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gistutil.c
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1 /*-------------------------------------------------------------------------
2  *
3  * gistutil.c
4  * utilities routines for the postgres GiST index access method.
5  *
6  *
7  * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
8  * Portions Copyright (c) 1994, Regents of the University of California
9  *
10  * IDENTIFICATION
11  * src/backend/access/gist/gistutil.c
12  *-------------------------------------------------------------------------
13  */
14 #include "postgres.h"
15 
16 #include <math.h>
17 
18 #include "access/gist_private.h"
19 #include "access/htup_details.h"
20 #include "access/reloptions.h"
21 #include "catalog/pg_opclass.h"
22 #include "storage/indexfsm.h"
23 #include "storage/lmgr.h"
24 #include "utils/float.h"
25 #include "utils/syscache.h"
26 #include "utils/snapmgr.h"
27 #include "utils/lsyscache.h"
28 
29 
30 /*
31  * Write itup vector to page, has no control of free space.
32  */
33 void
34 gistfillbuffer(Page page, IndexTuple *itup, int len, OffsetNumber off)
35 {
37  int i;
38 
39  if (off == InvalidOffsetNumber)
40  off = (PageIsEmpty(page)) ? FirstOffsetNumber :
42 
43  for (i = 0; i < len; i++)
44  {
45  Size sz = IndexTupleSize(itup[i]);
46 
47  l = PageAddItem(page, (Item) itup[i], sz, off, false, false);
48  if (l == InvalidOffsetNumber)
49  elog(ERROR, "failed to add item to GiST index page, item %d out of %d, size %d bytes",
50  i, len, (int) sz);
51  off++;
52  }
53 }
54 
55 /*
56  * Check space for itup vector on page
57  */
58 bool
59 gistnospace(Page page, IndexTuple *itvec, int len, OffsetNumber todelete, Size freespace)
60 {
61  unsigned int size = freespace,
62  deleted = 0;
63  int i;
64 
65  for (i = 0; i < len; i++)
66  size += IndexTupleSize(itvec[i]) + sizeof(ItemIdData);
67 
68  if (todelete != InvalidOffsetNumber)
69  {
70  IndexTuple itup = (IndexTuple) PageGetItem(page, PageGetItemId(page, todelete));
71 
72  deleted = IndexTupleSize(itup) + sizeof(ItemIdData);
73  }
74 
75  return (PageGetFreeSpace(page) + deleted < size);
76 }
77 
78 bool
79 gistfitpage(IndexTuple *itvec, int len)
80 {
81  int i;
82  Size size = 0;
83 
84  for (i = 0; i < len; i++)
85  size += IndexTupleSize(itvec[i]) + sizeof(ItemIdData);
86 
87  /* TODO: Consider fillfactor */
88  return (size <= GiSTPageSize);
89 }
90 
91 /*
92  * Read buffer into itup vector
93  */
94 IndexTuple *
95 gistextractpage(Page page, int *len /* out */ )
96 {
98  maxoff;
99  IndexTuple *itvec;
100 
101  maxoff = PageGetMaxOffsetNumber(page);
102  *len = maxoff;
103  itvec = palloc(sizeof(IndexTuple) * maxoff);
104  for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
105  itvec[i - FirstOffsetNumber] = (IndexTuple) PageGetItem(page, PageGetItemId(page, i));
106 
107  return itvec;
108 }
109 
110 /*
111  * join two vectors into one
112  */
113 IndexTuple *
114 gistjoinvector(IndexTuple *itvec, int *len, IndexTuple *additvec, int addlen)
115 {
116  itvec = (IndexTuple *) repalloc((void *) itvec, sizeof(IndexTuple) * ((*len) + addlen));
117  memmove(&itvec[*len], additvec, sizeof(IndexTuple) * addlen);
118  *len += addlen;
119  return itvec;
120 }
121 
122 /*
123  * make plain IndexTuple vector
124  */
125 
127 gistfillitupvec(IndexTuple *vec, int veclen, int *memlen)
128 {
129  char *ptr,
130  *ret;
131  int i;
132 
133  *memlen = 0;
134 
135  for (i = 0; i < veclen; i++)
136  *memlen += IndexTupleSize(vec[i]);
137 
138  ptr = ret = palloc(*memlen);
139 
140  for (i = 0; i < veclen; i++)
141  {
142  memcpy(ptr, vec[i], IndexTupleSize(vec[i]));
143  ptr += IndexTupleSize(vec[i]);
144  }
145 
146  return (IndexTupleData *) ret;
147 }
148 
149 /*
150  * Make unions of keys in IndexTuple vector (one union datum per index column).
151  * Union Datums are returned into the attr/isnull arrays.
152  * Resulting Datums aren't compressed.
153  */
154 void
155 gistMakeUnionItVec(GISTSTATE *giststate, IndexTuple *itvec, int len,
156  Datum *attr, bool *isnull)
157 {
158  int i;
159  GistEntryVector *evec;
160  int attrsize;
161 
162  evec = (GistEntryVector *) palloc((len + 2) * sizeof(GISTENTRY) + GEVHDRSZ);
163 
164  for (i = 0; i < giststate->nonLeafTupdesc->natts; i++)
165  {
166  int j;
167 
168  /* Collect non-null datums for this column */
169  evec->n = 0;
170  for (j = 0; j < len; j++)
171  {
172  Datum datum;
173  bool IsNull;
174 
175  datum = index_getattr(itvec[j], i + 1, giststate->leafTupdesc,
176  &IsNull);
177  if (IsNull)
178  continue;
179 
180  gistdentryinit(giststate, i,
181  evec->vector + evec->n,
182  datum,
183  NULL, NULL, (OffsetNumber) 0,
184  false, IsNull);
185  evec->n++;
186  }
187 
188  /* If this column was all NULLs, the union is NULL */
189  if (evec->n == 0)
190  {
191  attr[i] = (Datum) 0;
192  isnull[i] = true;
193  }
194  else
195  {
196  if (evec->n == 1)
197  {
198  /* unionFn may expect at least two inputs */
199  evec->n = 2;
200  evec->vector[1] = evec->vector[0];
201  }
202 
203  /* Make union and store in attr array */
204  attr[i] = FunctionCall2Coll(&giststate->unionFn[i],
205  giststate->supportCollation[i],
206  PointerGetDatum(evec),
207  PointerGetDatum(&attrsize));
208 
209  isnull[i] = false;
210  }
211  }
212 }
213 
214 /*
215  * Return an IndexTuple containing the result of applying the "union"
216  * method to the specified IndexTuple vector.
217  */
219 gistunion(Relation r, IndexTuple *itvec, int len, GISTSTATE *giststate)
220 {
221  Datum attr[INDEX_MAX_KEYS];
222  bool isnull[INDEX_MAX_KEYS];
223 
224  gistMakeUnionItVec(giststate, itvec, len, attr, isnull);
225 
226  return gistFormTuple(giststate, r, attr, isnull, false);
227 }
228 
229 /*
230  * makes union of two key
231  */
232 void
233 gistMakeUnionKey(GISTSTATE *giststate, int attno,
234  GISTENTRY *entry1, bool isnull1,
235  GISTENTRY *entry2, bool isnull2,
236  Datum *dst, bool *dstisnull)
237 {
238  /* we need a GistEntryVector with room for exactly 2 elements */
239  union
240  {
241  GistEntryVector gev;
242  char padding[2 * sizeof(GISTENTRY) + GEVHDRSZ];
243  } storage;
244  GistEntryVector *evec = &storage.gev;
245  int dstsize;
246 
247  evec->n = 2;
248 
249  if (isnull1 && isnull2)
250  {
251  *dstisnull = true;
252  *dst = (Datum) 0;
253  }
254  else
255  {
256  if (isnull1 == false && isnull2 == false)
257  {
258  evec->vector[0] = *entry1;
259  evec->vector[1] = *entry2;
260  }
261  else if (isnull1 == false)
262  {
263  evec->vector[0] = *entry1;
264  evec->vector[1] = *entry1;
265  }
266  else
267  {
268  evec->vector[0] = *entry2;
269  evec->vector[1] = *entry2;
270  }
271 
272  *dstisnull = false;
273  *dst = FunctionCall2Coll(&giststate->unionFn[attno],
274  giststate->supportCollation[attno],
275  PointerGetDatum(evec),
276  PointerGetDatum(&dstsize));
277  }
278 }
279 
280 bool
281 gistKeyIsEQ(GISTSTATE *giststate, int attno, Datum a, Datum b)
282 {
283  bool result;
284 
285  FunctionCall3Coll(&giststate->equalFn[attno],
286  giststate->supportCollation[attno],
287  a, b,
288  PointerGetDatum(&result));
289  return result;
290 }
291 
292 /*
293  * Decompress all keys in tuple
294  */
295 void
297  OffsetNumber o, GISTENTRY *attdata, bool *isnull)
298 {
299  int i;
300 
301  for (i = 0; i < IndexRelationGetNumberOfKeyAttributes(r); i++)
302  {
303  Datum datum;
304 
305  datum = index_getattr(tuple, i + 1, giststate->leafTupdesc, &isnull[i]);
306  gistdentryinit(giststate, i, &attdata[i],
307  datum, r, p, o,
308  false, isnull[i]);
309  }
310 }
311 
312 /*
313  * Forms union of oldtup and addtup, if union == oldtup then return NULL
314  */
317 {
318  bool neednew = false;
319  GISTENTRY oldentries[INDEX_MAX_KEYS],
320  addentries[INDEX_MAX_KEYS];
321  bool oldisnull[INDEX_MAX_KEYS],
322  addisnull[INDEX_MAX_KEYS];
323  Datum attr[INDEX_MAX_KEYS];
324  bool isnull[INDEX_MAX_KEYS];
325  IndexTuple newtup = NULL;
326  int i;
327 
328  gistDeCompressAtt(giststate, r, oldtup, NULL,
329  (OffsetNumber) 0, oldentries, oldisnull);
330 
331  gistDeCompressAtt(giststate, r, addtup, NULL,
332  (OffsetNumber) 0, addentries, addisnull);
333 
334  for (i = 0; i < IndexRelationGetNumberOfKeyAttributes(r); i++)
335  {
336  gistMakeUnionKey(giststate, i,
337  oldentries + i, oldisnull[i],
338  addentries + i, addisnull[i],
339  attr + i, isnull + i);
340 
341  if (neednew)
342  /* we already need new key, so we can skip check */
343  continue;
344 
345  if (isnull[i])
346  /* union of key may be NULL if and only if both keys are NULL */
347  continue;
348 
349  if (!addisnull[i])
350  {
351  if (oldisnull[i] ||
352  !gistKeyIsEQ(giststate, i, oldentries[i].key, attr[i]))
353  neednew = true;
354  }
355  }
356 
357  if (neednew)
358  {
359  /* need to update key */
360  newtup = gistFormTuple(giststate, r, attr, isnull, false);
361  newtup->t_tid = oldtup->t_tid;
362  }
363 
364  return newtup;
365 }
366 
367 /*
368  * Search an upper index page for the entry with lowest penalty for insertion
369  * of the new index key contained in "it".
370  *
371  * Returns the index of the page entry to insert into.
372  */
374 gistchoose(Relation r, Page p, IndexTuple it, /* it has compressed entry */
375  GISTSTATE *giststate)
376 {
377  OffsetNumber result;
378  OffsetNumber maxoff;
379  OffsetNumber i;
380  float best_penalty[INDEX_MAX_KEYS];
381  GISTENTRY entry,
382  identry[INDEX_MAX_KEYS];
383  bool isnull[INDEX_MAX_KEYS];
384  int keep_current_best;
385 
386  Assert(!GistPageIsLeaf(p));
387 
388  gistDeCompressAtt(giststate, r,
389  it, NULL, (OffsetNumber) 0,
390  identry, isnull);
391 
392  /* we'll return FirstOffsetNumber if page is empty (shouldn't happen) */
393  result = FirstOffsetNumber;
394 
395  /*
396  * The index may have multiple columns, and there's a penalty value for
397  * each column. The penalty associated with a column that appears earlier
398  * in the index definition is strictly more important than the penalty of
399  * a column that appears later in the index definition.
400  *
401  * best_penalty[j] is the best penalty we have seen so far for column j,
402  * or -1 when we haven't yet examined column j. Array entries to the
403  * right of the first -1 are undefined.
404  */
405  best_penalty[0] = -1;
406 
407  /*
408  * If we find a tuple that's exactly as good as the currently best one, we
409  * could use either one. When inserting a lot of tuples with the same or
410  * similar keys, it's preferable to descend down the same path when
411  * possible, as that's more cache-friendly. On the other hand, if all
412  * inserts land on the same leaf page after a split, we're never going to
413  * insert anything to the other half of the split, and will end up using
414  * only 50% of the available space. Distributing the inserts evenly would
415  * lead to better space usage, but that hurts cache-locality during
416  * insertion. To get the best of both worlds, when we find a tuple that's
417  * exactly as good as the previous best, choose randomly whether to stick
418  * to the old best, or use the new one. Once we decide to stick to the
419  * old best, we keep sticking to it for any subsequent equally good tuples
420  * we might find. This favors tuples with low offsets, but still allows
421  * some inserts to go to other equally-good subtrees.
422  *
423  * keep_current_best is -1 if we haven't yet had to make a random choice
424  * whether to keep the current best tuple. If we have done so, and
425  * decided to keep it, keep_current_best is 1; if we've decided to
426  * replace, keep_current_best is 0. (This state will be reset to -1 as
427  * soon as we've made the replacement, but sometimes we make the choice in
428  * advance of actually finding a replacement best tuple.)
429  */
430  keep_current_best = -1;
431 
432  /*
433  * Loop over tuples on page.
434  */
435  maxoff = PageGetMaxOffsetNumber(p);
436  Assert(maxoff >= FirstOffsetNumber);
437 
438  for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
439  {
440  IndexTuple itup = (IndexTuple) PageGetItem(p, PageGetItemId(p, i));
441  bool zero_penalty;
442  int j;
443 
444  zero_penalty = true;
445 
446  /* Loop over index attributes. */
447  for (j = 0; j < IndexRelationGetNumberOfKeyAttributes(r); j++)
448  {
449  Datum datum;
450  float usize;
451  bool IsNull;
452 
453  /* Compute penalty for this column. */
454  datum = index_getattr(itup, j + 1, giststate->leafTupdesc,
455  &IsNull);
456  gistdentryinit(giststate, j, &entry, datum, r, p, i,
457  false, IsNull);
458  usize = gistpenalty(giststate, j, &entry, IsNull,
459  &identry[j], isnull[j]);
460  if (usize > 0)
461  zero_penalty = false;
462 
463  if (best_penalty[j] < 0 || usize < best_penalty[j])
464  {
465  /*
466  * New best penalty for column. Tentatively select this tuple
467  * as the target, and record the best penalty. Then reset the
468  * next column's penalty to "unknown" (and indirectly, the
469  * same for all the ones to its right). This will force us to
470  * adopt this tuple's penalty values as the best for all the
471  * remaining columns during subsequent loop iterations.
472  */
473  result = i;
474  best_penalty[j] = usize;
475 
477  best_penalty[j + 1] = -1;
478 
479  /* we have new best, so reset keep-it decision */
480  keep_current_best = -1;
481  }
482  else if (best_penalty[j] == usize)
483  {
484  /*
485  * The current tuple is exactly as good for this column as the
486  * best tuple seen so far. The next iteration of this loop
487  * will compare the next column.
488  */
489  }
490  else
491  {
492  /*
493  * The current tuple is worse for this column than the best
494  * tuple seen so far. Skip the remaining columns and move on
495  * to the next tuple, if any.
496  */
497  zero_penalty = false; /* so outer loop won't exit */
498  break;
499  }
500  }
501 
502  /*
503  * If we looped past the last column, and did not update "result",
504  * then this tuple is exactly as good as the prior best tuple.
505  */
506  if (j == IndexRelationGetNumberOfKeyAttributes(r) && result != i)
507  {
508  if (keep_current_best == -1)
509  {
510  /* we didn't make the random choice yet for this old best */
511  keep_current_best = (random() <= (MAX_RANDOM_VALUE / 2)) ? 1 : 0;
512  }
513  if (keep_current_best == 0)
514  {
515  /* we choose to use the new tuple */
516  result = i;
517  /* choose again if there are even more exactly-as-good ones */
518  keep_current_best = -1;
519  }
520  }
521 
522  /*
523  * If we find a tuple with zero penalty for all columns, and we've
524  * decided we don't want to search for another tuple with equal
525  * penalty, there's no need to examine remaining tuples; just break
526  * out of the loop and return it.
527  */
528  if (zero_penalty)
529  {
530  if (keep_current_best == -1)
531  {
532  /* we didn't make the random choice yet for this old best */
533  keep_current_best = (random() <= (MAX_RANDOM_VALUE / 2)) ? 1 : 0;
534  }
535  if (keep_current_best == 1)
536  break;
537  }
538  }
539 
540  return result;
541 }
542 
543 /*
544  * initialize a GiST entry with a decompressed version of key
545  */
546 void
547 gistdentryinit(GISTSTATE *giststate, int nkey, GISTENTRY *e,
548  Datum k, Relation r, Page pg, OffsetNumber o,
549  bool l, bool isNull)
550 {
551  if (!isNull)
552  {
553  GISTENTRY *dep;
554 
555  gistentryinit(*e, k, r, pg, o, l);
556 
557  /* there may not be a decompress function in opclass */
558  if (!OidIsValid(giststate->decompressFn[nkey].fn_oid))
559  return;
560 
561  dep = (GISTENTRY *)
563  giststate->supportCollation[nkey],
564  PointerGetDatum(e)));
565  /* decompressFn may just return the given pointer */
566  if (dep != e)
567  gistentryinit(*e, dep->key, dep->rel, dep->page, dep->offset,
568  dep->leafkey);
569  }
570  else
571  gistentryinit(*e, (Datum) 0, r, pg, o, l);
572 }
573 
576  Datum attdata[], bool isnull[], bool isleaf)
577 {
578  Datum compatt[INDEX_MAX_KEYS];
579  int i;
580  IndexTuple res;
581 
582  /*
583  * Call the compress method on each attribute.
584  */
585  for (i = 0; i < IndexRelationGetNumberOfKeyAttributes(r); i++)
586  {
587  if (isnull[i])
588  compatt[i] = (Datum) 0;
589  else
590  {
591  GISTENTRY centry;
592  GISTENTRY *cep;
593 
594  gistentryinit(centry, attdata[i], r, NULL, (OffsetNumber) 0,
595  isleaf);
596  /* there may not be a compress function in opclass */
597  if (OidIsValid(giststate->compressFn[i].fn_oid))
598  cep = (GISTENTRY *)
600  giststate->supportCollation[i],
601  PointerGetDatum(&centry)));
602  else
603  cep = &centry;
604  compatt[i] = cep->key;
605  }
606  }
607 
608  if (isleaf)
609  {
610  /*
611  * Emplace each included attribute if any.
612  */
613  for (; i < r->rd_att->natts; i++)
614  {
615  if (isnull[i])
616  compatt[i] = (Datum) 0;
617  else
618  compatt[i] = attdata[i];
619  }
620  }
621 
622  res = index_form_tuple(isleaf ? giststate->leafTupdesc :
623  giststate->nonLeafTupdesc,
624  compatt, isnull);
625 
626  /*
627  * The offset number on tuples on internal pages is unused. For historical
628  * reasons, it is set to 0xffff.
629  */
630  ItemPointerSetOffsetNumber(&(res->t_tid), 0xffff);
631  return res;
632 }
633 
634 /*
635  * initialize a GiST entry with fetched value in key field
636  */
637 static Datum
638 gistFetchAtt(GISTSTATE *giststate, int nkey, Datum k, Relation r)
639 {
640  GISTENTRY fentry;
641  GISTENTRY *fep;
642 
643  gistentryinit(fentry, k, r, NULL, (OffsetNumber) 0, false);
644 
645  fep = (GISTENTRY *)
646  DatumGetPointer(FunctionCall1Coll(&giststate->fetchFn[nkey],
647  giststate->supportCollation[nkey],
648  PointerGetDatum(&fentry)));
649 
650  /* fetchFn set 'key', return it to the caller */
651  return fep->key;
652 }
653 
654 /*
655  * Fetch all keys in tuple.
656  * Returns a new HeapTuple containing the originally-indexed data.
657  */
658 HeapTuple
660 {
661  MemoryContext oldcxt = MemoryContextSwitchTo(giststate->tempCxt);
663  bool isnull[INDEX_MAX_KEYS];
664  int i;
665 
666  for (i = 0; i < IndexRelationGetNumberOfKeyAttributes(r); i++)
667  {
668  Datum datum;
669 
670  datum = index_getattr(tuple, i + 1, giststate->leafTupdesc, &isnull[i]);
671 
672  if (giststate->fetchFn[i].fn_oid != InvalidOid)
673  {
674  if (!isnull[i])
675  fetchatt[i] = gistFetchAtt(giststate, i, datum, r);
676  else
677  fetchatt[i] = (Datum) 0;
678  }
679  else if (giststate->compressFn[i].fn_oid == InvalidOid)
680  {
681  /*
682  * If opclass does not provide compress method that could change
683  * original value, att is necessarily stored in original form.
684  */
685  if (!isnull[i])
686  fetchatt[i] = datum;
687  else
688  fetchatt[i] = (Datum) 0;
689  }
690  else
691  {
692  /*
693  * Index-only scans not supported for this column. Since the
694  * planner chose an index-only scan anyway, it is not interested
695  * in this column, and we can replace it with a NULL.
696  */
697  isnull[i] = true;
698  fetchatt[i] = (Datum) 0;
699  }
700  }
701 
702  /*
703  * Get each included attribute.
704  */
705  for (; i < r->rd_att->natts; i++)
706  {
707  fetchatt[i] = index_getattr(tuple, i + 1, giststate->leafTupdesc,
708  &isnull[i]);
709  }
710  MemoryContextSwitchTo(oldcxt);
711 
712  return heap_form_tuple(giststate->fetchTupdesc, fetchatt, isnull);
713 }
714 
715 float
716 gistpenalty(GISTSTATE *giststate, int attno,
717  GISTENTRY *orig, bool isNullOrig,
718  GISTENTRY *add, bool isNullAdd)
719 {
720  float penalty = 0.0;
721 
722  if (giststate->penaltyFn[attno].fn_strict == false ||
723  (isNullOrig == false && isNullAdd == false))
724  {
725  FunctionCall3Coll(&giststate->penaltyFn[attno],
726  giststate->supportCollation[attno],
727  PointerGetDatum(orig),
728  PointerGetDatum(add),
729  PointerGetDatum(&penalty));
730  /* disallow negative or NaN penalty */
731  if (isnan(penalty) || penalty < 0.0)
732  penalty = 0.0;
733  }
734  else if (isNullOrig && isNullAdd)
735  penalty = 0.0;
736  else
737  {
738  /* try to prevent mixing null and non-null values */
739  penalty = get_float4_infinity();
740  }
741 
742  return penalty;
743 }
744 
745 /*
746  * Initialize a new index page
747  */
748 void
750 {
751  GISTPageOpaque opaque;
752  Page page;
753  Size pageSize;
754 
755  pageSize = BufferGetPageSize(b);
756  page = BufferGetPage(b);
757  PageInit(page, pageSize, sizeof(GISTPageOpaqueData));
758 
759  opaque = GistPageGetOpaque(page);
760  /* page was already zeroed by PageInit, so this is not needed: */
761  /* memset(&(opaque->nsn), 0, sizeof(GistNSN)); */
762  opaque->rightlink = InvalidBlockNumber;
763  opaque->flags = f;
764  opaque->gist_page_id = GIST_PAGE_ID;
765 }
766 
767 /*
768  * Verify that a freshly-read page looks sane.
769  */
770 void
772 {
773  Page page = BufferGetPage(buf);
774 
775  /*
776  * ReadBuffer verifies that every newly-read page passes
777  * PageHeaderIsValid, which means it either contains a reasonably sane
778  * page header or is all-zero. We have to defend against the all-zero
779  * case, however.
780  */
781  if (PageIsNew(page))
782  ereport(ERROR,
783  (errcode(ERRCODE_INDEX_CORRUPTED),
784  errmsg("index \"%s\" contains unexpected zero page at block %u",
786  BufferGetBlockNumber(buf)),
787  errhint("Please REINDEX it.")));
788 
789  /*
790  * Additionally check that the special area looks sane.
791  */
792  if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GISTPageOpaqueData)))
793  ereport(ERROR,
794  (errcode(ERRCODE_INDEX_CORRUPTED),
795  errmsg("index \"%s\" contains corrupted page at block %u",
797  BufferGetBlockNumber(buf)),
798  errhint("Please REINDEX it.")));
799 }
800 
801 
802 /*
803  * Allocate a new page (either by recycling, or by extending the index file)
804  *
805  * The returned buffer is already pinned and exclusive-locked
806  *
807  * Caller is responsible for initializing the page by calling GISTInitBuffer
808  */
809 Buffer
811 {
812  Buffer buffer;
813  bool needLock;
814 
815  /* First, try to get a page from FSM */
816  for (;;)
817  {
819 
820  if (blkno == InvalidBlockNumber)
821  break; /* nothing left in FSM */
822 
823  buffer = ReadBuffer(r, blkno);
824 
825  /*
826  * We have to guard against the possibility that someone else already
827  * recycled this page; the buffer may be locked if so.
828  */
829  if (ConditionalLockBuffer(buffer))
830  {
831  Page page = BufferGetPage(buffer);
832 
833  /*
834  * If the page was never initialized, it's OK to use.
835  */
836  if (PageIsNew(page))
837  return buffer;
838 
839  gistcheckpage(r, buffer);
840 
841  /*
842  * Otherwise, recycle it if deleted, and too old to have any
843  * processes interested in it.
844  */
845  if (gistPageRecyclable(page))
846  {
847  /*
848  * If we are generating WAL for Hot Standby then create a WAL
849  * record that will allow us to conflict with queries running
850  * on standby, in case they have snapshots older than the
851  * page's deleteXid.
852  */
854  gistXLogPageReuse(r, blkno, GistPageGetDeleteXid(page));
855 
856  return buffer;
857  }
858 
859  LockBuffer(buffer, GIST_UNLOCK);
860  }
861 
862  /* Can't use it, so release buffer and try again */
863  ReleaseBuffer(buffer);
864  }
865 
866  /* Must extend the file */
867  needLock = !RELATION_IS_LOCAL(r);
868 
869  if (needLock)
871 
872  buffer = ReadBuffer(r, P_NEW);
873  LockBuffer(buffer, GIST_EXCLUSIVE);
874 
875  if (needLock)
877 
878  return buffer;
879 }
880 
881 /* Can this page be recycled yet? */
882 bool
884 {
885  if (PageIsNew(page))
886  return true;
887  if (GistPageIsDeleted(page))
888  {
889  /*
890  * The page was deleted, but when? If it was just deleted, a scan
891  * might have seen the downlink to it, and will read the page later.
892  * As long as that can happen, we must keep the deleted page around as
893  * a tombstone.
894  *
895  * Compare the deletion XID with RecentGlobalXmin. If deleteXid <
896  * RecentGlobalXmin, then no scan that's still in progress could have
897  * seen its downlink, and we can recycle it.
898  */
899  FullTransactionId deletexid_full = GistPageGetDeleteXid(page);
900  FullTransactionId recentxmin_full = GetFullRecentGlobalXmin();
901 
902  if (FullTransactionIdPrecedes(deletexid_full, recentxmin_full))
903  return true;
904  }
905  return false;
906 }
907 
908 bytea *
909 gistoptions(Datum reloptions, bool validate)
910 {
912  GiSTOptions *rdopts;
913  int numoptions;
914  static const relopt_parse_elt tab[] = {
915  {"fillfactor", RELOPT_TYPE_INT, offsetof(GiSTOptions, fillfactor)},
916  {"buffering", RELOPT_TYPE_ENUM, offsetof(GiSTOptions, buffering_mode)}
917  };
918 
919  options = parseRelOptions(reloptions, validate, RELOPT_KIND_GIST,
920  &numoptions);
921 
922  /* if none set, we're done */
923  if (numoptions == 0)
924  return NULL;
925 
926  rdopts = allocateReloptStruct(sizeof(GiSTOptions), options, numoptions);
927 
928  fillRelOptions((void *) rdopts, sizeof(GiSTOptions), options, numoptions,
929  validate, tab, lengthof(tab));
930 
931  pfree(options);
932 
933  return (bytea *) rdopts;
934 }
935 
936 /*
937  * gistproperty() -- Check boolean properties of indexes.
938  *
939  * This is optional for most AMs, but is required for GiST because the core
940  * property code doesn't support AMPROP_DISTANCE_ORDERABLE. We also handle
941  * AMPROP_RETURNABLE here to save opening the rel to call gistcanreturn.
942  */
943 bool
944 gistproperty(Oid index_oid, int attno,
945  IndexAMProperty prop, const char *propname,
946  bool *res, bool *isnull)
947 {
948  Oid opclass,
949  opfamily,
950  opcintype;
951  int16 procno;
952 
953  /* Only answer column-level inquiries */
954  if (attno == 0)
955  return false;
956 
957  /*
958  * Currently, GiST distance-ordered scans require that there be a distance
959  * function in the opclass with the default types (i.e. the one loaded
960  * into the relcache entry, see initGISTstate). So we assume that if such
961  * a function exists, then there's a reason for it (rather than grubbing
962  * through all the opfamily's operators to find an ordered one).
963  *
964  * Essentially the same code can test whether we support returning the
965  * column data, since that's true if the opclass provides a fetch proc.
966  */
967 
968  switch (prop)
969  {
971  procno = GIST_DISTANCE_PROC;
972  break;
973  case AMPROP_RETURNABLE:
974  procno = GIST_FETCH_PROC;
975  break;
976  default:
977  return false;
978  }
979 
980  /* First we need to know the column's opclass. */
981  opclass = get_index_column_opclass(index_oid, attno);
982  if (!OidIsValid(opclass))
983  {
984  *isnull = true;
985  return true;
986  }
987 
988  /* Now look up the opclass family and input datatype. */
989  if (!get_opclass_opfamily_and_input_type(opclass, &opfamily, &opcintype))
990  {
991  *isnull = true;
992  return true;
993  }
994 
995  /* And now we can check whether the function is provided. */
996 
998  ObjectIdGetDatum(opfamily),
999  ObjectIdGetDatum(opcintype),
1000  ObjectIdGetDatum(opcintype),
1001  Int16GetDatum(procno));
1002 
1003  /*
1004  * Special case: even without a fetch function, AMPROP_RETURNABLE is true
1005  * if the opclass has no compress function.
1006  */
1007  if (prop == AMPROP_RETURNABLE && !*res)
1008  {
1010  ObjectIdGetDatum(opfamily),
1011  ObjectIdGetDatum(opcintype),
1012  ObjectIdGetDatum(opcintype),
1014  }
1015 
1016  *isnull = false;
1017 
1018  return true;
1019 }
1020 
1021 /*
1022  * Temporary and unlogged GiST indexes are not WAL-logged, but we need LSNs
1023  * to detect concurrent page splits anyway. This function provides a fake
1024  * sequence of LSNs for that purpose.
1025  */
1026 XLogRecPtr
1028 {
1029  static XLogRecPtr counter = FirstNormalUnloggedLSN;
1030 
1031  if (rel->rd_rel->relpersistence == RELPERSISTENCE_TEMP)
1032  {
1033  /*
1034  * Temporary relations are only accessible in our session, so a simple
1035  * backend-local counter will do.
1036  */
1037  return counter++;
1038  }
1039  else
1040  {
1041  /*
1042  * Unlogged relations are accessible from other backends, and survive
1043  * (clean) restarts. GetFakeLSNForUnloggedRel() handles that for us.
1044  */
1045  Assert(rel->rd_rel->relpersistence == RELPERSISTENCE_UNLOGGED);
1046  return GetFakeLSNForUnloggedRel();
1047  }
1048 }
Relation rel
Definition: gist.h:132
signed short int16
Definition: c.h:345
static Datum gistFetchAtt(GISTSTATE *giststate, int nkey, Datum k, Relation r)
Definition: gistutil.c:638
#define GistPageIsDeleted(page)
Definition: gist.h:143
#define PageIsEmpty(page)
Definition: bufpage.h:222
int errhint(const char *fmt,...)
Definition: elog.c:974
#define GIST_FETCH_PROC
Definition: gist.h:37
IndexAMProperty
Definition: amapi.h:34
FmgrInfo fetchFn[INDEX_MAX_KEYS]
Definition: gist_private.h:94
#define ExclusiveLock
Definition: lockdefs.h:44
Oid supportCollation[INDEX_MAX_KEYS]
Definition: gist_private.h:97
#define PointerGetDatum(X)
Definition: postgres.h:556
long random(void)
Definition: random.c:22
FmgrInfo compressFn[INDEX_MAX_KEYS]
Definition: gist_private.h:88
void gistDeCompressAtt(GISTSTATE *giststate, Relation r, IndexTuple tuple, Page p, OffsetNumber o, GISTENTRY *attdata, bool *isnull)
Definition: gistutil.c:296
FmgrInfo equalFn[INDEX_MAX_KEYS]
Definition: gist_private.h:92
#define RELATION_IS_LOCAL(relation)
Definition: rel.h:539
ItemPointerData t_tid
Definition: itup.h:37
void gistfillbuffer(Page page, IndexTuple *itup, int len, OffsetNumber off)
Definition: gistutil.c:34
static MemoryContext MemoryContextSwitchTo(MemoryContext context)
Definition: palloc.h:109
#define Int16GetDatum(X)
Definition: postgres.h:451
Pointer Item
Definition: item.h:17
int32 n
Definition: gist.h:206
#define SearchSysCacheExists4(cacheId, key1, key2, key3, key4)
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#define PageAddItem(page, item, size, offsetNumber, overwrite, is_heap)
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#define GIST_UNLOCK
Definition: gist_private.h:44
uint32 BlockNumber
Definition: block.h:31
void ReleaseBuffer(Buffer buffer)
Definition: bufmgr.c:3365
#define P_NEW
Definition: bufmgr.h:81
HeapTuple heap_form_tuple(TupleDesc tupleDescriptor, Datum *values, bool *isnull)
Definition: heaptuple.c:1020
#define lengthof(array)
Definition: c.h:662
Datum FunctionCall2Coll(FmgrInfo *flinfo, Oid collation, Datum arg1, Datum arg2)
Definition: fmgr.c:1150
Form_pg_class rd_rel
Definition: rel.h:83
unsigned int Oid
Definition: postgres_ext.h:31
bytea * gistoptions(Datum reloptions, bool validate)
Definition: gistutil.c:909
#define OidIsValid(objectId)
Definition: c.h:638
#define PageGetMaxOffsetNumber(page)
Definition: bufpage.h:357
IndexTuple gistgetadjusted(Relation r, IndexTuple oldtup, IndexTuple addtup, GISTSTATE *giststate)
Definition: gistutil.c:316
#define fetchatt(A, T)
Definition: tupmacs.h:39
XLogRecPtr gistGetFakeLSN(Relation rel)
Definition: gistutil.c:1027
Size PageGetFreeSpace(Page page)
Definition: bufpage.c:581
bool gistKeyIsEQ(GISTSTATE *giststate, int attno, Datum a, Datum b)
Definition: gistutil.c:281
uint16 OffsetNumber
Definition: off.h:24
Page page
Definition: gist.h:133
GISTENTRY vector[FLEXIBLE_ARRAY_MEMBER]
Definition: gist.h:207
IndexTuple index_form_tuple(TupleDesc tupleDescriptor, Datum *values, bool *isnull)
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bool get_opclass_opfamily_and_input_type(Oid opclass, Oid *opfamily, Oid *opcintype)
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IndexTuple * gistextractpage(Page page, int *len)
Definition: gistutil.c:95
uint16 gist_page_id
Definition: gist.h:71
void pfree(void *pointer)
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#define GEVHDRSZ
Definition: gist.h:210
float gistpenalty(GISTSTATE *giststate, int attno, GISTENTRY *orig, bool isNullOrig, GISTENTRY *add, bool isNullAdd)
Definition: gistutil.c:716
void gistdentryinit(GISTSTATE *giststate, int nkey, GISTENTRY *e, Datum k, Relation r, Page pg, OffsetNumber o, bool l, bool isNull)
Definition: gistutil.c:547
struct GISTENTRY GISTENTRY
#define ObjectIdGetDatum(X)
Definition: postgres.h:507
#define ERROR
Definition: elog.h:43
bool fn_strict
Definition: fmgr.h:61
#define GIST_COMPRESS_PROC
Definition: gist.h:31
int fillfactor
Definition: pgbench.c:157
XLogRecPtr GetFakeLSNForUnloggedRel(void)
Definition: xlog.c:4838
MemoryContext tempCxt
Definition: gist_private.h:78
void gistXLogPageReuse(Relation rel, BlockNumber blkno, FullTransactionId latestRemovedXid)
Definition: gistxlog.c:599
BlockNumber blkno
Definition: ginvacuum.c:119
Datum key
Definition: gist.h:131
void * allocateReloptStruct(Size base, relopt_value *options, int numoptions)
Definition: reloptions.c:1369
static char * buf
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#define memmove(d, s, c)
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#define FirstOffsetNumber
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IndexTupleData * IndexTuple
Definition: itup.h:53
#define MAX_RANDOM_VALUE
bool gistnospace(Page page, IndexTuple *itvec, int len, OffsetNumber todelete, Size freespace)
Definition: gistutil.c:59
#define RelationGetRelationName(relation)
Definition: rel.h:453
FmgrInfo penaltyFn[INDEX_MAX_KEYS]
Definition: gist_private.h:90
unsigned int uint32
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struct ItemIdData ItemIdData
uint16 flags
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#define IndexRelationGetNumberOfKeyAttributes(relation)
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HeapTuple gistFetchTuple(GISTSTATE *giststate, Relation r, IndexTuple tuple)
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#define FirstNormalUnloggedLSN
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#define InvalidOid
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e
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Definition: gist.h:69
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#define GIST_PAGE_ID
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Pointer Page
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