On Mon, 2026-02-23 at 10:37 +0100, Attila Soki wrote: > When upgrading from PostgreSQL 14.4, I noticed that one of my somewhat complex > analytical queries sometimes gets an inefficient plan under PostgreSQL 16, > 17, and 18. > Under 14.4, the query runs with a stable plan and completes in 19 to 22 > seconds. > In newer versions, the plan seems to be unstable, sometimes the query > completes > in 17 to 20 seconds, sometimes it runs for 5 to 18 minutes with the > inefficient plan. > This also happens even if the data is not significantly changed.
This is very likely owing to a bad estimate. Could you turn on "track_io_timing" and send us the EXPLAIN (ANALYZE, BUFFERS) output for both the good and the bad plan? Yours, Laurenz Albe
