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Calculate agglevelsup correctly when Aggref contains a CTE.

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If an aggregate function call contains a sub-select that has
an RTE referencing a CTE outside the aggregate, we must treat
that reference like a Var referencing the CTE's query level
for purposes of determining the aggregate's level.  Otherwise
we might reach the nonsensical conclusion that the aggregate
should be evaluated at some query level higher than the CTE,
ending in a planner error or a broken plan tree that causes
executor failures.

Bug: #19055
Reported-by: BugForge <dllggyx@outlook.com>
Author: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/19055-6970cfa8556a394d@postgresql.org
Backpatch-through: 13
This commit is contained in:
Tom Lane
2025-09-17 16:32:57 -04:00
parent 0951942bba
commit b0cc0a71e0
3 changed files with 75 additions and 1 deletions
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28
src/backend/parser/parse_agg.c
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@@ -791,6 +791,32 @@ check_agg_arguments_walker(Node *node,
parser_errposition(context->pstate,
((WindowFunc *) node)->location)));
}
if (IsA(node, RangeTblEntry))
{
/*
* CTE references act similarly to Vars of the CTE's level. Without
* this we might conclude that the Agg can be evaluated above the CTE,
* leading to trouble.
*/
RangeTblEntry *rte = (RangeTblEntry *) node;
if (rte->rtekind == RTE_CTE)
{
int ctelevelsup = rte->ctelevelsup;
/* convert levelsup to frame of reference of original query */
ctelevelsup -= context->sublevels_up;
/* ignore local CTEs of subqueries */
if (ctelevelsup >= 0)
{
if (context->min_varlevel < 0 ||
context->min_varlevel > ctelevelsup)
context->min_varlevel = ctelevelsup;
}
}
return false; /* allow range_table_walker to continue */
}
if (IsA(node, Query))
{
/* Recurse into subselects */
@@ -800,7 +826,7 @@ check_agg_arguments_walker(Node *node,
result = query_tree_walker((Query *) node,
check_agg_arguments_walker,
context,
0);
QTW_EXAMINE_RTES_BEFORE);
context->sublevels_up--;
return result;
}