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Use parameterized paths to generate inner indexscans more flexibly.

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This patch fixes the planner so that it can generate nestloop-with-
inner-indexscan plans even with one or more levels of joining between
the indexscan and the nestloop join that is supplying the parameter.
The executor was fixed to handle such cases some time ago, but the
planner was not ready.  This should improve our plans in many situations
where join ordering restrictions formerly forced complete table scans.

There is probably a fair amount of tuning work yet to be done, because
of various heuristics that have been added to limit the number of
parameterized paths considered.  However, we are not going to find out
what needs to be adjusted until the code gets some real-world use, so
it's time to get it in there where it can be tested easily.

Note API change for index AM amcostestimate functions.  I'm not aware of
any non-core index AMs, but if there are any, they will need minor
adjustments.
This commit is contained in:
Tom Lane
2012-01-27 19:26:38 -05:00
parent b376ec6fa5
commit e2fa76d80b
26 changed files with 3884 additions and 2292 deletions
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77
src/backend/nodes/bitmapset.c
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@ -335,6 +335,83 @@ bms_is_subset(const Bitmapset *a, const Bitmapset *b)
return true;
}
/*
* bms_subset_compare - compare A and B for equality/subset relationships
*
* This is more efficient than testing bms_is_subset in both directions.
*/
BMS_Comparison
bms_subset_compare(const Bitmapset *a, const Bitmapset *b)
{
BMS_Comparison result;
int shortlen;
int longlen;
int i;
/* Handle cases where either input is NULL */
if (a == NULL)
{
if (b == NULL)
return BMS_EQUAL;
return bms_is_empty(b) ? BMS_EQUAL : BMS_SUBSET1;
}
if (b == NULL)
return bms_is_empty(a) ? BMS_EQUAL : BMS_SUBSET2;
/* Check common words */
result = BMS_EQUAL; /* status so far */
shortlen = Min(a->nwords, b->nwords);
for (i = 0; i < shortlen; i++)
{
bitmapword aword = a->words[i];
bitmapword bword = b->words[i];
if ((aword & ~bword) != 0)
{
/* a is not a subset of b */
if (result == BMS_SUBSET1)
return BMS_DIFFERENT;
result = BMS_SUBSET2;
}
if ((bword & ~aword) != 0)
{
/* b is not a subset of a */
if (result == BMS_SUBSET2)
return BMS_DIFFERENT;
result = BMS_SUBSET1;
}
}
/* Check extra words */
if (a->nwords > b->nwords)
{
longlen = a->nwords;
for (; i < longlen; i++)
{
if (a->words[i] != 0)
{
/* a is not a subset of b */
if (result == BMS_SUBSET1)
return BMS_DIFFERENT;
result = BMS_SUBSET2;
}
}
}
else if (a->nwords < b->nwords)
{
longlen = b->nwords;
for (; i < longlen; i++)
{
if (b->words[i] != 0)
{
/* b is not a subset of a */
if (result == BMS_SUBSET2)
return BMS_DIFFERENT;
result = BMS_SUBSET1;
}
}
}
return result;
}
/*
* bms_is_member - is X a member of A?
*/