Re: Feature improvement: can we add queryId for pg_catalog.pg_stat_activity view?

On Wed, Oct  7, 2020 at 10:42:49AM +0900, Michael Paquier wrote:
> On Tue, Oct 06, 2020 at 09:22:29AM -0400, Bruce Momjian wrote:
> > I propose moving the pg_stat_statements queryid hash code into the
> > server (with a version number), and also adding a postgresql.conf
> > variable that lets you control how detailed the queryid hash is
> > computed.  This addresses the problem of people wanting different hash
> > methods.
> 
> In terms of making this part expendable in the future, there could be
> a point in having an enum here, but are we sure that we will have a
> need for that in the future?  What I get from this discussion is that
> we want a unique source of truth that users can consume, and that the
> only source of truth proposed is the PGSS hashing.  We may change the
> way we compute the query ID in the future, for example if it gets
> expanded to some utility statements, etc.  But that would be
> controlled by the version number in the hash, not the GUC itself.

Oh, if that is true, then I agree let's just go with the version number.

> > When computing a hash, the queryid detail level and version number will
> > be mixed into the hash, so only a hash that used a similar query and
> > identical queryid detail level would match.
> 
> Yes, having a version number directly dependent on the hashing sounds
> like a good compromise to me.

Good, much simpler.  I think there is enough demand for a queryid that I
would like to get this moving forward.

-- 
  Bruce Momjian  <bruce@momjian.us>        https://momjian.us
  EnterpriseDB                             https://enterprisedb.com

  The usefulness of a cup is in its emptiness, Bruce Lee