Re: compute_query_id and pg_stat_statements

On Mon, Apr 26, 2021 at 05:34:30PM +0200, Christoph Berg wrote:
> Re: Peter Eisentraut
> > > Agreed. If pg_stat_statements were zero-configuration today then
> > > this would be an annoying new burden, but it isn't.
> >
> > I think people can understand "add pg_stat_statements to
> > shared_preload_libraries" and "install the extension". You have to turn it
> > on somehow after all.
>
> Fwiw, I'd claim that pg_stat_statements *is* zero-configuration today.
> You just have to load the module (= shared_preload_libraries), and it
> will start working. Later you can run CREATE EXTENSION to actually see
> the stats, but they are already being collected in the background.
>
> > Now there is the additional burden of turning on this weird setting that no
> > one understands. That's a 50% increase in burden.
> >
> > And almost no one will want to use a nondefault setting.
> >
> > pg_stat_statements is pretty popular. I think leaving in this requirement
> > will lead to widespread confusion and complaints.
>
> Ack, please make the default config (i.e. after setting shared_preload_libraries)
> do something sensible. Having to enable some "weird" internal other setting
> will be very hard to explain to users.
>
> Fwiw, I'd even want to have pg_stat_statements enabled in core by
> default. That would awesome UX. (And turning off could be as simple as
> setting compute_query_id=off.)

Techically, pg_stat_statements can turn on compute_query_id when it is
loaded, even if it is 'off' in postgresql.conf, right? And
pg_stat_statements would know if an alternate hash method is being used,
right?

This is closer to Magnus's idea of having a three-value
compute_query_id, except is it more controlled by pg_stat_statements.
Another idea would be to throw a user-visible warning if the
pg_stat_statements extension is loaded and compute_query_id is off.

--
Bruce Momjian <bruce(at)momjian(dot)us> https://momjian.us
EDB https://enterprisedb.com

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