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In the executor, use an array of pointers to access the rangetable.

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Instead of doing a lot of list_nth() accesses to es_range_table,
create a flattened pointer array during executor startup and index
into that to get at individual RangeTblEntrys.

This eliminates one source of O(N^2) behavior with lots of partitions.
(I'm not exactly convinced that it's the most important source, but
it's an easy one to fix.)

Amit Langote and David Rowley

Discussion: https://postgr.es/m/468c85d9-540e-66a2-1dde-fec2b741e688@lab.ntt.co.jp
This commit is contained in:
Tom Lane
2018-10-04 15:48:17 -04:00
parent 9ddef36278
commit d73f4c74dd
11 changed files with 87 additions and 52 deletions
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9
src/include/executor/executor.h
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@ -514,6 +514,15 @@ extern bool ExecRelationIsTargetRelation(EState *estate, Index scanrelid);
extern Relation ExecOpenScanRelation(EState *estate, Index scanrelid, int eflags);
extern void ExecInitRangeTable(EState *estate, List *rangeTable);
static inline RangeTblEntry *
exec_rt_fetch(Index rti, EState *estate)
{
Assert(rti > 0 && rti <= estate->es_range_table_size);
return estate->es_range_table_array[rti - 1];
}
extern Relation ExecGetRangeTableRelation(EState *estate, Index rti);
extern int executor_errposition(EState *estate, int location);