Re: Postgres: Queries are too slow after upgrading to PG17 from PG15

On Wed, Aug 20, 2025 at 7:48 PM Peter Geoghegan <pg@bowt.ie> wrote:
>
> On Tue, Aug 12, 2025 at 12:46 AM Sajith Prabhakar Shetty
> <ssajith@blackduck.com> wrote:
> > I can confirm with full certainty that both VACUUM and ANALYZE were executed on all three instances whose results I
shared.
>
> The results that you shared showed "Heap Fetches: 598,916" -- one heap
> fetch per index search (for the problematic index scan).
>
> Perhaps VACUUM ran without being truly effective, due to the removable
> cutoff/horizon being held back by a long running query. Though that
> generally won't happen on a quiescent system -- so it really does look
> like VACUUM hasn't been run.

Try running VACUUM FREEZE.   Do you have a way to frame up a dataset
for testing?

merlin