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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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19
src/backend/nodes/copyfuncs.c
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@ -1930,22 +1930,6 @@ _copyPlaceHolderInfo(PlaceHolderInfo *from)
return newnode;
}
/*
* _copyMinMaxAggInfo
*/
static MinMaxAggInfo *
_copyMinMaxAggInfo(MinMaxAggInfo *from)
{
MinMaxAggInfo *newnode = makeNode(MinMaxAggInfo);
COPY_SCALAR_FIELD(aggfnoid);
COPY_SCALAR_FIELD(aggsortop);
COPY_NODE_FIELD(target);
COPY_NODE_FIELD(pathkeys);
return newnode;
}
/* ****************************************************************
* parsenodes.h copy functions
* ****************************************************************
@ -4129,9 +4113,6 @@ copyObject(void *from)
case T_PlaceHolderInfo:
retval = _copyPlaceHolderInfo(from);
break;
case T_MinMaxAggInfo:
retval = _copyMinMaxAggInfo(from);
break;
/*
* VALUE NODES