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Commit51ad5b9

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jit: Re-allow JIT compilation of execGrouping.c hashtable comparisons.
In the course of5567d12,356687b and317ffdf, I changedBuildTupleHashTable[Ext]'s call to ExecBuildGroupingEqual to not passin the parent node, but NULL. Which in turn prevents the tupleequality comparator from being JIT compiled. While that fixesbug #15486, it is not actually necessary after all of the above commits,as we don't re-build the comparator when using the newBuildTupleHashTableExt() interface (as the content of the hashtableare reset, but the TupleHashTable itself is not).Therefore re-allow jit compilation for callers that useBuildTupleHashTableExt with a separate context for "metadata" andcontent.As in the previous commit, there's ongoing work to make this easier totest to prevent such regressions in the future, but thatinfrastructure is not going to be backpatchable.The performance impact of not JIT compiling hashtable equalitycomparators can be substantial e.g. for aggregation queries thataggregate a lot of input rows to few output rows (when there are a lotof output groups, there will be fewer comparisons).Author: Andres FreundDiscussion:https://postgr.es/m/20190927072053.njf6prdl3vb7y7qb@alap3.anarazel.deBackpatch: 11, just as5567d12
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‎src/backend/executor/execGrouping.c

Lines changed: 12 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -164,6 +164,7 @@ BuildTupleHashTableExt(PlanState *parent,
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TupleHashTablehashtable;
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Sizeentrysize=sizeof(TupleHashEntryData)+additionalsize;
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MemoryContextoldcontext;
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boolallow_jit;
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Assert(nbuckets>0);
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@@ -206,11 +207,21 @@ BuildTupleHashTableExt(PlanState *parent,
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*/
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hashtable->tableslot=MakeSingleTupleTableSlot(CreateTupleDescCopy(inputDesc));
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/*
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* If the old reset interface is used (i.e. BuildTupleHashTable, rather
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* than BuildTupleHashTableExt), allowing JIT would lead to the generated
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* functions to a) live longer than the query b) be re-generated each time
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* the table is being reset. Therefore prevent JIT from being used in that
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* case, by not providing a parent node (which prevents accessing the
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* JitContext in the EState).
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*/
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allow_jit=metacxt!=tablecxt;
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/* build comparator for all columns */
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hashtable->tab_eq_func=ExecBuildGroupingEqual(inputDesc,inputDesc,
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numCols,
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keyColIdx,eqfuncoids,
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NULL);
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allow_jit ?parent :NULL);
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/*
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* While not pretty, it's ok to not shut down this context, but instead

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