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Treat JsonConstructorExpr as non-strict

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JsonConstructorExpr can produce non-NULL output with a NULL input, so
it should be treated as a non-strict construct.  Failing to do so can
lead to incorrect query behavior.

For example, in the reported case, when pulling up a subquery that is
under an outer join, if the subquery's target list contains a
JsonConstructorExpr that uses subquery variables and it is mistakenly
treated as strict, it will be pulled up without being wrapped in a
PlaceHolderVar.  As a result, the expression will be evaluated at the
wrong place and will not be forced to null when the outer join should
do so.

Back-patch to v16 where JsonConstructorExpr was introduced.

Bug: #19046
Reported-by: Runyuan He <runyuan@berkeley.edu>
Author: Tender Wang <tndrwang@gmail.com>
Co-authored-by: Richard Guo <guofenglinux@gmail.com>
Discussion: https://postgr.es/m/19046-765b6602b0a8cfdf@postgresql.org
Backpatch-through: 16
This commit is contained in:
Richard Guo
2025-09-16 18:42:20 +09:00
parent cfa6cd2927
commit b63a822452
3 changed files with 47 additions and 0 deletions
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2
src/backend/optimizer/util/clauses.c
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@@ -1115,6 +1115,8 @@ contain_nonstrict_functions_walker(Node *node, void *context)
return true;
if (IsA(node, BooleanTest))
return true;
if (IsA(node, JsonConstructorExpr))
return true;
/* Check other function-containing nodes */
if (check_functions_in_node(node, contain_nonstrict_functions_checker,