Re: BUG #16223: Performance regression between 11.6 and 12.1 in an SQL query with a recursive CTE based on function

Christian Schwaderer <schwaderer(at)ivocotec(dot)de> writes:
> I only tested on those virtual environments mentioned (Virtual Box and
> Docker) as they resemble my real life scenarios. Environments were
> equivalent except for the PostgreSQL version. As you can see, I used
> Docker images from the official PostgreSQL docker repo (
> https://hub.docker.com/_/postgres ) and did nothing with them except
> running the query.

> Thanks for testing without virtualization! So, it seems we can narrow
> down the issue to virtual environments. Strange enough, if you ask me.

Or it could be the specific builds you used. Some of our packagers
tend to enable debug options on early releases of a given major version;
if that was the case for the v12 build you tested, it could account for
at least some of the difference. Comparing pg_config output from the
two installations (particularly the configure options) would be
informative.

Another thing that could be relevant is JIT, which is on by default
in v12 (if enabled in configuration), and which is still suffering
a lot of teething pains performance-wise. I'd check if that's
on and try disabling it if so.

regards, tom lane