Re: track_planning causing performance regression

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.

Regards,

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