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Reimplement planner's handling of MIN/MAX aggregate optimization (again).

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Instead of playing cute games with pathkeys, just build a direct
representation of the intended sub-select, and feed it through
query_planner to get a Path for the index access.  This is a bit slower
than 9.1's previous method, since we'll duplicate most of the overhead of
query_planner; but since the whole optimization only applies to rather
simple single-table queries, that probably won't be much of a problem in
practice.  The advantage is that we get to do the right thing when there's
a partial index that needs the implicit IS NOT NULL clause to be usable.
Also, although this makes planagg.c be a bit more closely tied to the
ordering of operations in grouping_planner, we can get rid of some coupling
to lower-level parts of the planner.  Per complaint from Marti Raudsepp.
This commit is contained in:
Tom Lane
2011-03-22 00:34:31 -04:00
parent 6d8096e2f3
commit 8df08c8489
12 changed files with 267 additions and 549 deletions
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14
src/backend/nodes/equalfuncs.c
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@@ -886,17 +886,6 @@ _equalPlaceHolderInfo(PlaceHolderInfo *a, PlaceHolderInfo *b)
return true;
}
static bool
_equalMinMaxAggInfo(MinMaxAggInfo *a, MinMaxAggInfo *b)
{
COMPARE_SCALAR_FIELD(aggfnoid);
COMPARE_SCALAR_FIELD(aggsortop);
COMPARE_NODE_FIELD(target);
COMPARE_NODE_FIELD(pathkeys);
return true;
}
/*
* Stuff from parsenodes.h
@@ -2690,9 +2679,6 @@ equal(void *a, void *b)
case T_PlaceHolderInfo:
retval = _equalPlaceHolderInfo(a, b);
break;
case T_MinMaxAggInfo:
retval = _equalMinMaxAggInfo(a, b);
break;
case T_List:
case T_IntList: