Horton

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

Peter Geoghegan <pg@bowt.ie>

View thread
From: Peter Geoghegan <pg@bowt.ie>
To: Todd Cook <cookt@blackduck.com>
Cc: Sajith Prabhakar Shetty <ssajith@blackduck.com>, Andrei Lepikhov <lepihov@gmail.com>, "pgsql-bugs@lists.postgresql.org" <pgsql-bugs@lists.postgresql.org>, Tom Lane <tgl@sss.pgh.pa.us>
Date: 2025-07-30T20:14:25Z
Lists: pgsql-bugs

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Convert strategies to and from compare types

  2. Enhance nbtree ScalarArrayOp execution.

  3. Improve planning of btree index scans using ScalarArrayOpExpr quals.

  4. Fix planning of btree index scans using ScalarArrayOpExpr quals.

On Wed, Jul 30, 2025 at 3:48 PM Todd Cook <cookt@blackduck.com> wrote:
> I work at the same company as Sajith, but on a different product.  The reproducer he
> provided is just a sample; it's not the only problem.  Load testing in my team shows
> that PG 17 is about 4x slower than PG 15 across the board.  It's bordering on unusable
> for production deployments.

I suggest that you rewrite affected queries to make them join against
a VALUES() with the same constants as those currently used in the
larger IN() list. If you're not sure whether the set of constants from
the application will be reliably unique, you can use DISTINCT to make
sure.

--
Peter Geoghegan