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Fix thinko in join removal.

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In commit 9df8f903e I (tgl) switched join_is_removable() from
using the min relid sets of the join under consideration to
using its full syntactic relid sets.  This was a mistake,
as it allowed join removal in cases where a reference to the
join output would survive in some syntactically-lower join
condition.  Revert to the former coding.

Richard Guo

Discussion: https://postgr.es/m/CAMbWs4-EU9uBGSP7G-iTwLBhRQ=rnZKvFDhD+n+xhajokyPCKg@mail.gmail.com
This commit is contained in:
Tom Lane
2023-05-19 15:24:07 -04:00
parent 70b42f2790
commit d0f952691f
3 changed files with 25 additions and 7 deletions
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11
src/backend/optimizer/plan/analyzejoins.c
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@@ -88,11 +88,8 @@ restart:
*/
innerrelid = bms_singleton_member(sjinfo->min_righthand);
/*
* Compute the relid set for the join we are considering. We can
* assume things are done in syntactic order.
*/
joinrelids = bms_union(sjinfo->syn_lefthand, sjinfo->syn_righthand);
/* Compute the relid set for the join we are considering */
joinrelids = bms_union(sjinfo->min_lefthand, sjinfo->min_righthand);
if (sjinfo->ojrelid != 0)
joinrelids = bms_add_member(joinrelids, sjinfo->ojrelid);
@@ -204,8 +201,8 @@ join_is_removable(PlannerInfo *root, SpecialJoinInfo *sjinfo)
if (!rel_supports_distinctness(root, innerrel))
return false;
/* Compute the syntactic relid set for the join we are considering */
inputrelids = bms_union(sjinfo->syn_lefthand, sjinfo->syn_righthand);
/* Compute the relid set for the join we are considering */
inputrelids = bms_union(sjinfo->min_lefthand, sjinfo->min_righthand);
Assert(sjinfo->ojrelid != 0);
joinrelids = bms_copy(inputrelids);
joinrelids = bms_add_member(joinrelids, sjinfo->ojrelid);