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nbtsplitloc.c
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1 /*-------------------------------------------------------------------------
2  *
3  * nbtsplitloc.c
4  * Choose split point code for Postgres btree implementation.
5  *
6  * Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
7  * Portions Copyright (c) 1994, Regents of the University of California
8  *
9  *
10  * IDENTIFICATION
11  * src/backend/access/nbtree/nbtsplitloc.c
12  *
13  *-------------------------------------------------------------------------
14  */
15 #include "postgres.h"
16 
17 #include "access/nbtree.h"
18 #include "storage/lmgr.h"
19 
20 typedef enum
21 {
22  /* strategy for searching through materialized list of split points */
23  SPLIT_DEFAULT, /* give some weight to truncation */
24  SPLIT_MANY_DUPLICATES, /* find minimally distinguishing point */
25  SPLIT_SINGLE_VALUE /* leave left page almost full */
27 
28 typedef struct
29 {
30  /* details of free space left by split */
31  int16 curdelta; /* current leftfree/rightfree delta */
32  int16 leftfree; /* space left on left page post-split */
33  int16 rightfree; /* space left on right page post-split */
34 
35  /* split point identifying fields (returned by _bt_findsplitloc) */
36  OffsetNumber firstrightoff; /* first origpage item on rightpage */
37  bool newitemonleft; /* new item goes on left, or right? */
38 } SplitPoint;
39 
40 typedef struct
41 {
42  /* context data for _bt_recsplitloc */
43  Relation rel; /* index relation */
44  Page origpage; /* page undergoing split */
45  IndexTuple newitem; /* new item (cause of page split) */
46  Size newitemsz; /* size of newitem (includes line pointer) */
47  bool is_leaf; /* T if splitting a leaf page */
48  bool is_rightmost; /* T if splitting rightmost page on level */
49  OffsetNumber newitemoff; /* where the new item is to be inserted */
50  int leftspace; /* space available for items on left page */
51  int rightspace; /* space available for items on right page */
52  int olddataitemstotal; /* space taken by old items */
53  Size minfirstrightsz; /* smallest firstright size */
54 
55  /* candidate split point data */
56  int maxsplits; /* maximum number of splits */
57  int nsplits; /* current number of splits */
58  SplitPoint *splits; /* all candidate split points for page */
59  int interval; /* current range of acceptable split points */
61 
63  OffsetNumber firstrightoff, bool newitemonleft,
64  int olddataitemstoleft,
65  Size firstrightofforigpagetuplesz);
66 static void _bt_deltasortsplits(FindSplitData *state, double fillfactormult,
67  bool usemult);
68 static int _bt_splitcmp(const void *arg1, const void *arg2);
70  int leaffillfactor, bool *usemult);
71 static bool _bt_adjacenthtid(ItemPointer lowhtid, ItemPointer highhtid);
72 static OffsetNumber _bt_bestsplitloc(FindSplitData *state, int perfectpenalty,
73  bool *newitemonleft, FindSplitStrat strategy);
75 static int _bt_strategy(FindSplitData *state, SplitPoint *leftpage,
76  SplitPoint *rightpage, FindSplitStrat *strategy);
78  SplitPoint **leftinterval, SplitPoint **rightinterval);
79 static inline int _bt_split_penalty(FindSplitData *state, SplitPoint *split);
81  SplitPoint *split);
83  SplitPoint *split);
84 
85 
86 /*
87  * _bt_findsplitloc() -- find an appropriate place to split a page.
88  *
89  * The main goal here is to equalize the free space that will be on each
90  * split page, *after accounting for the inserted tuple*. (If we fail to
91  * account for it, we might find ourselves with too little room on the page
92  * that it needs to go into!)
93  *
94  * If the page is the rightmost page on its level, we instead try to arrange
95  * to leave the left split page fillfactor% full. In this way, when we are
96  * inserting successively increasing keys (consider sequences, timestamps,
97  * etc) we will end up with a tree whose pages are about fillfactor% full,
98  * instead of the 50% full result that we'd get without this special case.
99  * This is the same as nbtsort.c produces for a newly-created tree. Note
100  * that leaf and nonleaf pages use different fillfactors. Note also that
101  * there are a number of further special cases where fillfactor is not
102  * applied in the standard way.
103  *
104  * We are passed the intended insert position of the new tuple, expressed as
105  * the offsetnumber of the tuple it must go in front of (this could be
106  * maxoff+1 if the tuple is to go at the end). The new tuple itself is also
107  * passed, since it's needed to give some weight to how effective suffix
108  * truncation will be. The implementation picks the split point that
109  * maximizes the effectiveness of suffix truncation from a small list of
110  * alternative candidate split points that leave each side of the split with
111  * about the same share of free space. Suffix truncation is secondary to
112  * equalizing free space, except in cases with large numbers of duplicates.
113  * Note that it is always assumed that caller goes on to perform truncation,
114  * even with pg_upgrade'd indexes where that isn't actually the case
115  * (!heapkeyspace indexes). See nbtree/README for more information about
116  * suffix truncation.
117  *
118  * We return the index of the first existing tuple that should go on the
119  * righthand page (which is called firstrightoff), plus a boolean
120  * indicating whether the new tuple goes on the left or right page. You
121  * can think of the returned state as a point _between_ two adjacent data
122  * items (laftleft and firstright data items) on an imaginary version of
123  * origpage that already includes newitem. The bool is necessary to
124  * disambiguate the case where firstrightoff == newitemoff (i.e. it is
125  * sometimes needed to determine if the firstright tuple for the split is
126  * newitem rather than the tuple from origpage at offset firstrightoff).
127  */
130  Page origpage,
131  OffsetNumber newitemoff,
132  Size newitemsz,
133  IndexTuple newitem,
134  bool *newitemonleft)
135 {
136  BTPageOpaque opaque;
137  int leftspace,
138  rightspace,
139  olddataitemstotal,
140  olddataitemstoleft,
141  perfectpenalty,
142  leaffillfactor;
144  FindSplitStrat strategy;
145  ItemId itemid;
146  OffsetNumber offnum,
147  maxoff,
148  firstrightoff;
149  double fillfactormult;
150  bool usemult;
151  SplitPoint leftpage,
152  rightpage;
153 
154  opaque = BTPageGetOpaque(origpage);
155  maxoff = PageGetMaxOffsetNumber(origpage);
156 
157  /* Total free space available on a btree page, after fixed overhead */
158  leftspace = rightspace =
160  MAXALIGN(sizeof(BTPageOpaqueData));
161 
162  /* The right page will have the same high key as the old page */
163  if (!P_RIGHTMOST(opaque))
164  {
165  itemid = PageGetItemId(origpage, P_HIKEY);
166  rightspace -= (int) (MAXALIGN(ItemIdGetLength(itemid)) +
167  sizeof(ItemIdData));
168  }
169 
170  /* Count up total space in data items before actually scanning 'em */
171  olddataitemstotal = rightspace - (int) PageGetExactFreeSpace(origpage);
172  leaffillfactor = BTGetFillFactor(rel);
173 
174  /* Passed-in newitemsz is MAXALIGNED but does not include line pointer */
175  newitemsz += sizeof(ItemIdData);
176  state.rel = rel;
177  state.origpage = origpage;
178  state.newitem = newitem;
179  state.newitemsz = newitemsz;
180  state.is_leaf = P_ISLEAF(opaque);
181  state.is_rightmost = P_RIGHTMOST(opaque);
182  state.leftspace = leftspace;
183  state.rightspace = rightspace;
184  state.olddataitemstotal = olddataitemstotal;
185  state.minfirstrightsz = SIZE_MAX;
186  state.newitemoff = newitemoff;
187 
188  /* newitem cannot be a posting list item */
189  Assert(!BTreeTupleIsPosting(newitem));
190 
191  /*
192  * nsplits should never exceed maxoff because there will be at most as
193  * many candidate split points as there are points _between_ tuples, once
194  * you imagine that the new item is already on the original page (the
195  * final number of splits may be slightly lower because not all points
196  * between tuples will be legal).
197  */
198  state.maxsplits = maxoff;
199  state.splits = palloc(sizeof(SplitPoint) * state.maxsplits);
200  state.nsplits = 0;
201 
202  /*
203  * Scan through the data items and calculate space usage for a split at
204  * each possible position
205  */
206  olddataitemstoleft = 0;
207 
208  for (offnum = P_FIRSTDATAKEY(opaque);
209  offnum <= maxoff;
210  offnum = OffsetNumberNext(offnum))
211  {
212  Size itemsz;
213 
214  itemid = PageGetItemId(origpage, offnum);
215  itemsz = MAXALIGN(ItemIdGetLength(itemid)) + sizeof(ItemIdData);
216 
217  /*
218  * When item offset number is not newitemoff, neither side of the
219  * split can be newitem. Record a split after the previous data item
220  * from original page, but before the current data item from original
221  * page. (_bt_recsplitloc() will reject the split when there are no
222  * previous items, which we rely on.)
223  */
224  if (offnum < newitemoff)
225  _bt_recsplitloc(&state, offnum, false, olddataitemstoleft, itemsz);
226  else if (offnum > newitemoff)
227  _bt_recsplitloc(&state, offnum, true, olddataitemstoleft, itemsz);
228  else
229  {
230  /*
231  * Record a split after all "offnum < newitemoff" original page
232  * data items, but before newitem
233  */
234  _bt_recsplitloc(&state, offnum, false, olddataitemstoleft, itemsz);
235 
236  /*
237  * Record a split after newitem, but before data item from
238  * original page at offset newitemoff/current offset
239  */
240  _bt_recsplitloc(&state, offnum, true, olddataitemstoleft, itemsz);
241  }
242 
243  olddataitemstoleft += itemsz;
244  }
245 
246  /*
247  * Record a split after all original page data items, but before newitem.
248  * (Though only when it's possible that newitem will end up alone on new
249  * right page.)
250  */
251  Assert(olddataitemstoleft == olddataitemstotal);
252  if (newitemoff > maxoff)
253  _bt_recsplitloc(&state, newitemoff, false, olddataitemstotal, 0);
254 
255  /*
256  * I believe it is not possible to fail to find a feasible split, but just
257  * in case ...
258  */
259  if (state.nsplits == 0)
260  elog(ERROR, "could not find a feasible split point for index \"%s\"",
262 
263  /*
264  * Start search for a split point among list of legal split points. Give
265  * primary consideration to equalizing available free space in each half
266  * of the split initially (start with default strategy), while applying
267  * rightmost and split-after-new-item optimizations where appropriate.
268  * Either of the two other fallback strategies may be required for cases
269  * with a large number of duplicates around the original/space-optimal
270  * split point.
271  *
272  * Default strategy gives some weight to suffix truncation in deciding a
273  * split point on leaf pages. It attempts to select a split point where a
274  * distinguishing attribute appears earlier in the new high key for the
275  * left side of the split, in order to maximize the number of trailing
276  * attributes that can be truncated away. Only candidate split points
277  * that imply an acceptable balance of free space on each side are
278  * considered. See _bt_defaultinterval().
279  */
280  if (!state.is_leaf)
281  {
282  /* fillfactormult only used on rightmost page */
283  usemult = state.is_rightmost;
284  fillfactormult = BTREE_NONLEAF_FILLFACTOR / 100.0;
285  }
286  else if (state.is_rightmost)
287  {
288  /* Rightmost leaf page -- fillfactormult always used */
289  usemult = true;
290  fillfactormult = leaffillfactor / 100.0;
291  }
292  else if (_bt_afternewitemoff(&state, maxoff, leaffillfactor, &usemult))
293  {
294  /*
295  * New item inserted at rightmost point among a localized grouping on
296  * a leaf page -- apply "split after new item" optimization, either by
297  * applying leaf fillfactor multiplier, or by choosing the exact split
298  * point that leaves newitem as lastleft. (usemult is set for us.)
299  */
300  if (usemult)
301  {
302  /* fillfactormult should be set based on leaf fillfactor */
303  fillfactormult = leaffillfactor / 100.0;
304  }
305  else
306  {
307  /* find precise split point after newitemoff */
308  for (int i = 0; i < state.nsplits; i++)
309  {
310  SplitPoint *split = state.splits + i;
311 
312  if (split->newitemonleft &&
313  newitemoff == split->firstrightoff)
314  {
315  pfree(state.splits);
316  *newitemonleft = true;
317  return newitemoff;
318  }
319  }
320 
321  /*
322  * Cannot legally split after newitemoff; proceed with split
323  * without using fillfactor multiplier. This is defensive, and
324  * should never be needed in practice.
325  */
326  fillfactormult = 0.50;
327  }
328  }
329  else
330  {
331  /* Other leaf page. 50:50 page split. */
332  usemult = false;
333  /* fillfactormult not used, but be tidy */
334  fillfactormult = 0.50;
335  }
336 
337  /*
338  * Save leftmost and rightmost splits for page before original ordinal
339  * sort order is lost by delta/fillfactormult sort
340  */
341  leftpage = state.splits[0];
342  rightpage = state.splits[state.nsplits - 1];
343 
344  /* Give split points a fillfactormult-wise delta, and sort on deltas */
345  _bt_deltasortsplits(&state, fillfactormult, usemult);
346 
347  /* Determine split interval for default strategy */
348  state.interval = _bt_defaultinterval(&state);
349 
350  /*
351  * Determine if default strategy/split interval will produce a
352  * sufficiently distinguishing split, or if we should change strategies.
353  * Alternative strategies change the range of split points that are
354  * considered acceptable (split interval), and possibly change
355  * fillfactormult, in order to deal with pages with a large number of
356  * duplicates gracefully.
357  *
358  * Pass low and high splits for the entire page (actually, they're for an
359  * imaginary version of the page that includes newitem). These are used
360  * when the initial split interval encloses split points that are full of
361  * duplicates, and we need to consider if it's even possible to avoid
362  * appending a heap TID.
363  */
364  perfectpenalty = _bt_strategy(&state, &leftpage, &rightpage, &strategy);
365 
366  if (strategy == SPLIT_DEFAULT)
367  {
368  /*
369  * Default strategy worked out (always works out with internal page).
370  * Original split interval still stands.
371  */
372  }
373 
374  /*
375  * Many duplicates strategy is used when a heap TID would otherwise be
376  * appended, but the page isn't completely full of logical duplicates.
377  *
378  * The split interval is widened to include all legal candidate split
379  * points. There might be a few as two distinct values in the whole-page
380  * split interval, though it's also possible that most of the values on
381  * the page are unique. The final split point will either be to the
382  * immediate left or to the immediate right of the group of duplicate
383  * tuples that enclose the first/delta-optimal split point (perfect
384  * penalty was set so that the lowest delta split point that avoids
385  * appending a heap TID will be chosen). Maximizing the number of
386  * attributes that can be truncated away is not a goal of the many
387  * duplicates strategy.
388  *
389  * Single value strategy is used when it is impossible to avoid appending
390  * a heap TID. It arranges to leave the left page very full. This
391  * maximizes space utilization in cases where tuples with the same
392  * attribute values span many pages. Newly inserted duplicates will tend
393  * to have higher heap TID values, so we'll end up splitting to the right
394  * consistently. (Single value strategy is harmless though not
395  * particularly useful with !heapkeyspace indexes.)
396  */
397  else if (strategy == SPLIT_MANY_DUPLICATES)
398  {
399  Assert(state.is_leaf);
400  /* Shouldn't try to truncate away extra user attributes */
401  Assert(perfectpenalty ==
403  /* No need to resort splits -- no change in fillfactormult/deltas */
404  state.interval = state.nsplits;
405  }
406  else if (strategy == SPLIT_SINGLE_VALUE)
407  {
408  Assert(state.is_leaf);
409  /* Split near the end of the page */
410  usemult = true;
411  fillfactormult = BTREE_SINGLEVAL_FILLFACTOR / 100.0;
412  /* Resort split points with new delta */
413  _bt_deltasortsplits(&state, fillfactormult, usemult);
414  /* Appending a heap TID is unavoidable, so interval of 1 is fine */
415  state.interval = 1;
416  }
417 
418  /*
419  * Search among acceptable split points (using final split interval) for
420  * the entry that has the lowest penalty, and is therefore expected to
421  * maximize fan-out. Sets *newitemonleft for us.
422  */
423  firstrightoff = _bt_bestsplitloc(&state, perfectpenalty, newitemonleft,
424  strategy);
425  pfree(state.splits);
426 
427  return firstrightoff;
428 }
429 
430 /*
431  * Subroutine to record a particular point between two tuples (possibly the
432  * new item) on page (ie, combination of firstrightoff and newitemonleft
433  * settings) in *state for later analysis. This is also a convenient point to
434  * check if the split is legal (if it isn't, it won't be recorded).
435  *
436  * firstrightoff is the offset of the first item on the original page that
437  * goes to the right page, and firstrightofforigpagetuplesz is the size of
438  * that tuple. firstrightoff can be > max offset, which means that all the
439  * old items go to the left page and only the new item goes to the right page.
440  * We don't actually use firstrightofforigpagetuplesz in that case (actually,
441  * we don't use it for _any_ split where the firstright tuple happens to be
442  * newitem).
443  *
444  * olddataitemstoleft is the total size of all old items to the left of the
445  * split point that is recorded here when legal. Should not include
446  * newitemsz, since that is handled here.
447  */
448 static void
450  OffsetNumber firstrightoff,
451  bool newitemonleft,
452  int olddataitemstoleft,
453  Size firstrightofforigpagetuplesz)
454 {
455  int16 leftfree,
456  rightfree;
457  Size firstrightsz;
458  Size postingsz = 0;
459  bool newitemisfirstright;
460 
461  /* Is the new item going to be split point's firstright tuple? */
462  newitemisfirstright = (firstrightoff == state->newitemoff &&
463  !newitemonleft);
464 
465  if (newitemisfirstright)
466  firstrightsz = state->newitemsz;
467  else
468  {
469  firstrightsz = firstrightofforigpagetuplesz;
470 
471  /*
472  * Calculate suffix truncation space saving when firstright tuple is a
473  * posting list tuple, though only when the tuple is over 64 bytes
474  * including line pointer overhead (arbitrary). This avoids accessing
475  * the tuple in cases where its posting list must be very small (if
476  * tuple has one at all).
477  *
478  * Note: We don't do this in the case where firstright tuple is
479  * newitem, since newitem cannot have a posting list.
480  */
481  if (state->is_leaf && firstrightsz > 64)
482  {
483  ItemId itemid;
484  IndexTuple newhighkey;
485 
486  itemid = PageGetItemId(state->origpage, firstrightoff);
487  newhighkey = (IndexTuple) PageGetItem(state->origpage, itemid);
488 
489  if (BTreeTupleIsPosting(newhighkey))
490  postingsz = IndexTupleSize(newhighkey) -
491  BTreeTupleGetPostingOffset(newhighkey);
492  }
493  }
494 
495  /* Account for all the old tuples */
496  leftfree = state->leftspace - olddataitemstoleft;
497  rightfree = state->rightspace -
498  (state->olddataitemstotal - olddataitemstoleft);
499 
500  /*
501  * The first item on the right page becomes the high key of the left page;
502  * therefore it counts against left space as well as right space (we
503  * cannot assume that suffix truncation will make it any smaller). When
504  * index has included attributes, then those attributes of left page high
505  * key will be truncated leaving that page with slightly more free space.
506  * However, that shouldn't affect our ability to find valid split
507  * location, since we err in the direction of being pessimistic about free
508  * space on the left half. Besides, even when suffix truncation of
509  * non-TID attributes occurs, the new high key often won't even be a
510  * single MAXALIGN() quantum smaller than the firstright tuple it's based
511  * on.
512  *
513  * If we are on the leaf level, assume that suffix truncation cannot avoid
514  * adding a heap TID to the left half's new high key when splitting at the
515  * leaf level. In practice the new high key will often be smaller and
516  * will rarely be larger, but conservatively assume the worst case. We do
517  * go to the trouble of subtracting away posting list overhead, though
518  * only when it looks like it will make an appreciable difference.
519  * (Posting lists are the only case where truncation will typically make
520  * the final high key far smaller than firstright, so being a bit more
521  * precise there noticeably improves the balance of free space.)
522  */
523  if (state->is_leaf)
524  leftfree -= (int16) (firstrightsz +
525  MAXALIGN(sizeof(ItemPointerData)) -
526  postingsz);
527  else
528  leftfree -= (int16) firstrightsz;
529 
530  /* account for the new item */
531  if (newitemonleft)
532  leftfree -= (int16) state->newitemsz;
533  else
534  rightfree -= (int16) state->newitemsz;
535 
536  /*
537  * If we are not on the leaf level, we will be able to discard the key
538  * data from the first item that winds up on the right page.
539  */
540  if (!state->is_leaf)
541  rightfree += (int16) firstrightsz -
542  (int16) (MAXALIGN(sizeof(IndexTupleData)) + sizeof(ItemIdData));
543 
544  /* Record split if legal */
545  if (leftfree >= 0 && rightfree >= 0)
546  {
547  Assert(state->nsplits < state->maxsplits);
548 
549  /* Determine smallest firstright tuple size among legal splits */
550  state->minfirstrightsz = Min(state->minfirstrightsz, firstrightsz);
551 
552  state->splits[state->nsplits].curdelta = 0;
553  state->splits[state->nsplits].leftfree = leftfree;
554  state->splits[state->nsplits].rightfree = rightfree;
555  state->splits[state->nsplits].firstrightoff = firstrightoff;
556  state->splits[state->nsplits].newitemonleft = newitemonleft;
557  state->nsplits++;
558  }
559 }
560 
561 /*
562  * Subroutine to assign space deltas to materialized array of candidate split
563  * points based on current fillfactor, and to sort array using that fillfactor
564  */
565 static void
566 _bt_deltasortsplits(FindSplitData *state, double fillfactormult,
567  bool usemult)
568 {
569  for (int i = 0; i < state->nsplits; i++)
570  {
571  SplitPoint *split = state->splits + i;
572  int16 delta;
573 
574  if (usemult)
575  delta = fillfactormult * split->leftfree -
576  (1.0 - fillfactormult) * split->rightfree;
577  else
578  delta = split->leftfree - split->rightfree;
579 
580  if (delta < 0)
581  delta = -delta;
582 
583  /* Save delta */
584  split->curdelta = delta;
585  }
586 
587  qsort(state->splits, state->nsplits, sizeof(SplitPoint), _bt_splitcmp);
588 }
589 
590 /*
591  * qsort-style comparator used by _bt_deltasortsplits()
592  */
593 static int
594 _bt_splitcmp(const void *arg1, const void *arg2)
595 {
596  SplitPoint *split1 = (SplitPoint *) arg1;
597  SplitPoint *split2 = (SplitPoint *) arg2;
598 
599  if (split1->curdelta > split2->curdelta)
600  return 1;
601  if (split1->curdelta < split2->curdelta)
602  return -1;
603 
604  return 0;
605 }
606 
607 /*
608  * Subroutine to determine whether or not a non-rightmost leaf page should be
609  * split immediately after the would-be original page offset for the
610  * new/incoming tuple (or should have leaf fillfactor applied when new item is
611  * to the right on original page). This is appropriate when there is a
612  * pattern of localized monotonically increasing insertions into a composite
613  * index, where leading attribute values form local groupings, and we
614  * anticipate further insertions of the same/current grouping (new item's
615  * grouping) in the near future. This can be thought of as a variation on
616  * applying leaf fillfactor during rightmost leaf page splits, since cases
617  * that benefit will converge on packing leaf pages leaffillfactor% full over
618  * time.
619  *
620  * We may leave extra free space remaining on the rightmost page of a "most
621  * significant column" grouping of tuples if that grouping never ends up
622  * having future insertions that use the free space. That effect is
623  * self-limiting; a future grouping that becomes the "nearest on the right"
624  * grouping of the affected grouping usually puts the extra free space to good
625  * use.
626  *
627  * Caller uses optimization when routine returns true, though the exact action
628  * taken by caller varies. Caller uses original leaf page fillfactor in
629  * standard way rather than using the new item offset directly when *usemult
630  * was also set to true here. Otherwise, caller applies optimization by
631  * locating the legal split point that makes the new tuple the lastleft tuple
632  * for the split.
633  */
634 static bool
636  int leaffillfactor, bool *usemult)
637 {
638  int16 nkeyatts;
639  ItemId itemid;
640  IndexTuple tup;
641  int keepnatts;
642 
643  Assert(state->is_leaf && !state->is_rightmost);
644 
646 
647  /* Single key indexes not considered here */
648  if (nkeyatts == 1)
649  return false;
650 
651  /* Ascending insertion pattern never inferred when new item is first */
652  if (state->newitemoff == P_FIRSTKEY)
653  return false;
654 
655  /*
656  * Only apply optimization on pages with equisized tuples, since ordinal
657  * keys are likely to be fixed-width. Testing if the new tuple is
658  * variable width directly might also work, but that fails to apply the
659  * optimization to indexes with a numeric_ops attribute.
660  *
661  * Conclude that page has equisized tuples when the new item is the same
662  * width as the smallest item observed during pass over page, and other
663  * non-pivot tuples must be the same width as well. (Note that the
664  * possibly-truncated existing high key isn't counted in
665  * olddataitemstotal, and must be subtracted from maxoff.)
666  */
667  if (state->newitemsz != state->minfirstrightsz)
668  return false;
669  if (state->newitemsz * (maxoff - 1) != state->olddataitemstotal)
670  return false;
671 
672  /*
673  * Avoid applying optimization when tuples are wider than a tuple
674  * consisting of two non-NULL int8/int64 attributes (or four non-NULL
675  * int4/int32 attributes)
676  */
677  if (state->newitemsz >
678  MAXALIGN(sizeof(IndexTupleData) + sizeof(int64) * 2) +
679  sizeof(ItemIdData))
680  return false;
681 
682  /*
683  * At least the first attribute's value must be equal to the corresponding
684  * value in previous tuple to apply optimization. New item cannot be a
685  * duplicate, either.
686  *
687  * Handle case where new item is to the right of all items on the existing
688  * page. This is suggestive of monotonically increasing insertions in
689  * itself, so the "heap TID adjacency" test is not applied here.
690  */
691  if (state->newitemoff > maxoff)
692  {
693  itemid = PageGetItemId(state->origpage, maxoff);
694  tup = (IndexTuple) PageGetItem(state->origpage, itemid);
695  keepnatts = _bt_keep_natts_fast(state->rel, tup, state->newitem);
696 
697  if (keepnatts > 1 && keepnatts <= nkeyatts)
698  {
699  *usemult = true;
700  return true;
701  }
702 
703  return false;
704  }
705 
706  /*
707  * "Low cardinality leading column, high cardinality suffix column"
708  * indexes with a random insertion pattern (e.g., an index with a boolean
709  * column, such as an index on '(book_is_in_print, book_isbn)') present us
710  * with a risk of consistently misapplying the optimization. We're
711  * willing to accept very occasional misapplication of the optimization,
712  * provided the cases where we get it wrong are rare and self-limiting.
713  *
714  * Heap TID adjacency strongly suggests that the item just to the left was
715  * inserted very recently, which limits overapplication of the
716  * optimization. Besides, all inappropriate cases triggered here will
717  * still split in the middle of the page on average.
718  */
719  itemid = PageGetItemId(state->origpage, OffsetNumberPrev(state->newitemoff));
720  tup = (IndexTuple) PageGetItem(state->origpage, itemid);
721  /* Do cheaper test first */
722  if (BTreeTupleIsPosting(tup) ||
723  !_bt_adjacenthtid(&tup->t_tid, &state->newitem->t_tid))
724  return false;
725  /* Check same conditions as rightmost item case, too */
726  keepnatts = _bt_keep_natts_fast(state->rel, tup, state->newitem);
727 
728  if (keepnatts > 1 && keepnatts <= nkeyatts)
729  {
730  double interp = (double) state->newitemoff / ((double) maxoff + 1);
731  double leaffillfactormult = (double) leaffillfactor / 100.0;
732 
733  /*
734  * Don't allow caller to split after a new item when it will result in
735  * a split point to the right of the point that a leaf fillfactor
736  * split would use -- have caller apply leaf fillfactor instead
737  */
738  *usemult = interp > leaffillfactormult;
739 
740  return true;
741  }
742 
743  return false;
744 }
745 
746 /*
747  * Subroutine for determining if two heap TIDS are "adjacent".
748  *
749  * Adjacent means that the high TID is very likely to have been inserted into
750  * heap relation immediately after the low TID, probably during the current
751  * transaction.
752  */
753 static bool
755 {
756  BlockNumber lowblk,
757  highblk;
758 
759  lowblk = ItemPointerGetBlockNumber(lowhtid);
760  highblk = ItemPointerGetBlockNumber(highhtid);
761 
762  /* Make optimistic assumption of adjacency when heap blocks match */
763  if (lowblk == highblk)
764  return true;
765 
766  /* When heap block one up, second offset should be FirstOffsetNumber */
767  if (lowblk + 1 == highblk &&
769  return true;
770 
771  return false;
772 }
773 
774 /*
775  * Subroutine to find the "best" split point among candidate split points.
776  * The best split point is the split point with the lowest penalty among split
777  * points that fall within current/final split interval. Penalty is an
778  * abstract score, with a definition that varies depending on whether we're
779  * splitting a leaf page or an internal page. See _bt_split_penalty() for
780  * details.
781  *
782  * "perfectpenalty" is assumed to be the lowest possible penalty among
783  * candidate split points. This allows us to return early without wasting
784  * cycles on calculating the first differing attribute for all candidate
785  * splits when that clearly cannot improve our choice (or when we only want a
786  * minimally distinguishing split point, and don't want to make the split any
787  * more unbalanced than is necessary).
788  *
789  * We return the index of the first existing tuple that should go on the right
790  * page, plus a boolean indicating if new item is on left of split point.
791  */
792 static OffsetNumber
793 _bt_bestsplitloc(FindSplitData *state, int perfectpenalty,
794  bool *newitemonleft, FindSplitStrat strategy)
795 {
796  int bestpenalty,
797  lowsplit;
798  int highsplit = Min(state->interval, state->nsplits);
799  SplitPoint *final;
800 
801  bestpenalty = INT_MAX;
802  lowsplit = 0;
803  for (int i = lowsplit; i < highsplit; i++)
804  {
805  int penalty;
806 
807  penalty = _bt_split_penalty(state, state->splits + i);
808 
809  if (penalty < bestpenalty)
810  {
811  bestpenalty = penalty;
812  lowsplit = i;
813  }
814 
815  if (penalty <= perfectpenalty)
816  break;
817  }
818 
819  final = &state->splits[lowsplit];
820 
821  /*
822  * There is a risk that the "many duplicates" strategy will repeatedly do
823  * the wrong thing when there are monotonically decreasing insertions to
824  * the right of a large group of duplicates. Repeated splits could leave
825  * a succession of right half pages with free space that can never be
826  * used. This must be avoided.
827  *
828  * Consider the example of the leftmost page in a single integer attribute
829  * NULLS FIRST index which is almost filled with NULLs. Monotonically
830  * decreasing integer insertions might cause the same leftmost page to
831  * split repeatedly at the same point. Each split derives its new high
832  * key from the lowest current value to the immediate right of the large
833  * group of NULLs, which will always be higher than all future integer
834  * insertions, directing all future integer insertions to the same
835  * leftmost page.
836  */
837  if (strategy == SPLIT_MANY_DUPLICATES && !state->is_rightmost &&
838  !final->newitemonleft && final->firstrightoff >= state->newitemoff &&
839  final->firstrightoff < state->newitemoff + 9)
840  {
841  /*
842  * Avoid the problem by performing a 50:50 split when the new item is
843  * just to the right of the would-be "many duplicates" split point.
844  * (Note that the test used for an insert that is "just to the right"
845  * of the split point is conservative.)
846  */
847  final = &state->splits[0];
848  }
849 
850  *newitemonleft = final->newitemonleft;
851  return final->firstrightoff;
852 }
853 
854 #define LEAF_SPLIT_DISTANCE 0.050
855 #define INTERNAL_SPLIT_DISTANCE 0.075
856 
857 /*
858  * Return a split interval to use for the default strategy. This is a limit
859  * on the number of candidate split points to give further consideration to.
860  * Only a fraction of all candidate splits points (those located at the start
861  * of the now-sorted splits array) fall within the split interval. Split
862  * interval is applied within _bt_bestsplitloc().
863  *
864  * Split interval represents an acceptable range of split points -- those that
865  * have leftfree and rightfree values that are acceptably balanced. The final
866  * split point chosen is the split point with the lowest "penalty" among split
867  * points in this split interval (unless we change our entire strategy, in
868  * which case the interval also changes -- see _bt_strategy()).
869  *
870  * The "Prefix B-Trees" paper calls split interval sigma l for leaf splits,
871  * and sigma b for internal ("branch") splits. It's hard to provide a
872  * theoretical justification for the size of the split interval, though it's
873  * clear that a small split interval can make tuples on level L+1 much smaller
874  * on average, without noticeably affecting space utilization on level L.
875  * (Note that the way that we calculate split interval might need to change if
876  * suffix truncation is taught to truncate tuples "within" the last
877  * attribute/datum for data types like text, which is more or less how it is
878  * assumed to work in the paper.)
879  */
880 static int
882 {
883  SplitPoint *spaceoptimal;
884  int16 tolerance,
885  lowleftfree,
886  lowrightfree,
887  highleftfree,
888  highrightfree;
889 
890  /*
891  * Determine leftfree and rightfree values that are higher and lower than
892  * we're willing to tolerate. Note that the final split interval will be
893  * about 10% of nsplits in the common case where all non-pivot tuples
894  * (data items) from a leaf page are uniformly sized. We're a bit more
895  * aggressive when splitting internal pages.
896  */
897  if (state->is_leaf)
898  tolerance = state->olddataitemstotal * LEAF_SPLIT_DISTANCE;
899  else
900  tolerance = state->olddataitemstotal * INTERNAL_SPLIT_DISTANCE;
901 
902  /* First candidate split point is the most evenly balanced */
903  spaceoptimal = state->splits;
904  lowleftfree = spaceoptimal->leftfree - tolerance;
905  lowrightfree = spaceoptimal->rightfree - tolerance;
906  highleftfree = spaceoptimal->leftfree + tolerance;
907  highrightfree = spaceoptimal->rightfree + tolerance;
908 
909  /*
910  * Iterate through split points, starting from the split immediately after
911  * 'spaceoptimal'. Find the first split point that divides free space so
912  * unevenly that including it in the split interval would be unacceptable.
913  */
914  for (int i = 1; i < state->nsplits; i++)
915  {
916  SplitPoint *split = state->splits + i;
917 
918  /* Cannot use curdelta here, since its value is often weighted */
919  if (split->leftfree < lowleftfree || split->rightfree < lowrightfree ||
920  split->leftfree > highleftfree || split->rightfree > highrightfree)
921  return i;
922  }
923 
924  return state->nsplits;
925 }
926 
927 /*
928  * Subroutine to decide whether split should use default strategy/initial
929  * split interval, or whether it should finish splitting the page using
930  * alternative strategies (this is only possible with leaf pages).
931  *
932  * Caller uses alternative strategy (or sticks with default strategy) based
933  * on how *strategy is set here. Return value is "perfect penalty", which is
934  * passed to _bt_bestsplitloc() as a final constraint on how far caller is
935  * willing to go to avoid appending a heap TID when using the many duplicates
936  * strategy (it also saves _bt_bestsplitloc() useless cycles).
937  */
938 static int
940  SplitPoint *rightpage, FindSplitStrat *strategy)
941 {
942  IndexTuple leftmost,
943  rightmost;
944  SplitPoint *leftinterval,
945  *rightinterval;
946  int perfectpenalty;
947  int indnkeyatts = IndexRelationGetNumberOfKeyAttributes(state->rel);
948 
949  /* Assume that alternative strategy won't be used for now */
950  *strategy = SPLIT_DEFAULT;
951 
952  /*
953  * Use smallest observed firstright item size for entire page (actually,
954  * entire imaginary version of page that includes newitem) as perfect
955  * penalty on internal pages. This can save cycles in the common case
956  * where most or all splits (not just splits within interval) have
957  * firstright tuples that are the same size.
958  */
959  if (!state->is_leaf)
960  return state->minfirstrightsz;
961 
962  /*
963  * Use leftmost and rightmost tuples from leftmost and rightmost splits in
964  * current split interval
965  */
966  _bt_interval_edges(state, &leftinterval, &rightinterval);
967  leftmost = _bt_split_lastleft(state, leftinterval);
968  rightmost = _bt_split_firstright(state, rightinterval);
969 
970  /*
971  * If initial split interval can produce a split point that will at least
972  * avoid appending a heap TID in new high key, we're done. Finish split
973  * with default strategy and initial split interval.
974  */
975  perfectpenalty = _bt_keep_natts_fast(state->rel, leftmost, rightmost);
976  if (perfectpenalty <= indnkeyatts)
977  return perfectpenalty;
978 
979  /*
980  * Work out how caller should finish split when even their "perfect"
981  * penalty for initial/default split interval indicates that the interval
982  * does not contain even a single split that avoids appending a heap TID.
983  *
984  * Use the leftmost split's lastleft tuple and the rightmost split's
985  * firstright tuple to assess every possible split.
986  */
987  leftmost = _bt_split_lastleft(state, leftpage);
988  rightmost = _bt_split_firstright(state, rightpage);
989 
990  /*
991  * If page (including new item) has many duplicates but is not entirely
992  * full of duplicates, a many duplicates strategy split will be performed.
993  * If page is entirely full of duplicates, a single value strategy split
994  * will be performed.
995  */
996  perfectpenalty = _bt_keep_natts_fast(state->rel, leftmost, rightmost);
997  if (perfectpenalty <= indnkeyatts)
998  {
999  *strategy = SPLIT_MANY_DUPLICATES;
1000 
1001  /*
1002  * Many duplicates strategy should split at either side the group of
1003  * duplicates that enclose the delta-optimal split point. Return
1004  * indnkeyatts rather than the true perfect penalty to make that
1005  * happen. (If perfectpenalty was returned here then low cardinality
1006  * composite indexes could have continual unbalanced splits.)
1007  *
1008  * Note that caller won't go through with a many duplicates split in
1009  * rare cases where it looks like there are ever-decreasing insertions
1010  * to the immediate right of the split point. This must happen just
1011  * before a final decision is made, within _bt_bestsplitloc().
1012  */
1013  return indnkeyatts;
1014  }
1015 
1016  /*
1017  * Single value strategy is only appropriate with ever-increasing heap
1018  * TIDs; otherwise, original default strategy split should proceed to
1019  * avoid pathological performance. Use page high key to infer if this is
1020  * the rightmost page among pages that store the same duplicate value.
1021  * This should not prevent insertions of heap TIDs that are slightly out
1022  * of order from using single value strategy, since that's expected with
1023  * concurrent inserters of the same duplicate value.
1024  */
1025  else if (state->is_rightmost)
1026  *strategy = SPLIT_SINGLE_VALUE;
1027  else
1028  {
1029  ItemId itemid;
1030  IndexTuple hikey;
1031 
1032  itemid = PageGetItemId(state->origpage, P_HIKEY);
1033  hikey = (IndexTuple) PageGetItem(state->origpage, itemid);
1034  perfectpenalty = _bt_keep_natts_fast(state->rel, hikey,
1035  state->newitem);
1036  if (perfectpenalty <= indnkeyatts)
1037  *strategy = SPLIT_SINGLE_VALUE;
1038  else
1039  {
1040  /*
1041  * Have caller finish split using default strategy, since page
1042  * does not appear to be the rightmost page for duplicates of the
1043  * value the page is filled with
1044  */
1045  }
1046  }
1047 
1048  return perfectpenalty;
1049 }
1050 
1051 /*
1052  * Subroutine to locate leftmost and rightmost splits for current/default
1053  * split interval. Note that it will be the same split iff there is only one
1054  * split in interval.
1055  */
1056 static void
1058  SplitPoint **rightinterval)
1059 {
1060  int highsplit = Min(state->interval, state->nsplits);
1061  SplitPoint *deltaoptimal;
1062 
1063  deltaoptimal = state->splits;
1064  *leftinterval = NULL;
1065  *rightinterval = NULL;
1066 
1067  /*
1068  * Delta is an absolute distance to optimal split point, so both the
1069  * leftmost and rightmost split point will usually be at the end of the
1070  * array
1071  */
1072  for (int i = highsplit - 1; i >= 0; i--)
1073  {
1074  SplitPoint *distant = state->splits + i;
1075 
1076  if (distant->firstrightoff < deltaoptimal->firstrightoff)
1077  {
1078  if (*leftinterval == NULL)
1079  *leftinterval = distant;
1080  }
1081  else if (distant->firstrightoff > deltaoptimal->firstrightoff)
1082  {
1083  if (*rightinterval == NULL)
1084  *rightinterval = distant;
1085  }
1086  else if (!distant->newitemonleft && deltaoptimal->newitemonleft)
1087  {
1088  /*
1089  * "incoming tuple will become firstright" (distant) is to the
1090  * left of "incoming tuple will become lastleft" (delta-optimal)
1091  */
1092  Assert(distant->firstrightoff == state->newitemoff);
1093  if (*leftinterval == NULL)
1094  *leftinterval = distant;
1095  }
1096  else if (distant->newitemonleft && !deltaoptimal->newitemonleft)
1097  {
1098  /*
1099  * "incoming tuple will become lastleft" (distant) is to the right
1100  * of "incoming tuple will become firstright" (delta-optimal)
1101  */
1102  Assert(distant->firstrightoff == state->newitemoff);
1103  if (*rightinterval == NULL)
1104  *rightinterval = distant;
1105  }
1106  else
1107  {
1108  /* There was only one or two splits in initial split interval */
1109  Assert(distant == deltaoptimal);
1110  if (*leftinterval == NULL)
1111  *leftinterval = distant;
1112  if (*rightinterval == NULL)
1113  *rightinterval = distant;
1114  }
1115 
1116  if (*leftinterval && *rightinterval)
1117  return;
1118  }
1119 
1120  Assert(false);
1121 }
1122 
1123 /*
1124  * Subroutine to find penalty for caller's candidate split point.
1125  *
1126  * On leaf pages, penalty is the attribute number that distinguishes each side
1127  * of a split. It's the last attribute that needs to be included in new high
1128  * key for left page. It can be greater than the number of key attributes in
1129  * cases where a heap TID will need to be appended during truncation.
1130  *
1131  * On internal pages, penalty is simply the size of the firstright tuple for
1132  * the split (including line pointer overhead). This tuple will become the
1133  * new high key for the left page.
1134  */
1135 static inline int
1137 {
1138  IndexTuple lastleft;
1139  IndexTuple firstright;
1140 
1141  if (!state->is_leaf)
1142  {
1143  ItemId itemid;
1144 
1145  if (!split->newitemonleft &&
1146  split->firstrightoff == state->newitemoff)
1147  return state->newitemsz;
1148 
1149  itemid = PageGetItemId(state->origpage, split->firstrightoff);
1150 
1151  return MAXALIGN(ItemIdGetLength(itemid)) + sizeof(ItemIdData);
1152  }
1153 
1154  lastleft = _bt_split_lastleft(state, split);
1155  firstright = _bt_split_firstright(state, split);
1156 
1157  return _bt_keep_natts_fast(state->rel, lastleft, firstright);
1158 }
1159 
1160 /*
1161  * Subroutine to get a lastleft IndexTuple for a split point
1162  */
1163 static inline IndexTuple
1165 {
1166  ItemId itemid;
1167 
1168  if (split->newitemonleft && split->firstrightoff == state->newitemoff)
1169  return state->newitem;
1170 
1171  itemid = PageGetItemId(state->origpage,
1173  return (IndexTuple) PageGetItem(state->origpage, itemid);
1174 }
1175 
1176 /*
1177  * Subroutine to get a firstright IndexTuple for a split point
1178  */
1179 static inline IndexTuple
1181 {
1182  ItemId itemid;
1183 
1184  if (!split->newitemonleft && split->firstrightoff == state->newitemoff)
1185  return state->newitem;
1186 
1187  itemid = PageGetItemId(state->origpage, split->firstrightoff);
1188  return (IndexTuple) PageGetItem(state->origpage, itemid);
1189 }
uint32 BlockNumber
Definition: block.h:31
Size PageGetExactFreeSpace(Page page)
Definition: bufpage.c:958
Pointer Page
Definition: bufpage.h:78
#define PageGetMaxOffsetNumber(page)
Definition: bufpage.h:356
#define PageGetItemId(page, offsetNumber)
Definition: bufpage.h:234
#define PageGetItem(page, itemId)
Definition: bufpage.h:339
#define SizeOfPageHeaderData
Definition: bufpage.h:215
#define PageGetPageSize(page)
Definition: bufpage.h:267
#define Min(x, y)
Definition: c.h:986
signed short int16
Definition: c.h:428
#define MAXALIGN(LEN)
Definition: c.h:757
size_t Size
Definition: c.h:540
#define ERROR
Definition: elog.h:33
#define elog(elevel,...)
Definition: elog.h:218
#define final(a, b, c)
Definition: hashfn.c:116
int i
Definition: isn.c:73
#define ItemIdGetLength(itemId)
Definition: itemid.h:59
struct ItemIdData ItemIdData
#define ItemPointerGetBlockNumber(pointer)
Definition: itemptr.h:98
#define ItemPointerGetOffsetNumber(pointer)
Definition: itemptr.h:117
IndexTupleData * IndexTuple
Definition: itup.h:53
#define IndexTupleSize(itup)
Definition: itup.h:70
Assert(fmt[strlen(fmt) - 1] !='\n')
void pfree(void *pointer)
Definition: mcxt.c:1175
void * palloc(Size size)
Definition: mcxt.c:1068
#define P_ISLEAF(opaque)
Definition: nbtree.h:221
#define BTREE_SINGLEVAL_FILLFACTOR
Definition: nbtree.h:203
#define P_HIKEY
Definition: nbtree.h:369
#define BTPageGetOpaque(page)
Definition: nbtree.h:73
#define P_FIRSTDATAKEY(opaque)
Definition: nbtree.h:371
static uint32 BTreeTupleGetPostingOffset(IndexTuple posting)
Definition: nbtree.h:524
#define P_RIGHTMOST(opaque)
Definition: nbtree.h:220
static bool BTreeTupleIsPosting(IndexTuple itup)
Definition: nbtree.h:487
#define BTGetFillFactor(relation)
Definition: nbtree.h:1095
#define P_FIRSTKEY
Definition: nbtree.h:370
#define BTREE_NONLEAF_FILLFACTOR
Definition: nbtree.h:202
OffsetNumber _bt_findsplitloc(Relation rel, Page origpage, OffsetNumber newitemoff, Size newitemsz, IndexTuple newitem, bool *newitemonleft)
Definition: nbtsplitloc.c:129
#define LEAF_SPLIT_DISTANCE
Definition: nbtsplitloc.c:854
static int _bt_split_penalty(FindSplitData *state, SplitPoint *split)
Definition: nbtsplitloc.c:1136
#define INTERNAL_SPLIT_DISTANCE
Definition: nbtsplitloc.c:855
static void _bt_deltasortsplits(FindSplitData *state, double fillfactormult, bool usemult)
Definition: nbtsplitloc.c:566
static int _bt_strategy(FindSplitData *state, SplitPoint *leftpage, SplitPoint *rightpage, FindSplitStrat *strategy)
Definition: nbtsplitloc.c:939
static bool _bt_afternewitemoff(FindSplitData *state, OffsetNumber maxoff, int leaffillfactor, bool *usemult)
Definition: nbtsplitloc.c:635
static int _bt_splitcmp(const void *arg1, const void *arg2)
Definition: nbtsplitloc.c:594
static IndexTuple _bt_split_lastleft(FindSplitData *state, SplitPoint *split)
Definition: nbtsplitloc.c:1164
static void _bt_recsplitloc(FindSplitData *state, OffsetNumber firstrightoff, bool newitemonleft, int olddataitemstoleft, Size firstrightofforigpagetuplesz)
Definition: nbtsplitloc.c:449
FindSplitStrat
Definition: nbtsplitloc.c:21
@ SPLIT_DEFAULT
Definition: nbtsplitloc.c:23
@ SPLIT_MANY_DUPLICATES
Definition: nbtsplitloc.c:24
@ SPLIT_SINGLE_VALUE
Definition: nbtsplitloc.c:25
static OffsetNumber _bt_bestsplitloc(FindSplitData *state, int perfectpenalty, bool *newitemonleft, FindSplitStrat strategy)
Definition: nbtsplitloc.c:793
static int _bt_defaultinterval(FindSplitData *state)
Definition: nbtsplitloc.c:881
static void _bt_interval_edges(FindSplitData *state, SplitPoint **leftinterval, SplitPoint **rightinterval)
Definition: nbtsplitloc.c:1057
static IndexTuple _bt_split_firstright(FindSplitData *state, SplitPoint *split)
Definition: nbtsplitloc.c:1180
static bool _bt_adjacenthtid(ItemPointer lowhtid, ItemPointer highhtid)
Definition: nbtsplitloc.c:754
int _bt_keep_natts_fast(Relation rel, IndexTuple lastleft, IndexTuple firstright)
Definition: nbtutils.c:2424
#define OffsetNumberNext(offsetNumber)
Definition: off.h:52
uint16 OffsetNumber
Definition: off.h:24
#define FirstOffsetNumber
Definition: off.h:27
#define OffsetNumberPrev(offsetNumber)
Definition: off.h:54
#define qsort(a, b, c, d)
Definition: port.h:495
#define RelationGetRelationName(relation)
Definition: rel.h:523
#define IndexRelationGetNumberOfKeyAttributes(relation)
Definition: rel.h:508
OffsetNumber newitemoff
Definition: nbtsplitloc.c:49
bool is_rightmost
Definition: nbtsplitloc.c:48
Size minfirstrightsz
Definition: nbtsplitloc.c:53
IndexTuple newitem
Definition: nbtsplitloc.c:45
SplitPoint * splits
Definition: nbtsplitloc.c:58
Relation rel
Definition: nbtsplitloc.c:43
int olddataitemstotal
Definition: nbtsplitloc.c:52
ItemPointerData t_tid
Definition: itup.h:37
bool newitemonleft
Definition: nbtsplitloc.c:37
OffsetNumber firstrightoff
Definition: nbtsplitloc.c:36
int16 leftfree
Definition: nbtsplitloc.c:32
int16 rightfree
Definition: nbtsplitloc.c:33
int16 curdelta
Definition: nbtsplitloc.c:31
Definition: regguts.h:318