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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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12
contrib/postgres_fdw/postgres_fdw.c
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@ -1345,7 +1345,7 @@ postgresBeginForeignScan(ForeignScanState *node, int eflags)
rtindex = fsplan->scan.scanrelid;
else
rtindex = bms_next_member(fsplan->fs_relids, -1);
rte = rt_fetch(rtindex, estate->es_range_table);
rte = exec_rt_fetch(rtindex, estate);
userid = rte->checkAsUser ? rte->checkAsUser : GetUserId();
/* Get info about foreign table. */
@ -1731,8 +1731,8 @@ postgresBeginForeignModify(ModifyTableState *mtstate,
FdwModifyPrivateRetrievedAttrs);
/* Find RTE. */
rte = rt_fetch(resultRelInfo->ri_RangeTableIndex,
mtstate->ps.state->es_range_table);
rte = exec_rt_fetch(resultRelInfo->ri_RangeTableIndex,
mtstate->ps.state);
/* Construct an execution state. */
fmstate = create_foreign_modify(mtstate->ps.state,
@ -2036,7 +2036,7 @@ postgresBeginForeignInsert(ModifyTableState *mtstate,
* correspond to this partition if it is one of the UPDATE subplan target
* rels; in that case, we can just use the existing RTE as-is.
*/
rte = list_nth(estate->es_range_table, resultRelation - 1);
rte = exec_rt_fetch(resultRelation, estate);
if (rte->relid != RelationGetRelid(rel))
{
rte = copyObject(rte);
@ -2396,7 +2396,7 @@ postgresBeginDirectModify(ForeignScanState *node, int eflags)
* ExecCheckRTEPerms() does.
*/
rtindex = estate->es_result_relation_info->ri_RangeTableIndex;
rte = rt_fetch(rtindex, estate->es_range_table);
rte = exec_rt_fetch(rtindex, estate);
userid = rte->checkAsUser ? rte->checkAsUser : GetUserId();
/* Get info about foreign table. */
@ -5752,7 +5752,7 @@ conversion_error_callback(void *arg)
RangeTblEntry *rte;
Var *var = (Var *) tle->expr;
rte = rt_fetch(var->varno, estate->es_range_table);
rte = exec_rt_fetch(var->varno, estate);
if (var->varattno == 0)
is_wholerow = true;