Re: track_planning causing performance regression

On 2020/07/03 16:02, Pavel Stehule wrote:
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> pá 3. 7. 2020 v 8:57 odesílatel Fujii Masao <masao(dot)fujii(at)oss(dot)nttdata(dot)com <mailto:masao(dot)fujii(at)oss(dot)nttdata(dot)com>> napsal:
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> 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> <mailto:masao(dot)fujii(at)oss(dot)nttdata(dot)com <mailto:masao(dot)fujii(at)oss(dot)nttdata(dot)com>>> napsal:
> >
> >
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> >     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> <mailto: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.
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> >
> > Maybe there can be documented so enabling this option can have a negative impact on performance.
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> Yes. What about adding either of the followings into the doc?
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>      Enabling this parameter may incur a noticeable performance penalty.
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> or
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>      Enabling this parameter may incur a noticeable performance penalty,
>      especially when a fewer kinds of queries are executed on many
>      concurrent connections.
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> This second variant looks perfect for this case.

Ok, so patch attached.

Regards,

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