Re: track_planning causing performance regression

pá 3. 7. 2020 v 8:57 odesílatel Fujii Masao <masao(dot)fujii(at)oss(dot)nttdata(dot)com>
napsal:

>
>
> On 2020/07/03 13:05, Pavel Stehule wrote:
> > Hi
> >
> > pá 3. 7. 2020 v 4:39 odesílatel Fujii Masao <masao(dot)fujii(at)oss(dot)nttdata(dot)com
> <mailto:masao(dot)fujii(at)oss(dot)nttdata(dot)com>> napsal:
> >
> >
> >
> > On 2020/07/01 7:37, Peter Geoghegan wrote:
> > > On Tue, Jun 30, 2020 at 6:40 AM Fujii Masao <
> masao(dot)fujii(at)oss(dot)nttdata(dot)com <mailto:masao(dot)fujii(at)oss(dot)nttdata(dot)com>> wrote:
> > >> Ants and Andres suggested to replace the spinlock used in
> pgss_store() with
> > >> LWLock. I agreed with them and posted the POC patch doing that.
> But I think
> > >> the patch is an item for v14. The patch may address the reported
> performance
> > >> issue, but may cause other performance issues in other
> workloads. We would
> > >> need to measure how the patch affects the performance in various
> workloads.
> > >> It seems too late to do that at this stage of v13. Thought?
> > >
> > > I agree that it's too late for v13.
> >
> > Thanks for the comment!
> >
> > So I pushed the patch and changed default of track_planning to off.
> >
> >
> > Maybe there can be documented so enabling this option can have a
> negative impact on performance.
>
> Yes. What about adding either of the followings into the doc?
>
> Enabling this parameter may incur a noticeable performance penalty.
>
> or
>
> Enabling this parameter may incur a noticeable performance penalty,
> especially when a fewer kinds of queries are executed on many
> concurrent connections.
>

This second variant looks perfect for this case.

Thank you

Pavel

> Regards,
>
> --
> Fujii Masao
> Advanced Computing Technology Center
> Research and Development Headquarters
> NTT DATA CORPORATION
>