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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
2009-04-07 17:49:40 +00:00
parent 1b40567c55
commit ca1316dfa3
2 changed files with 164 additions and 48 deletions
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127
contrib/rtree_gist/rtree_gist.c
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@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/contrib/rtree_gist/Attic/rtree_gist.c,v 1.7 2003/07/27 17:10:06 tgl Exp $
* $Header: /cvsroot/pgsql/contrib/rtree_gist/Attic/rtree_gist.c,v 1.7.4.1 2009/04/07 17:49:40 teodor Exp $
*
*-------------------------------------------------------------------------
*/
@ -178,6 +178,72 @@ compare_KB(const void *a, const void *b)
return (sa > sb) ? 1 : -1;
}
static void
adjustBox(BOX *b, BOX *addon)
{
if (b->high.x < addon->high.x)
b->high.x = addon->high.x;
if (b->low.x > addon->low.x)
b->low.x = addon->low.x;
if (b->high.y < addon->high.y)
b->high.y = addon->high.y;
if (b->low.y > addon->low.y)
b->low.y = addon->low.y;
}
/*
* Trivial split: half of entries will be placed on one page
* and another half - to another
*/
static void
fallbackSplit(bytea *entryvec, GIST_SPLITVEC *v)
{
OffsetNumber i,
maxoff;
BOX *unionL = NULL,
*unionR = NULL;
int nbytes;
maxoff = ((VARSIZE(entryvec) - VARHDRSZ) / sizeof(GISTENTRY)) - 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(((GISTENTRY *) VARDATA(entryvec))[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++;
}
}
}
/*
** The GiST PickSplit method
** New linear algorithm, see 'New Linear Node Splitting Algorithm for R-tree',
@ -226,54 +292,25 @@ gbox_picksplit(PG_FUNCTION_ARGS)
))
allisequal = false;
if (pageunion.high.x < cur->high.x)
pageunion.high.x = cur->high.x;
if (pageunion.low.x > cur->low.x)
pageunion.low.x = cur->low.x;
if (pageunion.high.y < cur->high.y)
pageunion.high.y = cur->high.y;
if (pageunion.low.y > cur->low.y)
pageunion.low.y = cur->low.y;
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(((GISTENTRY *) VARDATA(entryvec))[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++;
}
}
v->spl_ldatum = BoxPGetDatum(unionL);
v->spl_rdatum = BoxPGetDatum(unionR);
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));
@ -343,6 +380,12 @@ gbox_picksplit(PG_FUNCTION_ARGS)
ADDLIST(listT, unionT, posT, arr[i - 1].pos);
}
pfree(arr);
if ((posR == 0 || posL == 0) && (posT == 0 || posB == 0))
{
fallbackSplit(entryvec, v);
PG_RETURN_POINTER(v);
}
}
/* which split more optimal? */