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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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2
src/backend/executor/nodeLockRows.c
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@ -400,7 +400,7 @@ ExecInitLockRows(LockRows *node, EState *estate, int eflags)
/*
* Create workspace in which we can remember per-RTE locked tuples
*/
lrstate->lr_ntables = list_length(estate->es_range_table);
lrstate->lr_ntables = estate->es_range_table_size;
lrstate->lr_curtuples = (HeapTuple *)
palloc0(lrstate->lr_ntables * sizeof(HeapTuple));