On Wed, 11 May 2022 at 03:44, Bruce Momjian <bruce@momjian.us> wrote:
>
> I have completed the first draft of the PG 15 release notes and you can
> see the results here:
>
> https://momjian.us/pgsql_docs/release-15.html
Thanks for doing that tedious work.
I think the sort improvements done in v15 are worth a mention under
General Performance. The commits for this were 91e9e89dc, 40af10b57
and 697492434. I've been running a few benchmarks between v14 and v15
over the past few days and a fairly average case speedup is about 25%.
but there are cases where I've seen up to 400%. I think the increase
is to an extent that we maybe should have considered making tweaks in
cost_tuplesort(). I saw some plans that ran in about 60% of the time
by disabling Hash Agg and allowing Sort / Group Agg to do the work.
David