Zhang Mingli
www.hashdata.xyz
On Jan 17, 2025 at 07:35 +0800, Tom Lane <tgl@sss.pgh.pa.us>, wrote:
PG Bug reporting form <noreply@postgresql.org> writes:
The following script:
CREATE TABLE t (id int, PRIMARY KEY (id)) PARTITION BY RANGE (id);
CREATE TABLE t0 PARTITION OF t FOR VALUES FROM (0) TO (1);
CREATE TABLE t1 PARTITION OF t FOR VALUES FROM (1) TO (2);
SELECT 1 FROM (SELECT EXISTS (SELECT 1 FROM t0 WHERE id = t00.id) AS b FROM
t0 t00) r, t
WHERE t.id > CASE WHEN jsonb_build_object(b) IS NULL THEN 1 ELSE 1 END;
fails with:
ERROR: XX000: unrecognized node type: 24
Thanks for the report! setrefs.c is supposed to remove
AlternativeSubPlan nodes from the plan, but it's failing to do so
here. Digging, the un-cleaned-up AlternativeSubPlan is inside the
exec_pruning_steps of an Append node's part_prune_info, and I see
that setrefs is totally unaware that those expressions might need
processing. I think it ought to be applying fix_scan_expr to them,
as per the attached. There are a bunch of tidying-up things that
fix_scan_expr does, so I suspect that there may be more bug symptoms
reachable from this oversight. Some of the missed processing may be
redundant --- for example it's likely that
record_plan_function_dependency is duplicative because functions used
here would also be used elsewhere in the query. But it's hard to
believe it all is.
Hi, I have tested the patch, and confirm that it works well. Additionally, I believe it might be worth creating a test case for it.
And I have a question that may not be directly related to the issue: why is there a Subplan 2, and it appears to be unused?
explain(costs off, verbose) SELECT 1 FROM (SELECT EXISTS (SELECT 1 FROM t0 WHERE id = t00.id) AS b FROM
t0 t00) r, t WHERE t.id > CASE WHEN jsonb_build_object(b) IS NULL THEN 1 ELSE 1 END;
QUERY PLAN
------------------------------------------------------------------------------------------------------------------
Nested Loop
Output: 1
-> Seq Scan on public.t0 t00
Output: t00.id
-> Append
-> Index Only Scan using t0_pkey on public.t0 t_1
Output: t_1.id
Index Cond: (t_1.id > CASE WHEN (jsonb_build_object(EXISTS(SubPlan 1)) IS NULL) THEN 1 ELSE 1 END)
SubPlan 2
-> Seq Scan on public.t0 t0_1
Output: t0_1.id
-> Index Only Scan using t1_pkey on public.t1 t_2
Output: t_2.id
Index Cond: (t_2.id > CASE WHEN (jsonb_build_object(EXISTS(SubPlan 1)) IS NULL) THEN 1 ELSE 1 END)
SubPlan 1
-> Index Only Scan using t0_pkey on public.t0
Index Cond: (t0.id = t00.id)
(17 rows)
