Re: compute_query_id and pg_stat_statements

On Tue, May 11, 2021 at 9:35 AM Julien Rouhaud <rjuju123@gmail.com> wrote:
>
> On Tue, May 11, 2021 at 03:04:13PM +0900, Michael Paquier wrote:
> > On Tue, Apr 27, 2021 at 02:25:04PM +0800, Julien Rouhaud wrote:
> > > On Mon, Apr 26, 2021 at 11:37:45AM -0700, Andres Freund wrote:
> > >> On 2021-04-26 14:21:00 -0400, Tom Lane wrote:
> > >>> That's sounding like a pretty sane design, actually.  Not sure about
> > >>> the shared-library-name-with-fixed-function-name detail, but certainly
> > >>> it seems to be useful to separate "I need a query-id" from the details
> > >>> of the ID calculation.
> > >>>
> > >>> Rather than a GUC per se for the ID provider, maybe we could have a
> > >>> function hook that defaults to pointing at the in-core computation,
> > >>> and then a module wanting to override that just gets into the hook.
> > >>
> > >> I have a preference to determining the provider via GUC instead of a
> > >> hook because it is both easier to introspect and easier to configure.
> >
> > So, this thread has died two weeks ago, and it is still an open item.
> > Could it be possible to move to a resolution by beta1?  The consensus
> > I can get from the thread is that we should have a tri-value state to
> > track an extra "auto" for the query ID computation, as proposed by
> > Alvaro here:
> > https://www.postgresql.org/message-id/20210426174331.GA19401@alvherre.pgsql
> >
> > Unfortunately, nothing has happened to be able to do something like
> > that.
>
> My understanding was that there wasn't a consensus on how to fix the problem.
>
> Anyway, PFA a patch that implement a [off | on | auto] compute_query_id, and
> provides a new queryIdWanted() function to let third party plugins inform us
> that they want a query id if possible.

30 second review -- wouldn't it be cleaner to keep a separate boolean
telling the backend "include it or not", which is set to true/false in
the guc assign hook and can then be flipped from false->true in
queryIdWanted()? (I'd suggest a more verbose name for that function
btw, something like requestQueryIdGeneration() or so).

(Again, just the 30 second review between meetings, so maybe I'm completely off)

-- 
 Magnus Hagander
 Me: https://www.hagander.net/
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