Re: track_planning causing performance regression

On Wed, Apr 21, 2021 at 11:38:52PM +0900, Fujii Masao wrote:
> On 2021/04/19 23:55, Justin Pryzby wrote:
> > What does "kind" mean ? I think it means a "normalized" query or a "query
> > structure".
> >
> > "a fewer kinds" is wrong, so I think the docs should say "a small number of
> > queries" or maybe:
>
> Okay, I agree to update the description.
>
> > > > > Enabling this parameter may incur a noticeable performance penalty,
> > > > > especially similar queries are run by many concurrent connections and
> > > > > compete to update the same pg_stat_statements entry
>
> "a small number of" is better than "similar" at the above because
> "similar" sounds a bit unclear in this case?
>
> It's better to use "entries" rather than "entry" at the above?

How about like this?

Enabling this parameter may incur a noticeable performance penalty,
- especially when a fewer kinds of queries are executed on many
+ especially when queries with the same queryid are executed by many
concurrent connections.

Or:

Enabling this parameter may incur a noticeable performance penalty,
especially similar queries are executed by many concurrent connections
and compete to update a small number of pg_stat_statements entries.

--
Justin