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Fix "wrong varnullingrels" for subquery nestloop parameters.

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If we apply outer join identity 3 when relation C is a subquery
having lateral references to relation B, then the lateral references
within C continue to bear the original syntactically-correct
varnullingrels marks, but that won't match what is available from
the outer side of the nestloop.  Compensate for that in
process_subquery_nestloop_params().  This is a slightly hacky fix,
but we certainly don't want to re-plan C in toto for each possible
outer join order, so there's not a lot of better alternatives.

Richard Guo and Tom Lane, per report from Markus Winand

Discussion: https://postgr.es/m/DFBB2D25-DE97-49CA-A60E-07C881EA59A7@winand.at
This commit is contained in:
Tom Lane
2023-06-12 10:01:26 -04:00
parent 548d726030
commit bfd332b3fd
4 changed files with 59 additions and 10 deletions
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8
src/backend/optimizer/plan/setrefs.c
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@@ -2289,9 +2289,11 @@ set_join_references(PlannerInfo *root, Join *join, int rtoffset)
* the outer-join level at which they are used, Vars seen in the
* NestLoopParam expression may have nullingrels that are just a
* subset of those in the Vars actually available from the outer
* side. Not checking this exactly is a bit grotty, but the work
* needed to make things match up perfectly seems well out of
* proportion to the value.
* side. Another case that can cause that to happen is explained
* in the comments for process_subquery_nestloop_params. Not
* checking this exactly is a bit grotty, but the work needed to
* make things match up perfectly seems well out of proportion to
* the value.
*/
nlp->paramval = (Var *) fix_upper_expr(root,
(Node *) nlp->paramval,