Re: suboverflowed subtransactions concurrency performance optimize - Mailing list pgsql-hackers

From Simon Riggs
Subject Re: suboverflowed subtransactions concurrency performance optimize
Date
Msg-id CANbhV-G8Co=yq4v4BkW7MJDqVt68K_8A48nAZ_+8UQS7LrwLEQ@mail.gmail.com
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In response to Re: suboverflowed subtransactions concurrency performance optimize  (Simon Riggs <simon.riggs@enterprisedb.com>)
Responses Re: suboverflowed subtransactions concurrency performance optimize
Re: suboverflowed subtransactions concurrency performance optimize
List pgsql-hackers
On Tue, 30 Nov 2021 at 12:19, Simon Riggs <simon.riggs@enterprisedb.com> wrote:
>
> On Mon, 30 Aug 2021 at 11:25, Andrey Borodin <x4mmm@yandex-team.ru> wrote:
> >
> > Hi Pengcheng!
> >
> > You are solving important problem, thank you!
> >
> > > 30 авг. 2021 г., в 13:43, Pengchengliu <pengchengliu@tju.edu.cn> написал(а):
> > >
> > > To resolve this performance problem, we think about a solution which cache
> > > SubtransSLRU to local cache.
> > > First we can query parent transaction id from SubtransSLRU, and copy the
> > > SLRU page to local cache page.
> > > After that if we need query parent transaction id again, we can query it
> > > from local cache directly.
> >
> > A copy of SLRU in each backend's cache can consume a lot of memory.
>
> Yes, copying the whole SLRU into local cache seems overkill.
>
> > Why create a copy if we can optimise shared representation of SLRU?
>
> transam.c uses a single item cache to prevent thrashing from repeated
> lookups, which reduces problems with shared access to SLRUs.
> multitrans.c also has similar.
>
> I notice that subtrans. doesn't have this, but could easily do so.
> Patch attached, which seems separate to other attempts at tuning.

Re-attached, so that the CFapp isn't confused between the multiple
patches on this thread.

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

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