Re: Partial aggregates pushdown

On Thu, Oct 26, 2023 at 11:11:09AM +0000, Fujii(dot)Yuki(at)df(dot)MitsubishiElectric(dot)co(dot)jp wrote:
> > and checks if the remote server version is older than the local server version.
> > If so,
> > <filename>postgres_fdw</filename>
> > --> assumes that for each built-in aggregate function, the partial aggregate function is not defined
> > --> on the remote server unless the partial aggregate function and the aggregate
> > --> function match.
> > Otherwise <filename>postgres_fdw</filename> assumes that for each built-in aggregate function,
> > the partial aggregate function is defined on the remote server.
> > The default is <literal>false</literal>.
> > </para>
> > </listitem>
> > </varlistentry>
> >
> > What does that marked sentence mean? What is match? Are one or both of these remote? It sounds like you are
> > checking the local aggregate against the remote partial aggregate, but I don't see any code that does this in the patch.
> This sentence means that
> "If the partial aggregate function has the same OID as the aggregate function,
> then postgres_fdw assumes that for each built-in aggregate function, the partial aggregate function is not defined
> on the remote server."
> "Match" means that the partial aggregate function has the same OID as the aggregate function in local server.
> But, in v30, there is no code which checks the partial aggregate function has the same OID as the aggregate function in local server.
> So I modified the code of is_builtin_aggpartialfunc_shippable().
> Also, I modified wording postgres-fdw.sgml.

Yes, that is what I needed. Attached is a modification of your v31
patch (the most recent) that mostly improves the documentation and
comments. What else needs to be done before committers start to review
this?

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Bruce Momjian <bruce(at)momjian(dot)us> https://momjian.us
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