On Wed, 27 Mar 2024 at 06:00, Alexander Lakhin <exclusion@gmail.com> wrote:
> SELECT count(*) FROM (
> WITH q1(x) AS (SELECT 1)
> SELECT FROM q1 UNION SELECT FROM q1
> ) qu;
>
> TRAP: failed Assert("lg != NULL"), File: "planner.c", Line: 7941, PID: 1133017
Thanks for finding that.
There's something weird going on with the UNION child subquery's
setOperations field. As far as I understand, and from reading the
existing comments, this should only be set for the top-level union.
Because this field is set, it plans the CTE thinking it's a UNION
child and breaks when it can't find a SortGroupClause for the CTE's
target list item.
I'll keep digging. As far as I see the setOperations field is only set
in transformSetOperationStmt(). I'm guessing we must be doing a
copyObject() somewhere and accidentally picking up the parent's
setOperations.
David
