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Extend ExecBuildAggTrans() to support a NULL pointer check.

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Optionally push a step to check for a NULL pointer to the pergroup
state.

This will be important for disk-based hash aggregation in combination
with grouping sets. When memory limits are reached, a given tuple may
find its per-group state for some grouping sets but not others. For
the former, it advances the per-group state as normal; for the latter,
it skips evaluation and the calling code will have to spill the tuple
and reprocess it in a later batch.

Add the NULL check as a separate expression step because in some
common cases it's not needed.

Discussion: https://postgr.es/m/20200221202212.ssb2qpmdgrnx52sj%40alap3.anarazel.de
This commit is contained in:
Jeff Davis
2020-03-04 17:20:20 -08:00
parent 3ed2005ff5
commit c954d49046
6 changed files with 101 additions and 7 deletions
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src/include/executor/executor.h
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@ -255,7 +255,7 @@ extern ExprState *ExecInitQual(List *qual, PlanState *parent);
extern ExprState *ExecInitCheck(List *qual, PlanState *parent);
extern List *ExecInitExprList(List *nodes, PlanState *parent);
extern ExprState *ExecBuildAggTrans(AggState *aggstate, struct AggStatePerPhaseData *phase,
bool doSort, bool doHash);
bool doSort, bool doHash, bool nullcheck);
extern ExprState *ExecBuildGroupingEqual(TupleDesc ldesc, TupleDesc rdesc,
const TupleTableSlotOps *lops, const TupleTableSlotOps *rops,
int numCols,