Re: suboverflowed subtransactions concurrency performance optimize

On Wed, 1 Dec 2021 at 06:41, Andrey Borodin <x4mmm@yandex-team.ru> wrote:

> > On review, I think it is also possible that we update subtrans ONLY if
> > someone uses >PGPROC_MAX_CACHED_SUBXIDS.
> > This would make subtrans much smaller and avoid one-entry-per-page
> > which is a major source of cacheing.
> > This would means some light changes in GetSnapshotData().
> > Let me know if that seems interesting also?
>
> I'm afraid of unexpected performance degradation. When the system runs fine, you provision a VM of some vCPU\RAM, and then some backend uses a little more than 64 subtransactions and all the system is stuck. Or will it affect only backend using more than 64 subtransactions?

That is the objective: to isolate the effect to only those that
overflow. It seems possible.

-- 
Simon Riggs                http://www.EnterpriseDB.com/