 : : *
200 : : * !!! EREPORT(ERROR) IS DISALLOWED HERE !!!
201 : : */
202 : : OffsetNumber
203 : 47189319 : PageAddItemExtended(Page page,
204 : : const void *item,
205 : : Size size,
206 : : OffsetNumber offsetNumber,
207 : : int flags)
208 : : {
209 : 47189319 : PageHeader phdr = (PageHeader) page;
210 : : Size alignedSize;
211 : : int lower;
212 : : int upper;
213 : : ItemId itemId;
214 : : OffsetNumber limit;
215 : 47189319 : bool needshuffle = false;
216 : :
217 : : /*
218 : : * Be wary about corrupted page pointers
219 : : */
220 [ + - ]: 47189319 : if (phdr->pd_lower < SizeOfPageHeaderData ||
221 [ + - ]: 47189319 : phdr->pd_lower > phdr->pd_upper ||
222 [ + - ]: 47189319 : phdr->pd_upper > phdr->pd_special ||
223 [ - + ]: 47189319 : phdr->pd_special > BLCKSZ)
224 [ # # ]: 0 : ereport(PANIC,
225 : : (errcode(ERRCODE_DATA_CORRUPTED),
226 : : errmsg("corrupted page pointers: lower = %u, upper = %u, special = %u",
227 : : phdr->pd_lower, phdr->pd_upper, phdr->pd_special)));
228 : :
229 : : /*
230 : : * Select offsetNumber to place the new item at
231 : : */
232 : 47189319 : limit = OffsetNumberNext(PageGetMaxOffsetNumber(page));
233 : :
234 : : /* was offsetNumber passed in? */
235 [ + + + - : 47189319 : if (OffsetNumberIsValid(offsetNumber))
+ + ]
236 : : {
237 : : /* yes, check it */
238 [ + + ]: 29355334 : if ((flags & PAI_OVERWRITE) != 0)
239 : : {
240 [ + + ]: 1642896 : if (offsetNumber < limit)
241 : : {
242 : 33865 : itemId = PageGetItemId(page, offsetNumber);
243 [ + - - + ]: 33865 : if (ItemIdIsUsed(itemId) || ItemIdHasStorage(itemId))
244 : : {
245 [ # # ]: 0 : elog(WARNING, "will not overwrite a used ItemId");
246 : 0 : return InvalidOffsetNumber;
247 : : }
248 : : }
249 : : }
250 : : else
251 : : {
252 [ + + ]: 27712438 : if (offsetNumber < limit)
253 : 4243540 : needshuffle = true; /* need to move existing linp's */
254 : : }
255 : : }
256 : : else
257 : : {
258 : : /* offsetNumber was not passed in, so find a free slot */
259 : : /* if no free slot, we'll put it at limit (1st open slot) */
260 [ + + ]: 17833985 : if (PageHasFreeLinePointers(page))
261 : : {
262 : : /*
263 : : * Scan line pointer array to locate a "recyclable" (unused)
264 : : * ItemId.
265 : : *
266 : : * Always use earlier items first. PageTruncateLinePointerArray
267 : : * can only truncate unused items when they appear as a contiguous
268 : : * group at the end of the line pointer array.
269 : : */
270 : 186894 : for (offsetNumber = FirstOffsetNumber;
271 [ + + ]: 11203174 : offsetNumber < limit; /* limit is maxoff+1 */
272 : 11016280 : offsetNumber++)
273 : : {
274 : 11192060 : itemId = PageGetItemId(page, offsetNumber);
275 : :
276 : : /*
277 : : * We check for no storage as well, just to be paranoid;
278 : : * unused items should never have storage. Assert() that the
279 : : * invariant is respected too.
280 : : */
281 : : Assert(ItemIdIsUsed(itemId) || !ItemIdHasStorage(itemId));
282 : :
283 [ + + + - ]: 11192060 : if (!ItemIdIsUsed(itemId) && !ItemIdHasStorage(itemId))
284 : 175780 : break;
285 : : }
286 [ + + ]: 186894 : if (offsetNumber >= limit)
287 : : {
288 : : /* the hint is wrong, so reset it */
289 : 11114 : PageClearHasFreeLinePointers(page);
290 : : }
291 : : }
292 : : else
293 : : {
294 : : /* don't bother searching if hint says there's no free slot */
295 : 17647091 : offsetNumber = limit;
296 : : }
297 : : }
298 : :
299 : : /* Reject placing items beyond the first unused line pointer */
300 [ - + ]: 47189319 : if (offsetNumber > limit)
301 : : {
302 [ # # ]: 0 : elog(WARNING, "specified item offset is too large");
303 : 0 : return InvalidOffsetNumber;
304 : : }
305 : :
306 : : /* Reject placing items beyond heap boundary, if heap */
307 [ + + - + ]: 47189319 : if ((flags & PAI_IS_HEAP) != 0 && offsetNumber > MaxHeapTuplesPerPage)
308 : : {
309 [ # # ]: 0 : elog(WARNING, "can't put more than MaxHeapTuplesPerPage items in a heap page");
310 : 0 : return InvalidOffsetNumber;
311 : : }
312 : :
313 : : /*
314 : : * Compute new lower and upper pointers for page, see if it'll fit.
315 : : *
316 : : * Note: do arithmetic as signed ints, to avoid mistakes if, say,
317 : : * alignedSize > pd_upper.
318 : : */
319 [ + + + + ]: 47189319 : if (offsetNumber == limit || needshuffle)
320 : 46979674 : lower = phdr->pd_lower + sizeof(ItemIdData);
321 : : else
322 : 209645 : lower = phdr->pd_lower;
323 : :
324 : 47189319 : alignedSize = MAXALIGN(size);
325 : :
326 : 47189319 : upper = (int) phdr->pd_upper - (int) alignedSize;
327 : :
328 [ - + ]: 47189319 : if (lower > upper)
329 : 0 : return InvalidOffsetNumber;
330 : :
331 : : /*
332 : : * OK to insert the item. First, shuffle the existing pointers if needed.
333 : : */
334 : 47189319 : itemId = PageGetItemId(page, offsetNumber);
335 : :
336 [ + + ]: 47189319 : if (needshuffle)
337 : 4243540 : memmove(itemId + 1, itemId,
338 : 4243540 : (limit - offsetNumber) * sizeof(ItemIdData));
339 : :
340 : : /* set the line pointer */
341 : 47189319 : ItemIdSetNormal(itemId, upper, size);
342 : :
343 : : /*
344 : : * Items normally contain no uninitialized bytes. Core bufpage consumers
345 : : * conform, but this is not a necessary coding rule; a new index AM could
346 : : * opt to depart from it. However, data type input functions and other
347 : : * C-language functions that synthesize datums should initialize all
348 : : * bytes; datumIsEqual() relies on this. Testing here, along with the
349 : : * similar check in printtup(), helps to catch such mistakes.
350 : : *
351 : : * Values of the "name" type retrieved via index-only scans may contain
352 : : * uninitialized bytes; see comment in btrescan(). Valgrind will report
353 : : * this as an error, but it is safe to ignore.
354 : : */
355 : : VALGRIND_CHECK_MEM_IS_DEFINED(item, size);
356 : :
357 : : /* copy the item's data onto the page */
358 : 47189319 : memcpy((char *) page + upper, item, size);
359 : :
360 : : /* adjust page header */
361 : 47189319 : phdr->pd_lower = (LocationIndex) lower;
362 : 47189319 : phdr->pd_upper = (LocationIndex) upper;
363 : :
364 : 47189319 : return offsetNumber;
365 : : }
366 : :
367 : :
368 : : /*
369 : : * PageGetTempPage
370 : : * Get a temporary page in local memory for special processing.
371 : : * The returned page is not initialized at all; caller must do that.
372 : : */
373 : : Page
374 : 135 : PageGetTempPage(const PageData *page)
375 : : {
376 : : Size pageSize;
377 : : Page temp;
378 : :
379 : 135 : pageSize = PageGetPageSize(page);
380 : 135 : temp = (Page) palloc(pageSize);
381 : :
382 : 135 : return temp;
383 : : }
384 : :
385 : : /*
386 : : * PageGetTempPageCopy
387 : : * Get a temporary page in local memory for special processing.
388 : : * The page is initialized by copying the contents of the given page.
389 : : */
390 : : Page
391 : 7227 : PageGetTempPageCopy(const PageData *page)
392 : : {
393 : : Size pageSize;
394 : : Page temp;
395 : :
396 : 7227 : pageSize = PageGetPageSize(page);
397 : 7227 : temp = (Page) palloc(pageSize);
398 : :
399 : 7227 : memcpy(temp, page, pageSize);
400 : :
401 : 7227 : return temp;
402 : : }
403 : :
404 : : /*
405 : : * PageGetTempPageCopySpecial
406 : : * Get a temporary page in local memory for special processing.
407 : : * The page is PageInit'd with the same special-space size as the
408 : : * given page, and the special space is copied from the given page.
409 : : */
410 : : Page
411 : 38359 : PageGetTempPageCopySpecial(const PageData *page)
412 : : {
413 : : Size pageSize;
414 : : Page temp;
415 : :
416 : 38359 : pageSize = PageGetPageSize(page);
417 : 38359 : temp = (Page) palloc(pageSize);
418 : :
419 : 38359 : PageInit(temp, pageSize, PageGetSpecialSize(page));
420 : 115077 : memcpy(PageGetSpecialPointer(temp),
421 : 38359 : PageGetSpecialPointer(page),
422 : 38359 : PageGetSpecialSize(page));
423 : :
424 : 38359 : return temp;
425 : : }
426 : :
427 : : /*
428 : : * PageRestoreTempPage
429 : : * Copy temporary page back to permanent page after special processing
430 : : * and release the temporary page.
431 : : */
432 : : void
433 : 36035 : PageRestoreTempPage(Page tempPage, Page oldPage)
434 : : {
435 : : Size pageSize;
436 : :
437 : 36035 : pageSize = PageGetPageSize(tempPage);
438 : 36035 : memcpy(oldPage, tempPage, pageSize);
439 : :
440 : 36035 : pfree(tempPage);
441 : 36035 : }
442 : :
443 : : /*
444 : : * Tuple defrag support for PageRepairFragmentation and PageIndexMultiDelete
445 : : */
446 : : typedef struct itemIdCompactData
447 : : {
448 : : uint16 offsetindex; /* linp array index */
449 : : int16 itemoff; /* page offset of item data */
450 : : uint16 alignedlen; /* MAXALIGN(item data len) */
451 : : } itemIdCompactData;
452 : : typedef itemIdCompactData *itemIdCompact;
453 : :
454 : : /*
455 : : * After removing or marking some line pointers unused, move the tuples to
456 : : * remove the gaps caused by the removed items and reorder them back into
457 : : * reverse line pointer order in the page.
458 : : *
459 : : * This function can often be fairly hot, so it pays to take some measures to
460 : : * make it as optimal as possible.
461 : : *
462 : : * Callers may pass 'presorted' as true if the 'itemidbase' array is sorted in
463 : : * descending order of itemoff. When this is true we can just memmove()
464 : : * tuples towards the end of the page. This is quite a common case as it's
465 : : * the order that tuples are initially inserted into pages. When we call this
466 : : * function to defragment the tuples in the page then any new line pointers
467 : : * added to the page will keep that presorted order, so hitting this case is
468 : : * still very common for tables that are commonly updated.
469 : : *
470 : : * When the 'itemidbase' array is not presorted then we're unable to just
471 : : * memmove() tuples around freely. Doing so could cause us to overwrite the
472 : : * memory belonging to a tuple we've not moved yet. In this case, we copy all
473 : : * the tuples that need to be moved into a temporary buffer. We can then
474 : : * simply memcpy() out of that temp buffer back into the page at the correct
475 : : * location. Tuples are copied back into the page in the same order as the
476 : : * 'itemidbase' array, so we end up reordering the tuples back into reverse
477 : : * line pointer order. This will increase the chances of hitting the
478 : : * presorted case the next time around.
479 : : *
480 : : * Callers must ensure that nitems is > 0
481 : : */
482 : : static void
483 : 79912 : compactify_tuples(itemIdCompact itemidbase, int nitems, Page page, bool presorted)
484 : : {
485 : 79912 : PageHeader phdr = (PageHeader) page;
486 : : Offset upper;
487 : : Offset copy_tail;
488 : : Offset copy_head;
489 : : itemIdCompact itemidptr;
490 : : int i;
491 : :
492 : : /* Code within will not work correctly if nitems == 0 */
493 : : Assert(nitems > 0);
494 : :
495 [ + + ]: 79912 : if (presorted)
496 : : {
497 : :
498 : : #ifdef USE_ASSERT_CHECKING
499 : : {
500 : : /*
501 : : * Verify we've not gotten any new callers that are incorrectly
502 : : * passing a true presorted value.
503 : : */
504 : : Offset lastoff = phdr->pd_special;
505 : :
506 : : for (i = 0; i < nitems; i++)
507 : : {
508 : : itemidptr = &itemidbase[i];
509 : :
510 : : Assert(lastoff > itemidptr->itemoff);
511 : :
512 : : lastoff = itemidptr->itemoff;
513 : : }
514 : : }
515 : : #endif /* USE_ASSERT_CHECKING */
516 : :
517 : : /*
518 : : * 'itemidbase' is already in the optimal order, i.e, lower item
519 : : * pointers have a higher offset. This allows us to memmove() the
520 : : * tuples up to the end of the page without having to worry about
521 : : * overwriting other tuples that have not been moved yet.
522 : : *
523 : : * There's a good chance that there are tuples already right at the
524 : : * end of the page that we can simply skip over because they're
525 : : * already in the correct location within the page. We'll do that
526 : : * first...
527 : : */
528 : 58383 : upper = phdr->pd_special;
529 : 58383 : i = 0;
530 : : do
531 : : {
532 : 869874 : itemidptr = &itemidbase[i];
533 [ + + ]: 869874 : if (upper != itemidptr->itemoff + itemidptr->alignedlen)
534 : 51692 : break;
535 : 818182 : upper -= itemidptr->alignedlen;
536 : :
537 : 818182 : i++;
538 [ + + ]: 818182 : } while (i < nitems);
539 : :
540 : : /*
541 : : * Now that we've found the first tuple that needs to be moved, we can
542 : : * do the tuple compactification. We try and make the least number of
543 : : * memmove() calls and only call memmove() when there's a gap. When
544 : : * we see a gap we just move all tuples after the gap up until the
545 : : * point of the last move operation.
546 : : */
547 : 58383 : copy_tail = copy_head = itemidptr->itemoff + itemidptr->alignedlen;
548 [ + + ]: 1328003 : for (; i < nitems; i++)
549 : : {
550 : : ItemId lp;
551 : :
552 : 1269620 : itemidptr = &itemidbase[i];
553 : 1269620 : lp = PageGetItemId(page, itemidptr->offsetindex + 1);
554 : :
555 [ + + ]: 1269620 : if (copy_head != itemidptr->itemoff + itemidptr->alignedlen)
556 : : {
557 : 151165 : memmove((char *) page + upper,
558 : 151165 : page + copy_head,
559 : 151165 : copy_tail - copy_head);
560 : :
561 : : /*
562 : : * We've now moved all tuples already seen, but not the
563 : : * current tuple, so we set the copy_tail to the end of this
564 : : * tuple so it can be moved in another iteration of the loop.
565 : : */
566 : 151165 : copy_tail = itemidptr->itemoff + itemidptr->alignedlen;
567 : : }
568 : : /* shift the target offset down by the length of this tuple */
569 : 1269620 : upper -= itemidptr->alignedlen;
570 : : /* point the copy_head to the start of this tuple */
571 : 1269620 : copy_head = itemidptr->itemoff;
572 : :
573 : : /* update the line pointer to reference the new offset */
574 : 1269620 : lp->lp_off = upper;
575 : : }
576 : :
577 : : /* move the remaining tuples. */
578 : 58383 : memmove((char *) page + upper,
579 : 58383 : page + copy_head,
580 : 58383 : copy_tail - copy_head);
581 : : }
582 : : else
583 : : {
584 : : PGAlignedBlock scratch;
585 : 21529 : char *scratchptr = scratch.data;
586 : :
587 : : /*
588 : : * Non-presorted case: The tuples in the itemidbase array may be in
589 : : * any order. So, in order to move these to the end of the page we
590 : : * must make a temp copy of each tuple that needs to be moved before
591 : : * we copy them back into the page at the new offset.
592 : : *
593 : : * If a large percentage of tuples have been pruned (>75%) then we'll
594 : : * copy these into the temp buffer tuple-by-tuple, otherwise, we'll
595 : : * just do a single memcpy() for all tuples that need to be moved.
596 : : * When so many tuples have been removed there's likely to be a lot of
597 : : * gaps and it's unlikely that many non-movable tuples remain at the
598 : : * end of the page.
599 : : */
600 [ + + ]: 21529 : if (nitems < PageGetMaxOffsetNumber(page) / 4)
601 : : {
602 : 1187 : i = 0;
603 : : do
604 : : {
605 : 25007 : itemidptr = &itemidbase[i];
606 : 25007 : memcpy(scratchptr + itemidptr->itemoff, page + itemidptr->itemoff,
607 : 25007 : itemidptr->alignedlen);
608 : 25007 : i++;
609 [ + + ]: 25007 : } while (i < nitems);
610 : :
611 : : /* Set things up for the compactification code below */
612 : 1187 : i = 0;
613 : 1187 : itemidptr = &itemidbase[0];
614 : 1187 : upper = phdr->pd_special;
615 : : }
616 : : else
617 : : {
618 : 20342 : upper = phdr->pd_special;
619 : :
620 : : /*
621 : : * Many tuples are likely to already be in the correct location.
622 : : * There's no need to copy these into the temp buffer. Instead
623 : : * we'll just skip forward in the itemidbase array to the position
624 : : * that we do need to move tuples from so that the code below just
625 : : * leaves these ones alone.
626 : : */
627 : 20342 : i = 0;
628 : : do
629 : : {
630 : 502036 : itemidptr = &itemidbase[i];
631 [ + + ]: 502036 : if (upper != itemidptr->itemoff + itemidptr->alignedlen)
632 : 20342 : break;
633 : 481694 : upper -= itemidptr->alignedlen;
634 : :
635 : 481694 : i++;
636 [ + - ]: 481694 : } while (i < nitems);
637 : :
638 : : /* Copy all tuples that need to be moved into the temp buffer */
639 : 20342 : memcpy(scratchptr + phdr->pd_upper,
640 : 20342 : page + phdr->pd_upper,
641 : 20342 : upper - phdr->pd_upper);
642 : : }
643 : :
644 : : /*
645 : : * Do the tuple compactification. itemidptr is already pointing to
646 : : * the first tuple that we're going to move. Here we collapse the
647 : : * memcpy calls for adjacent tuples into a single call. This is done
648 : : * by delaying the memcpy call until we find a gap that needs to be
649 : : * closed.
650 : : */
651 : 21529 : copy_tail = copy_head = itemidptr->itemoff + itemidptr->alignedlen;
652 [ + + ]: 2271267 : for (; i < nitems; i++)
653 : : {
654 : : ItemId lp;
655 : :
656 : 2249738 : itemidptr = &itemidbase[i];
657 : 2249738 : lp = PageGetItemId(page, itemidptr->offsetindex + 1);
658 : :
659 : : /* copy pending tuples when we detect a gap */
660 [ + + ]: 2249738 : if (copy_head != itemidptr->itemoff + itemidptr->alignedlen)
661 : : {
662 : 607709 : memcpy((char *) page + upper,
663 : 607709 : scratchptr + copy_head,
664 : 607709 : copy_tail - copy_head);
665 : :
666 : : /*
667 : : * We've now copied all tuples already seen, but not the
668 : : * current tuple, so we set the copy_tail to the end of this
669 : : * tuple.
670 : : */
671 : 607709 : copy_tail = itemidptr->itemoff + itemidptr->alignedlen;
672 : : }
673 : : /* shift the target offset down by the length of this tuple */
674 : 2249738 : upper -= itemidptr->alignedlen;
675 : : /* point the copy_head to the start of this tuple */
676 : 2249738 : copy_head = itemidptr->itemoff;
677 : :
678 : : /* update the line pointer to reference the new offset */
679 : 2249738 : lp->lp_off = upper;
680 : : }
681 : :
682 : : /* Copy the remaining chunk */
683 : 21529 : memcpy((char *) page + upper,
684 : 21529 : scratchptr + copy_head,
685 : 21529 : copy_tail - copy_head);
686 : : }
687 : :
688 : 79912 : phdr->pd_upper = upper;
689 : 79912 : }
690 : :
691 : : /*
692 : : * PageRepairFragmentation
693 : : *
694 : : * Frees fragmented space on a heap page following pruning.
695 : : *
696 : : * This routine is usable for heap pages only, but see PageIndexMultiDelete.
697 : : *
698 : : * This routine removes unused line pointers from the end of the line pointer
699 : : * array. This is possible when dead heap-only tuples get removed by pruning,
700 : : * especially when there were HOT chains with several tuples each beforehand.
701 : : *
702 : : * Caller had better have a full cleanup lock on page's buffer. As a side
703 : : * effect the page's PD_HAS_FREE_LINES hint bit will be set or unset as
704 : : * needed. Caller might also need to account for a reduction in the length of
705 : : * the line pointer array following array truncation.
706 : : */
707 : : void
708 : 88447 : PageRepairFragmentation(Page page)
709 : : {
710 : 88447 : Offset pd_lower = ((PageHeader) page)->pd_lower;
711 : 88447 : Offset pd_upper = ((PageHeader) page)->pd_upper;
712 : 88447 : Offset pd_special = ((PageHeader) page)->pd_special;
713 : : Offset last_offset;
714 : : itemIdCompactData itemidbase[MaxHeapTuplesPerPage];
715 : : itemIdCompact itemidptr;
716 : : ItemId lp;
717 : : int nline,
718 : : nstorage,
719 : : nunused;
720 : 88447 : OffsetNumber finalusedlp = InvalidOffsetNumber;
721 : : int i;
722 : : Size totallen;
723 : 88447 : bool presorted = true; /* For now */
724 : :
725 : : /*
726 : : * It's worth the trouble to be more paranoid here than in most places,
727 : : * because we are about to reshuffle data in (what is usually) a shared
728 : : * disk buffer. If we aren't careful then corrupted pointers, lengths,
729 : : * etc could cause us to clobber adjacent disk buffers, spreading the data
730 : : * loss further. So, check everything.
731 : : */
732 [ + - + - ]: 88447 : if (pd_lower < SizeOfPageHeaderData ||
733 [ + - ]: 88447 : pd_lower > pd_upper ||
734 [ + - ]: 88447 : pd_upper > pd_special ||
735 : 88447 : pd_special > BLCKSZ ||
736 [ - + ]: 88447 : pd_special != MAXALIGN(pd_special))
737 [ # # ]: 0 : ereport(ERROR,
738 : : (errcode(ERRCODE_DATA_CORRUPTED),
739 : : errmsg("corrupted page pointers: lower = %u, upper = %u, special = %u",
740 : : pd_lower, pd_upper, pd_special)));
741 : :
742 : : /*
743 : : * Run through the line pointer array and collect data about live items.
744 : : */
745 : 88447 : nline = PageGetMaxOffsetNumber(page);
746 : 88447 : itemidptr = itemidbase;
747 : 88447 : nunused = totallen = 0;
748 : 88447 : last_offset = pd_special;
749 [ + + ]: 10033661 : for (i = FirstOffsetNumber; i <= nline; i++)
750 : : {
751 : 9945214 : lp = PageGetItemId(page, i);
752 [ + + ]: 9945214 : if (ItemIdIsUsed(lp))
753 : : {
754 [ + + ]: 7664153 : if (ItemIdHasStorage(lp))
755 : : {
756 : 1975712 : itemidptr->offsetindex = i - 1;
757 : 1975712 : itemidptr->itemoff = ItemIdGetOffset(lp);
758 : :
759 [ + + ]: 1975712 : if (last_offset > itemidptr->itemoff)
760 : 1677611 : last_offset = itemidptr->itemoff;
761 : : else
762 : 298101 : presorted = false;
763 : :
764 [ + - - + : 1975712 : if (unlikely(itemidptr->itemoff < (int) pd_upper ||
- + ]
765 : : itemidptr->itemoff >= (int) pd_special))
766 [ # # ]: 0 : ereport(ERROR,
767 : : (errcode(ERRCODE_DATA_CORRUPTED),
768 : : errmsg("corrupted line pointer: %u",
769 : : itemidptr->itemoff)));
770 : 1975712 : itemidptr->alignedlen = MAXALIGN(ItemIdGetLength(lp));
771 : 1975712 : totallen += itemidptr->alignedlen;
772 : 1975712 : itemidptr++;
773 : : }
774 : :
775 : 7664153 : finalusedlp = i; /* Could be the final non-LP_UNUSED item */
776 : : }
777 : : else
778 : : {
779 : : /* Unused entries should have lp_len = 0, but make sure */
780 : : Assert(!ItemIdHasStorage(lp));
781 : 2281061 : ItemIdSetUnused(lp);
782 : 2281061 : nunused++;
783 : : }
784 : : }
785 : :
786 : 88447 : nstorage = itemidptr - itemidbase;
787 [ + + ]: 88447 : if (nstorage == 0)
788 : : {
789 : : /* Page is completely empty, so just reset it quickly */
790 : 32489 : ((PageHeader) page)->pd_upper = pd_special;
791 : : }
792 : : else
793 : : {
794 : : /* Need to compact the page the hard way */
795 [ - + ]: 55958 : if (totallen > (Size) (pd_special - pd_lower))
796 [ # # ]: 0 : ereport(ERROR,
797 : : (errcode(ERRCODE_DATA_CORRUPTED),
798 : : errmsg("corrupted item lengths: total %zu, available space %u",
799 : : totallen, pd_special - pd_lower)));
800 : :
801 : 55958 : compactify_tuples(itemidbase, nstorage, page, presorted);
802 : : }
803 : :
804 [ + + ]: 88447 : if (finalusedlp != nline)
805 : : {
806 : : /* The last line pointer is not the last used line pointer */
807 : 11249 : int nunusedend = nline - finalusedlp;
808 : :
809 : : Assert(nunused >= nunusedend && nunusedend > 0);
810 : :
811 : : /* remove trailing unused line pointers from the count */
812 : 11249 : nunused -= nunusedend;
813 : : /* truncate the line pointer array */
814 : 11249 : ((PageHeader) page)->pd_lower -= (sizeof(ItemIdData) * nunusedend);
815 : : }
816 : :
817 : : /* Set hint bit for PageAddItemExtended */
818 [ + + ]: 88447 : if (nunused > 0)
819 : 18986 : PageSetHasFreeLinePointers(page);
820 : : else
821 : 69461 : PageClearHasFreeLinePointers(page);
822 : 88447 : }
823 : :
824 : : /*
825 : : * PageTruncateLinePointerArray
826 : : *
827 : : * Removes unused line pointers at the end of the line pointer array.
828 : : *
829 : : * This routine is usable for heap pages only. It is called by VACUUM during
830 : : * its second pass over the heap. We expect at least one LP_UNUSED line
831 : : * pointer on the page (if VACUUM didn't have an LP_DEAD item on the page that
832 : : * it just set to LP_UNUSED then it should not call here).
833 : : *
834 : : * We avoid truncating the line pointer array to 0 items, if necessary by
835 : : * leaving behind a single remaining LP_UNUSED item. This is a little
836 : : * arbitrary, but it seems like a good idea to avoid leaving a PageIsEmpty()
837 : : * page behind.
838 : : *
839 : : * Caller can have either an exclusive lock or a full cleanup lock on page's
840 : : * buffer. The page's PD_HAS_FREE_LINES hint bit will be set or unset based
841 : : * on whether or not we leave behind any remaining LP_UNUSED items.
842 : : */
843 : : void
844 : 19309 : PageTruncateLinePointerArray(Page page)
845 : : {
846 : 19309 : PageHeader phdr = (PageHeader) page;
847 : 19309 : bool countdone = false,
848 : 19309 : sethint = false;
849 : 19309 : int nunusedend = 0;
850 : :
851 : : /* Scan line pointer array back-to-front */
852 [ + + ]: 1231478 : for (int i = PageGetMaxOffsetNumber(page); i >= FirstOffsetNumber; i--)
853 : : {
854 : 1230737 : ItemId lp = PageGetItemId(page, i);
855 : :
856 [ + + + + ]: 1230737 : if (!countdone && i > FirstOffsetNumber)
857 : : {
858 : : /*
859 : : * Still determining which line pointers from the end of the array
860 : : * will be truncated away. Either count another line pointer as
861 : : * safe to truncate, or notice that it's not safe to truncate
862 : : * additional line pointers (stop counting line pointers).
863 : : */
864 [ + + ]: 1106276 : if (!ItemIdIsUsed(lp))
865 : 1097215 : nunusedend++;
866 : : else
867 : 9061 : countdone = true;
868 : : }
869 : : else
870 : : {
871 : : /*
872 : : * Once we've stopped counting we still need to figure out if
873 : : * there are any remaining LP_UNUSED line pointers somewhere more
874 : : * towards the front of the array.
875 : : */
876 [ + + ]: 124461 : if (!ItemIdIsUsed(lp))
877 : : {
878 : : /*
879 : : * This is an unused line pointer that we won't be truncating
880 : : * away -- so there is at least one. Set hint on page.
881 : : */
882 : 18568 : sethint = true;
883 : 18568 : break;
884 : : }
885 : : }
886 : : }
887 : :
888 [ + + ]: 19309 : if (nunusedend > 0)
889 : : {
890 : 13483 : phdr->pd_lower -= sizeof(ItemIdData) * nunusedend;
891 : :
892 : : #ifdef CLOBBER_FREED_MEMORY
893 : : memset((char *) page + phdr->pd_lower, 0x7F,
894 : : sizeof(ItemIdData) * nunusedend);
895 : : #endif
896 : : }
897 : : else
898 : : Assert(sethint);
899 : :
900 : : /* Set hint bit for PageAddItemExtended */
901 [ + + ]: 19309 : if (sethint)
902 : 18568 : PageSetHasFreeLinePointers(page);
903 : : else
904 : 741 : PageClearHasFreeLinePointers(page);
905 : 19309 : }
906 : :
907 : : /*
908 : : * PageGetFreeSpace
909 : : * Returns the size of the free (allocatable) space on a page,
910 : : * reduced by the space needed for a new line pointer.
911 : : *
912 : : * Note: this should usually only be used on index pages. Use
913 : : * PageGetHeapFreeSpace on heap pages.
914 : : */
915 : : Size
916 : 42974924 : PageGetFreeSpace(const PageData *page)
917 : : {
918 : 42974924 : const PageHeaderData *phdr = (const PageHeaderData *) page;
919 : : int space;
920 : :
921 : : /*
922 : : * Use signed arithmetic here so that we behave sensibly if pd_lower >
923 : : * pd_upper.
924 : : */
925 : 42974924 : space = (int) phdr->pd_upper - (int) phdr->pd_lower;
926 : :
927 [ + + ]: 42974924 : if (space < (int) sizeof(ItemIdData))
928 : 10375 : return 0;
929 : 42964549 : space -= sizeof(ItemIdData);
930 : :
931 : 42964549 : return (Size) space;
932 : : }
933 : :
934 : : /*
935 : : * PageGetFreeSpaceForMultipleTuples
936 : : * Returns the size of the free (allocatable) space on a page,
937 : : * reduced by the space needed for multiple new line pointers.
938 : : *
939 : : * Note: this should usually only be used on index pages. Use
940 : : * PageGetHeapFreeSpace on heap pages.
941 : : */
942 : : Size
943 : 84559 : PageGetFreeSpaceForMultipleTuples(const PageData *page, int ntups)
944 : : {
945 : 84559 : const PageHeaderData *phdr = (const PageHeaderData *) page;
946 : : int space;
947 : :
948 : : /*
949 : : * Use signed arithmetic here so that we behave sensibly if pd_lower >
950 : : * pd_upper.
951 : : */
952 : 84559 : space = (int) phdr->pd_upper - (int) phdr->pd_lower;
953 : :
954 [ - + ]: 84559 : if (space < (int) (ntups * sizeof(ItemIdData)))
955 : 0 : return 0;
956 : 84559 : space -= ntups * sizeof(ItemIdData);
957 : :
958 : 84559 : return (Size) space;
959 : : }
960 : :
961 : : /*
962 : : * PageGetExactFreeSpace
963 : : * Returns the size of the free (allocatable) space on a page,
964 : : * without any consideration for adding/removing line pointers.
965 : : */
966 : : Size
967 : 2174878 : PageGetExactFreeSpace(const PageData *page)
968 : : {
969 : 2174878 : const PageHeaderData *phdr = (const PageHeaderData *) page;
970 : : int space;
971 : :
972 : : /*
973 : : * Use signed arithmetic here so that we behave sensibly if pd_lower >
974 : : * pd_upper.
975 : : */
976 : 2174878 : space = (int) phdr->pd_upper - (int) phdr->pd_lower;
977 : :
978 [ - + ]: 2174878 : if (space < 0)
979 : 0 : return 0;
980 : :
981 : 2174878 : return (Size) space;
982 : : }
983 : :
984 : :
985 : : /*
986 : : * PageGetHeapFreeSpace
987 : : * Returns the size of the free (allocatable) space on a page,
988 : : * reduced by the space needed for a new line pointer.
989 : : *
990 : : * The difference between this and PageGetFreeSpace is that this will return
991 : : * zero if there are already MaxHeapTuplesPerPage line pointers in the page
992 : : * and none are free. We use this to enforce that no more than
993 : : * MaxHeapTuplesPerPage line pointers are created on a heap page. (Although
994 : : * no more tuples than that could fit anyway, in the presence of redirected
995 : : * or dead line pointers it'd be possible to have too many line pointers.
996 : : * To avoid breaking code that assumes MaxHeapTuplesPerPage is a hard limit
997 : : * on the number of line pointers, we make this extra check.)
998 : : */
999 : : Size
1000 : 23252761 : PageGetHeapFreeSpace(const PageData *page)
1001 : : {
1002 : : Size space;
1003 : :
1004 : 23252761 : space = PageGetFreeSpace(page);
1005 [ + + ]: 23252761 : if (space > 0)
1006 : : {
1007 : : OffsetNumber offnum,
1008 : : nline;
1009 : :
1010 : : /*
1011 : : * Are there already MaxHeapTuplesPerPage line pointers in the page?
1012 : : */
1013 : 23224266 : nline = PageGetMaxOffsetNumber(page);
1014 [ + + ]: 23224266 : if (nline >= MaxHeapTuplesPerPage)
1015 : : {
1016 [ + + ]: 5985 : if (PageHasFreeLinePointers(page))
1017 : : {
1018 : : /*
1019 : : * Since this is just a hint, we must confirm that there is
1020 : : * indeed a free line pointer
1021 : : */
1022 [ + + ]: 568713 : for (offnum = FirstOffsetNumber; offnum <= nline; offnum = OffsetNumberNext(offnum))
1023 : : {
1024 : 568604 : ItemId lp = PageGetItemId(unconstify(PageData *, page), offnum);
1025 : :
1026 [ + + ]: 568604 : if (!ItemIdIsUsed(lp))
1027 : 3784 : break;
1028 : : }
1029 : :
1030 [ + + ]: 3893 : if (offnum > nline)
1031 : : {
1032 : : /*
1033 : : * The hint is wrong, but we can't clear it here since we
1034 : : * don't have the ability to mark the page dirty.
1035 : : */
1036 : 109 : space = 0;
1037 : : }
1038 : : }
1039 : : else
1040 : : {
1041 : : /*
1042 : : * Although the hint might be wrong, PageAddItem will believe
1043 : : * it anyway, so we must believe it too.
1044 : : */
1045 : 2092 : space = 0;
1046 : : }
1047 : : }
1048 : : }
1049 : 23252761 : return space;
1050 : : }
1051 : :
1052 : :
1053 : : /*
1054 : : * PageIndexTupleDelete
1055 : : *
1056 : : * This routine does the work of removing a tuple from an index page.
1057 : : *
1058 : : * Unlike heap pages, we compact out the line pointer for the removed tuple.
1059 : : */
1060 : : void
1061 : 628981 : PageIndexTupleDelete(Page page, OffsetNumber offnum)
1062 : : {
1063 : 628981 : PageHeader phdr = (PageHeader) page;
1064 : : char *addr;
1065 : : ItemId tup;
1066 : : Size size;
1067 : : unsigned offset;
1068 : : int nbytes;
1069 : : int offidx;
1070 : : int nline;
1071 : :
1072 : : /*
1073 : : * As with PageRepairFragmentation, paranoia seems justified.
1074 : : */
1075 [ + - ]: 628981 : if (phdr->pd_lower < SizeOfPageHeaderData ||
1076 [ + - ]: 628981 : phdr->pd_lower > phdr->pd_upper ||
1077 [ + - ]: 628981 : phdr->pd_upper > phdr->pd_special ||
1078 [ + - ]: 628981 : phdr->pd_special > BLCKSZ ||
1079 [ - + ]: 628981 : phdr->pd_special != MAXALIGN(phdr->pd_special))
1080 [ # # ]: 0 : ereport(ERROR,
1081 : : (errcode(ERRCODE_DATA_CORRUPTED),
1082 : : errmsg("corrupted page pointers: lower = %u, upper = %u, special = %u",
1083 : : phdr->pd_lower, phdr->pd_upper, phdr->pd_special)));
1084 : :
1085 : 628981 : nline = PageGetMaxOffsetNumber(page);
1086 [ + - - + ]: 628981 : if ((int) offnum <= 0 || (int) offnum > nline)
1087 [ # # ]: 0 : elog(ERROR, "invalid index offnum: %u", offnum);
1088 : :
1089 : : /* change offset number to offset index */
1090 : 628981 : offidx = offnum - 1;
1091 : :
1092 : 628981 : tup = PageGetItemId(page, offnum);
1093 : : Assert(ItemIdHasStorage(tup));
1094 : 628981 : size = ItemIdGetLength(tup);
1095 : 628981 : offset = ItemIdGetOffset(tup);
1096 : :
1097 [ + - + - ]: 628981 : if (offset < phdr->pd_upper || (offset + size) > phdr->pd_special ||
1098 [ - + ]: 628981 : offset != MAXALIGN(offset))
1099 [ # # ]: 0 : ereport(ERROR,
1100 : : (errcode(ERRCODE_DATA_CORRUPTED),
1101 : : errmsg("corrupted line pointer: offset = %u, size = %zu",
1102 : : offset, size)));
1103 : :
1104 : : /* Amount of space to actually be deleted */
1105 : 628981 : size = MAXALIGN(size);
1106 : :
1107 : : /*
1108 : : * First, we want to get rid of the pd_linp entry for the index tuple. We
1109 : : * copy all subsequent linp's back one slot in the array. We don't use
1110 : : * PageGetItemId, because we are manipulating the _array_, not individual
1111 : : * linp's.
1112 : : */
1113 : 628981 : nbytes = phdr->pd_lower -
1114 : 628981 : ((char *) &phdr->pd_linp[offidx + 1] - (char *) phdr);
1115 : :
1116 [ + + ]: 628981 : if (nbytes > 0)
1117 : 612930 : memmove(&(phdr->pd_linp[offidx]),
1118 : 612930 : &(phdr->pd_linp[offidx + 1]),
1119 : : nbytes);
1120 : :
1121 : : /*
1122 : : * Now move everything between the old upper bound (beginning of tuple
1123 : : * space) and the beginning of the deleted tuple forward, so that space in
1124 : : * the middle of the page is left free. If we've just deleted the tuple
1125 : : * at the beginning of tuple space, then there's no need to do the copy.
1126 : : */
1127 : :
1128 : : /* beginning of tuple space */
1129 : 628981 : addr = (char *) page + phdr->pd_upper;
1130 : :
1131 [ + + ]: 628981 : if (offset > phdr->pd_upper)
1132 : 613658 : memmove(addr + size, addr, offset - phdr->pd_upper);
1133 : :
1134 : : /* adjust free space boundary pointers */
1135 : 628981 : phdr->pd_upper += size;
1136 : 628981 : phdr->pd_lower -= sizeof(ItemIdData);
1137 : :
1138 : : /*
1139 : : * Finally, we need to adjust the linp entries that remain.
1140 : : *
1141 : : * Anything that used to be before the deleted tuple's data was moved
1142 : : * forward by the size of the deleted tuple.
1143 : : */
1144 [ + + ]: 628981 : if (!PageIsEmpty(page))
1145 : : {
1146 : : int i;
1147 : :
1148 : 628152 : nline--; /* there's one less than when we started */
1149 [ + + ]: 96902791 : for (i = 1; i <= nline; i++)
1150 : : {
1151 : 96274639 : ItemId ii = PageGetItemId(page, i);
1152 : :
1153 : : Assert(ItemIdHasStorage(ii));
1154 [ + + ]: 96274639 : if (ItemIdGetOffset(ii) <= offset)
1155 : 62746788 : ii->lp_off += size;
1156 : : }
1157 : : }
1158 : 628981 : }
1159 : :
1160 : :
1161 : : /*
1162 : : * PageIndexMultiDelete
1163 : : *
1164 : : * This routine handles the case of deleting multiple tuples from an
1165 : : * index page at once. It is considerably faster than a loop around
1166 : : * PageIndexTupleDelete ... however, the caller *must* supply the array
1167 : : * of item numbers to be deleted in item number order!
1168 : : */
1169 : : void
1170 : 27045 : PageIndexMultiDelete(Page page, OffsetNumber *itemnos, int nitems)
1171 : : {
1172 : 27045 : PageHeader phdr = (PageHeader) page;
1173 : 27045 : Offset pd_lower = phdr->pd_lower;
1174 : 27045 : Offset pd_upper = phdr->pd_upper;
1175 : 27045 : Offset pd_special = phdr->pd_special;
1176 : : Offset last_offset;
1177 : : itemIdCompactData itemidbase[MaxIndexTuplesPerPage];
1178 : : ItemIdData newitemids[MaxIndexTuplesPerPage];
1179 : : itemIdCompact itemidptr;
1180 : : ItemId lp;
1181 : : int nline,
1182 : : nused;
1183 : : Size totallen;
1184 : : Size size;
1185 : : unsigned offset;
1186 : : int nextitm;
1187 : : OffsetNumber offnum;
1188 : 27045 : bool presorted = true; /* For now */
1189 : :
1190 : : Assert(nitems <= MaxIndexTuplesPerPage);
1191 : :
1192 : : /*
1193 : : * If there aren't very many items to delete, then retail
1194 : : * PageIndexTupleDelete is the best way. Delete the items in reverse
1195 : : * order so we don't have to think about adjusting item numbers for
1196 : : * previous deletions.
1197 : : *
1198 : : * TODO: tune the magic number here
1199 : : */
1200 [ + + ]: 27045 : if (nitems <= 2)
1201 : : {
1202 [ + + ]: 6298 : while (--nitems >= 0)
1203 : 3601 : PageIndexTupleDelete(page, itemnos[nitems]);
1204 : 2697 : return;
1205 : : }
1206 : :
1207 : : /*
1208 : : * As with PageRepairFragmentation, paranoia seems justified.
1209 : : */
1210 [ + - + - ]: 24348 : if (pd_lower < SizeOfPageHeaderData ||
1211 [ + - ]: 24348 : pd_lower > pd_upper ||
1212 [ + - ]: 24348 : pd_upper > pd_special ||
1213 : 24348 : pd_special > BLCKSZ ||
1214 [ - + ]: 24348 : pd_special != MAXALIGN(pd_special))
1215 [ # # ]: 0 : ereport(ERROR,
1216 : : (errcode(ERRCODE_DATA_CORRUPTED),
1217 : : errmsg("corrupted page pointers: lower = %u, upper = %u, special = %u",
1218 : : pd_lower, pd_upper, pd_special)));
1219 : :
1220 : : /*
1221 : : * Scan the line pointer array and build a list of just the ones we are
1222 : : * going to keep. Notice we do not modify the page yet, since we are
1223 : : * still validity-checking.
1224 : : */
1225 : 24348 : nline = PageGetMaxOffsetNumber(page);
1226 : 24348 : itemidptr = itemidbase;
1227 : 24348 : totallen = 0;
1228 : 24348 : nused = 0;
1229 : 24348 : nextitm = 0;
1230 : 24348 : last_offset = pd_special;
1231 [ + + ]: 5490688 : for (offnum = FirstOffsetNumber; offnum <= nline; offnum = OffsetNumberNext(offnum))
1232 : : {
1233 : 5466340 : lp = PageGetItemId(page, offnum);
1234 : : Assert(ItemIdHasStorage(lp));
1235 : 5466340 : size = ItemIdGetLength(lp);
1236 : 5466340 : offset = ItemIdGetOffset(lp);
1237 [ + - ]: 5466340 : if (offset < pd_upper ||
1238 [ + - ]: 5466340 : (offset + size) > pd_special ||
1239 [ - + ]: 5466340 : offset != MAXALIGN(offset))
1240 [ # # ]: 0 : ereport(ERROR,
1241 : : (errcode(ERRCODE_DATA_CORRUPTED),
1242 : : errmsg("corrupted line pointer: offset = %u, size = %zu",
1243 : : offset, size)));
1244 : :
1245 [ + + + + ]: 5466340 : if (nextitm < nitems && offnum == itemnos[nextitm])
1246 : : {
1247 : : /* skip item to be deleted */
1248 : 2622818 : nextitm++;
1249 : : }
1250 : : else
1251 : : {
1252 : 2843522 : itemidptr->offsetindex = nused; /* where it will go */
1253 : 2843522 : itemidptr->itemoff = offset;
1254 : :
1255 [ + + ]: 2843522 : if (last_offset > itemidptr->itemoff)
1256 : 1474126 : last_offset = itemidptr->itemoff;
1257 : : else
1258 : 1369396 : presorted = false;
1259 : :
1260 : 2843522 : itemidptr->alignedlen = MAXALIGN(size);
1261 : 2843522 : totallen += itemidptr->alignedlen;
1262 : 2843522 : newitemids[nused] = *lp;
1263 : 2843522 : itemidptr++;
1264 : 2843522 : nused++;
1265 : : }
1266 : : }
1267 : :
1268 : : /* this will catch invalid or out-of-order itemnos[] */
1269 [ - + ]: 24348 : if (nextitm != nitems)
1270 [ # # ]: 0 : elog(ERROR, "incorrect index offsets supplied");
1271 : :
1272 [ - + ]: 24348 : if (totallen > (Size) (pd_special - pd_lower))
1273 [ # # ]: 0 : ereport(ERROR,
1274 : : (errcode(ERRCODE_DATA_CORRUPTED),
1275 : : errmsg("corrupted item lengths: total %zu, available space %u",
1276 : : totallen, pd_special - pd_lower)));
1277 : :
1278 : : /*
1279 : : * Looks good. Overwrite the line pointers with the copy, from which we've
1280 : : * removed all the unused items.
1281 : : */
1282 : 24348 : memcpy(phdr->pd_linp, newitemids, nused * sizeof(ItemIdData));
1283 : 24348 : phdr->pd_lower = SizeOfPageHeaderData + nused * sizeof(ItemIdData);
1284 : :
1285 : : /* and compactify the tuple data */
1286 [ + + ]: 24348 : if (nused > 0)
1287 : 23954 : compactify_tuples(itemidbase, nused, page, presorted);
1288 : : else
1289 : 394 : phdr->pd_upper = pd_special;
1290 : : }
1291 : :
1292 : :
1293 : : /*
1294 : : * PageIndexTupleDeleteNoCompact
1295 : : *
1296 : : * Remove the specified tuple from an index page, but set its line pointer
1297 : : * to "unused" instead of compacting it out, except that it can be removed
1298 : : * if it's the last line pointer on the page.
1299 : : *
1300 : : * This is used for index AMs that require that existing TIDs of live tuples
1301 : : * remain unchanged, and are willing to allow unused line pointers instead.
1302 : : */
1303 : : void
1304 : 348 : PageIndexTupleDeleteNoCompact(Page page, OffsetNumber offnum)
1305 : : {
1306 : 348 : PageHeader phdr = (PageHeader) page;
1307 : : char *addr;
1308 : : ItemId tup;
1309 : : Size size;
1310 : : unsigned offset;
1311 : : int nline;
1312 : :
1313 : : /*
1314 : : * As with PageRepairFragmentation, paranoia seems justified.
1315 : : */
1316 [ + - ]: 348 : if (phdr->pd_lower < SizeOfPageHeaderData ||
1317 [ + - ]: 348 : phdr->pd_lower > phdr->pd_upper ||
1318 [ + - ]: 348 : phdr->pd_upper > phdr->pd_special ||
1319 [ + - ]: 348 : phdr->pd_special > BLCKSZ ||
1320 [ - + ]: 348 : phdr->pd_special != MAXALIGN(phdr->pd_special))
1321 [ # # ]: 0 : ereport(ERROR,
1322 : : (errcode(ERRCODE_DATA_CORRUPTED),
1323 : : errmsg("corrupted page pointers: lower = %u, upper = %u, special = %u",
1324 : : phdr->pd_lower, phdr->pd_upper, phdr->pd_special)));
1325 : :
1326 : 348 : nline = PageGetMaxOffsetNumber(page);
1327 [ + - - + ]: 348 : if ((int) offnum <= 0 || (int) offnum > nline)
1328 [ # # ]: 0 : elog(ERROR, "invalid index offnum: %u", offnum);
1329 : :
1330 : 348 : tup = PageGetItemId(page, offnum);
1331 : : Assert(ItemIdHasStorage(tup));
1332 : 348 : size = ItemIdGetLength(tup);
1333 : 348 : offset = ItemIdGetOffset(tup);
1334 : :
1335 [ + - + - ]: 348 : if (offset < phdr->pd_upper || (offset + size) > phdr->pd_special ||
1336 [ - + ]: 348 : offset != MAXALIGN(offset))
1337 [ # # ]: 0 : ereport(ERROR,
1338 : : (errcode(ERRCODE_DATA_CORRUPTED),
1339 : : errmsg("corrupted line pointer: offset = %u, size = %zu",
1340 : : offset, size)));
1341 : :
1342 : : /* Amount of space to actually be deleted */
1343 : 348 : size = MAXALIGN(size);
1344 : :
1345 : : /*
1346 : : * Either set the line pointer to "unused", or zap it if it's the last
1347 : : * one. (Note: it's possible that the next-to-last one(s) are already
1348 : : * unused, but we do not trouble to try to compact them out if so.)
1349 : : */
1350 [ + + ]: 348 : if ((int) offnum < nline)
1351 : 308 : ItemIdSetUnused(tup);
1352 : : else
1353 : : {
1354 : 40 : phdr->pd_lower -= sizeof(ItemIdData);
1355 : 40 : nline--; /* there's one less than when we started */
1356 : : }
1357 : :
1358 : : /*
1359 : : * Now move everything between the old upper bound (beginning of tuple
1360 : : * space) and the beginning of the deleted tuple forward, so that space in
1361 : : * the middle of the page is left free. If we've just deleted the tuple
1362 : : * at the beginning of tuple space, then there's no need to do the copy.
1363 : : */
1364 : :
1365 : : /* beginning of tuple space */
1366 : 348 : addr = (char *) page + phdr->pd_upper;
1367 : :
1368 [ + + ]: 348 : if (offset > phdr->pd_upper)
1369 : 308 : memmove(addr + size, addr, offset - phdr->pd_upper);
1370 : :
1371 : : /* adjust free space boundary pointer */
1372 : 348 : phdr->pd_upper += size;
1373 : :
1374 : : /*
1375 : : * Finally, we need to adjust the linp entries that remain.
1376 : : *
1377 : : * Anything that used to be before the deleted tuple's data was moved
1378 : : * forward by the size of the deleted tuple.
1379 : : */
1380 [ + + ]: 348 : if (!PageIsEmpty(page))
1381 : : {
1382 : : int i;
1383 : :
1384 [ + + ]: 86593 : for (i = 1; i <= nline; i++)
1385 : : {
1386 : 86251 : ItemId ii = PageGetItemId(page, i);
1387 : :
1388 [ + + + + ]: 86251 : if (ItemIdHasStorage(ii) && ItemIdGetOffset(ii) <= offset)
1389 : 42304 : ii->lp_off += size;
1390 : : }
1391 : : }
1392 : 348 : }
1393 : :
1394 : :
1395 : : /*
1396 : : * PageIndexTupleOverwrite
1397 : : *
1398 : : * Replace a specified tuple on an index page.
1399 : : *
1400 : : * The new tuple is placed exactly where the old one had been, shifting
1401 : : * other tuples' data up or down as needed to keep the page compacted.
1402 : : * This is better than deleting and reinserting the tuple, because it
1403 : : * avoids any data shifting when the tuple size doesn't change; and
1404 : : * even when it does, we avoid moving the line pointers around.
1405 : : * This could be used by an index AM that doesn't want to unset the
1406 : : * LP_DEAD bit when it happens to be set. It could conceivably also be
1407 : : * used by an index AM that cares about the physical order of tuples as
1408 : : * well as their logical/ItemId order.
1409 : : *
1410 : : * If there's insufficient space for the new tuple, return false. Other
1411 : : * errors represent data-corruption problems, so we just elog.
1412 : : */
1413 : : bool
1414 : 583799 : PageIndexTupleOverwrite(Page page, OffsetNumber offnum,
1415 : : const void *newtup, Size newsize)
1416 : : {
1417 : 583799 : PageHeader phdr = (PageHeader) page;
1418 : : ItemId tupid;
1419 : : int oldsize;
1420 : : unsigned offset;
1421 : : Size alignednewsize;
1422 : : int size_diff;
1423 : : int itemcount;
1424 : :
1425 : : /*
1426 : : * As with PageRepairFragmentation, paranoia seems justified.
1427 : : */
1428 [ + - ]: 583799 : if (phdr->pd_lower < SizeOfPageHeaderData ||
1429 [ + - ]: 583799 : phdr->pd_lower > phdr->pd_upper ||
1430 [ + - ]: 583799 : phdr->pd_upper > phdr->pd_special ||
1431 [ + - ]: 583799 : phdr->pd_special > BLCKSZ ||
1432 [ - + ]: 583799 : phdr->pd_special != MAXALIGN(phdr->pd_special))
1433 [ # # ]: 0 : ereport(ERROR,
1434 : : (errcode(ERRCODE_DATA_CORRUPTED),
1435 : : errmsg("corrupted page pointers: lower = %u, upper = %u, special = %u",
1436 : : phdr->pd_lower, phdr->pd_upper, phdr->pd_special)));
1437 : :
1438 : 583799 : itemcount = PageGetMaxOffsetNumber(page);
1439 [ + - - + ]: 583799 : if ((int) offnum <= 0 || (int) offnum > itemcount)
1440 [ # # ]: 0 : elog(ERROR, "invalid index offnum: %u", offnum);
1441 : :
1442 : 583799 : tupid = PageGetItemId(page, offnum);
1443 : : Assert(ItemIdHasStorage(tupid));
1444 : 583799 : oldsize = ItemIdGetLength(tupid);
1445 : 583799 : offset = ItemIdGetOffset(tupid);
1446 : :
1447 [ + - + - ]: 583799 : if (offset < phdr->pd_upper || (offset + oldsize) > phdr->pd_special ||
1448 [ - + ]: 583799 : offset != MAXALIGN(offset))
1449 [ # # ]: 0 : ereport(ERROR,
1450 : : (errcode(ERRCODE_DATA_CORRUPTED),
1451 : : errmsg("corrupted line pointer: offset = %u, size = %d",
1452 : : offset, oldsize)));
1453 : :
1454 : : /*
1455 : : * Determine actual change in space requirement, check for page overflow.
1456 : : */
1457 : 583799 : oldsize = MAXALIGN(oldsize);
1458 : 583799 : alignednewsize = MAXALIGN(newsize);
1459 [ - + ]: 583799 : if (alignednewsize > oldsize + (phdr->pd_upper - phdr->pd_lower))
1460 : 0 : return false;
1461 : :
1462 : : /*
1463 : : * Relocate existing data and update line pointers, unless the new tuple
1464 : : * is the same size as the old (after alignment), in which case there's
1465 : : * nothing to do. Notice that what we have to relocate is data before the
1466 : : * target tuple, not data after, so it's convenient to express size_diff
1467 : : * as the amount by which the tuple's size is decreasing, making it the
1468 : : * delta to add to pd_upper and affected line pointers.
1469 : : */
1470 : 583799 : size_diff = oldsize - (int) alignednewsize;
1471 [ + + ]: 583799 : if (size_diff != 0)
1472 : : {
1473 : 91433 : char *addr = (char *) page + phdr->pd_upper;
1474 : : int i;
1475 : :
1476 : : /* relocate all tuple data before the target tuple */
1477 : 91433 : memmove(addr + size_diff, addr, offset - phdr->pd_upper);
1478 : :
1479 : : /* adjust free space boundary pointer */
1480 : 91433 : phdr->pd_upper += size_diff;
1481 : :
1482 : : /* adjust affected line pointers too */
1483 [ + + ]: 17090912 : for (i = FirstOffsetNumber; i <= itemcount; i++)
1484 : : {
1485 : 16999479 : ItemId ii = PageGetItemId(page, i);
1486 : :
1487 : : /* Allow items without storage; currently only BRIN needs that */
1488 [ + + + + ]: 16999479 : if (ItemIdHasStorage(ii) && ItemIdGetOffset(ii) <= offset)
1489 : 8686592 : ii->lp_off += size_diff;
1490 : : }
1491 : : }
1492 : :
1493 : : /* Update the item's tuple length without changing its lp_flags field */
1494 : 583799 : tupid->lp_off = offset + size_diff;
1495 : 583799 : tupid->lp_len = newsize;
1496 : :
1497 : : /* Copy new tuple data onto page */
1498 : 583799 : memcpy(PageGetItem(page, tupid), newtup, newsize);
1499 : :
1500 : 583799 : return true;
1501 : : }
1502 : :
1503 : :
1504 : : /*
1505 : : * Set checksum on a page.
1506 : : *
1507 : : * If the page is in shared buffers, it needs to be locked in at least
1508 : : * share-exclusive mode.
1509 : : *
1510 : : * If checksums are disabled, or if the page is not initialized, just
1511 : : * return. Otherwise compute and set the checksum.
1512 : : *
1513 : : * In the past this needed to be done on a copy of the page, due to the
1514 : : * possibility of e.g., hint bits being set concurrently. However, this is not
1515 : : * necessary anymore as hint bits won't be set while IO is going on.
1516 : : */
1517 : : void
1518 : 801551 : PageSetChecksum(Page page, BlockNumber blkno)
1519 : : {
1520 : 801551 : HOLD_INTERRUPTS();
1521 : : /* If we don't need a checksum, just return */
1522 [ + + + + ]: 801551 : if (PageIsNew(page) || !DataChecksumsNeedWrite())
1523 : : {
1524 : 58579 : RESUME_INTERRUPTS();
1525 : 58579 : return;
1526 : : }
1527 : :
1528 : 742972 : ((PageHeader) page)->pd_checksum = pg_checksum_page(page, blkno);
1529 : 742972 : RESUME_INTERRUPTS();
1530 : : }
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