On 2020/07/03 16:02, Pavel Stehule wrote:
pá 3. 7. 2020 v 8:57 odesílatel Fujii Masao <[email protected]
<mailto:[email protected]>> napsal:
On 2020/07/03 13:05, Pavel Stehule wrote:
> Hi
>
> pá 3. 7. 2020 v 4:39 odesílatel Fujii Masao <[email protected]
<mailto:[email protected]> <mailto:[email protected]
<mailto:[email protected]>>> napsal:
>
>
>
> On 2020/07/01 7:37, Peter Geoghegan wrote:
> > On Tue, Jun 30, 2020 at 6:40 AM Fujii Masao <[email protected]
<mailto:[email protected]> <mailto:[email protected]
<mailto:[email protected]>>> 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.
Ok, so patch attached.
Regards,
--
Fujii Masao
Advanced Computing Technology Center
Research and Development Headquarters
NTT DATA CORPORATION
diff --git a/doc/src/sgml/pgstatstatements.sgml
b/doc/src/sgml/pgstatstatements.sgml
index 430d8bf07c..cf2d25b7b2 100644
--- a/doc/src/sgml/pgstatstatements.sgml
+++ b/doc/src/sgml/pgstatstatements.sgml
@@ -607,6 +607,9 @@
<para>
<varname>pg_stat_statements.track_planning</varname> controls whether
planning operations and duration are tracked by the module.
+ Enabling this parameter may incur a noticeable performance penalty,
+ especially when a fewer kinds of queries are executed on many
+ concurrent connections.
The default value is <literal>off</literal>.
Only superusers can change this setting.
</para>
