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Fix oversight in outer join removal.

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A placeholder that references the outer join's relid in ph_eval_at
is logically "above" the join, and therefore we can't remove its
PlaceHolderInfo: it might still be used somewhere in the query.

This was not an issue pre-v16 because we failed to remove the join
at all in such cases.  The new outer-join-aware-Var infrastructure
permits deducing that it's okay to remove the join, but then we
have to clean up correctly afterwards.

Report and fix by Richard Guo

Discussion: https://postgr.es/m/CAMbWs4_tuVn9EwwMcggGiZJWWstdXX_ci8FeEU17vs+4nLgw3w@mail.gmail.com
This commit is contained in:
Tom Lane
2023-06-08 17:10:04 -04:00
parent fbf80421ea
commit 9a2dbc614e
3 changed files with 93 additions and 1 deletions
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3
src/backend/optimizer/plan/analyzejoins.c
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@@ -425,7 +425,8 @@ remove_rel_from_query(PlannerInfo *root, int relid, SpecialJoinInfo *sjinfo)
Assert(!bms_is_member(relid, phinfo->ph_lateral));
if (bms_is_subset(phinfo->ph_needed, joinrelids) &&
bms_is_member(relid, phinfo->ph_eval_at))
bms_is_member(relid, phinfo->ph_eval_at) &&
!bms_is_member(ojrelid, phinfo->ph_eval_at))
{
root->placeholder_list = foreach_delete_current(root->placeholder_list,
l);