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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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5
src/backend/commands/copy.c
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@ -2484,9 +2484,8 @@ CopyFrom(CopyState cstate)
estate->es_result_relations = resultRelInfo;
estate->es_num_result_relations = 1;
estate->es_result_relation_info = resultRelInfo;
estate->es_range_table = cstate->range_table;
estate->es_relations = (Relation *) palloc0(list_length(cstate->range_table) *
sizeof(Relation));
ExecInitRangeTable(estate, cstate->range_table);
/* Set up a tuple slot too */
myslot = ExecInitExtraTupleSlot(estate, tupDesc);