avamingli commented on PR #1284: URL: https://github.com/apache/cloudberry/pull/1284#issuecomment-3153580599
Previously, we attempted to disable window functions inside CASE WHEN expressions due to concerns about unstable parallel results. However, this was a misunderstanding. All expressions from the subquery are Var columns, not the original expressions. This issue was uncovered when we fixed the subquery row count estimation, causing the cost to change in the upper plan. Fixed at commit: [Correct parallel window function in CASE WHEN.](https://github.com/apache/cloudberry/pull/1284/commits/0791ff62b08743682e81da41e7458e7b39b92d7a) ```sql EXPLAIN(COSTS OFF) SELECT empno, depname, salary, bonus, depadj, MIN(bonus) OVER (ORDER BY empno), MAX(depadj) OVER () FROM( SELECT *, CASE WHEN enroll_date < '2008-01-01' THEN 2008 - extract(YEAR FROM enroll_date) END * 500 AS bonus, CASE WHEN AVG(salary) OVER (PARTITION BY depname) < salary THEN 200 END AS depadj FROM empsalary )s; QUERY PLAN -------------------------------------------------------------------------- WindowAgg -> WindowAgg Order By: s.empno -> Gather Motion 6:1 (slice1; segments: 6) Merge Key: s.empno -> Sort Sort Key: s.empno -> Subquery Scan on s -> WindowAgg Partition By: empsalary.depname -> Sort Sort Key: empsalary.depname -> Redistribute Motion 6:6 (slice2; segments: 6) Hash Key: empsalary.depname Hash Module: 3 -> Parallel Seq Scan on empsalary Optimizer: Postgres query optimizer (17 rows) ``` -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
