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Fix 'all at one page bug' in picksplit method of R-tree emulation. Add defense

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from buggy user-defined picksplit to GiST.
This commit is contained in:
Teodor Sigaev
2009-04-06 14:27:27 +00:00
parent 1eef90d0a2
commit 09368d23db
2 changed files with 175 additions and 54 deletions
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123
src/backend/access/gist/gistproc.c
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@ -10,7 +10,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/access/gist/gistproc.c,v 1.15 2009/01/01 17:23:35 momjian Exp $
* $PostgreSQL: pgsql/src/backend/access/gist/gistproc.c,v 1.16 2009/04/06 14:27:27 teodor Exp $
*
*-------------------------------------------------------------------------
*/
@ -272,6 +272,69 @@ chooseLR(GIST_SPLITVEC *v,
v->spl_ldatum_exists = v->spl_rdatum_exists = false;
}
/*
* Trivial split: half of entries will be placed on one page
* and another half - to another
*/
static void
fallbackSplit(GistEntryVector *entryvec, GIST_SPLITVEC *v)
{
OffsetNumber i,
maxoff;
BOX *unionL = NULL,
*unionR = NULL;
int nbytes;
maxoff = entryvec->n - 1;
nbytes = (maxoff + 2) * sizeof(OffsetNumber);
v->spl_left = (OffsetNumber *) palloc(nbytes);
v->spl_right = (OffsetNumber *) palloc(nbytes);
v->spl_nleft = v->spl_nright = 0;
for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
{
BOX * cur = DatumGetBoxP(entryvec->vector[i].key);
if (i <= (maxoff - FirstOffsetNumber + 1) / 2)
{
v->spl_left[v->spl_nleft] = i;
if (unionL == NULL)
{
unionL = (BOX *) palloc(sizeof(BOX));
*unionL = *cur;
}
else
adjustBox(unionL, cur);
v->spl_nleft++;
}
else
{
v->spl_right[v->spl_nright] = i;
if (unionR == NULL)
{
unionR = (BOX *) palloc(sizeof(BOX));
*unionR = *cur;
}
else
adjustBox(unionR, cur);
v->spl_nright++;
}
}
if (v->spl_ldatum_exists)
adjustBox(unionL, DatumGetBoxP(v->spl_ldatum));
v->spl_ldatum = BoxPGetDatum(unionL);
if (v->spl_rdatum_exists)
adjustBox(unionR, DatumGetBoxP(v->spl_rdatum));
v->spl_rdatum = BoxPGetDatum(unionR);
v->spl_ldatum_exists = v->spl_rdatum_exists = false;
}
/*
* The GiST PickSplit method
*
@ -324,52 +387,22 @@ gist_box_picksplit(PG_FUNCTION_ARGS)
adjustBox(&pageunion, cur);
}
if (allisequal)
{
/*
* All entries are the same
*/
fallbackSplit(entryvec, v);
PG_RETURN_POINTER(v);
}
nbytes = (maxoff + 2) * sizeof(OffsetNumber);
listL = (OffsetNumber *) palloc(nbytes);
listR = (OffsetNumber *) palloc(nbytes);
unionL = (BOX *) palloc(sizeof(BOX));
unionR = (BOX *) palloc(sizeof(BOX));
if (allisequal)
{
cur = DatumGetBoxP(entryvec->vector[OffsetNumberNext(FirstOffsetNumber)].key);
if (memcmp((void *) cur, (void *) &pageunion, sizeof(BOX)) == 0)
{
v->spl_left = listL;
v->spl_right = listR;
v->spl_nleft = v->spl_nright = 0;
memcpy((void *) unionL, (void *) &pageunion, sizeof(BOX));
memcpy((void *) unionR, (void *) &pageunion, sizeof(BOX));
for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
{
if (i <= (maxoff - FirstOffsetNumber + 1) / 2)
{
v->spl_left[v->spl_nleft] = i;
v->spl_nleft++;
}
else
{
v->spl_right[v->spl_nright] = i;
v->spl_nright++;
}
}
if (v->spl_ldatum_exists)
adjustBox(unionL, DatumGetBoxP(v->spl_ldatum));
v->spl_ldatum = BoxPGetDatum(unionL);
if (v->spl_rdatum_exists)
adjustBox(unionR, DatumGetBoxP(v->spl_rdatum));
v->spl_rdatum = BoxPGetDatum(unionR);
v->spl_ldatum_exists = v->spl_rdatum_exists = false;
PG_RETURN_POINTER(v);
}
}
listB = (OffsetNumber *) palloc(nbytes);
listT = (OffsetNumber *) palloc(nbytes);
unionL = (BOX *) palloc(sizeof(BOX));
unionR = (BOX *) palloc(sizeof(BOX));
unionB = (BOX *) palloc(sizeof(BOX));
unionT = (BOX *) palloc(sizeof(BOX));
@ -452,6 +485,12 @@ gist_box_picksplit(PG_FUNCTION_ARGS)
else
ADDLIST(listT, unionT, posT, i);
}
if (IS_BADRATIO(posR, posL) && IS_BADRATIO(posT, posB))
{
fallbackSplit(entryvec, v);
PG_RETURN_POINTER(v);
}
}
/* which split more optimal? */