Re: Ideas about a better API for postgres_fdw remote estimates

On Sat, Aug 29, 2020 at 12:50:59PM -0400, Tom Lane wrote:
> Stephen Frost <sfrost(at)snowman(dot)net> writes:
> > Isn't this going to create a version dependency that we'll need to deal
> > with..? What if a newer major version has some kind of improved ANALYZE
> > command, in terms of what it looks at or stores, and it's talking to an
> > older server?
>
> Yeah, this proposal is a nonstarter unless it can deal with the remote
> server being a different PG version with different stats.
>
> Years ago (when I was still at Salesforce, IIRC, so ~5 years) we had
> some discussions about making it possible for pg_dump and/or pg_upgrade
> to propagate stats data forward to the new database. There is at least
> one POC patch in the archives for doing that by dumping the stats data
> wrapped in a function call, where the target database's version of the
> function would be responsible for adapting the data if necessary, or
> maybe just discarding it if it couldn't adapt. We seem to have lost
> interest but it still seems like something worth pursuing. I'd guess
> that if such infrastructure existed it could be helpful for this.

I don't think there was enough value to do statistics migration just for
pg_upgrade, but doing it for pg_upgrade and FDWs seems like it might
have enough demand to justify the required work and maintenance.

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

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