On Fri, Jun 27, 2025 at 9:35 AM Zechman, Derek S <derek.s.zech...@snapon.com> wrote:
> > > We recently performed an upgrade from pg14 (14.18) to pg16 (16.9) and > performed the analyze-in-stages post upgrade. It has been noticed that > some plans changed to use hash joins instead of nested loops. Further > investigation found it was because the parent table of partitioned tables > did not have stats. After running an ANALYZE on the parent tables we got > similar plan an execution times as before. > > > > I have two questions > > 1 - Why does analyze-in-stages not analyze the parent tables? > > 2 – What happens if we do not run analyze-in-stages post upgrade and just > run an analyze? > It takes more time, and you don't have *any* statistics on a given table until the ANALYZE on that table completes. How long did "vacuumdb --analyze-only --jobs=$mumble your_db" take? -- Death to <Redacted>, and butter sauce. Don't boil me, I'm still alive. <Redacted> lobster!
