Re: Expression errors with "FOR UPDATE" and postgres_fdw with partition wise join enabled.

On Wed, Feb 14, 2018 at 2:50 PM, Etsuro Fujita
<fujita(dot)etsuro(at)lab(dot)ntt(dot)co(dot)jp> wrote:
>
> I'd vote for #1, but ISTM that that's more like a feature, not a fix.
> Pushing down ConvertRowtypeExprs to the remote seems to me to be the same
> problem as pushing down PHVs to the remote, which is definitely a feature
> development. I think a fix for this would be to just give up pushing down a
> child join in foreign_join_ok or somewhere else if the reltarget of the
> child-join relation contains any ConvertRowtypeExprs.

That means we won't be able to push down any scans under a DML on a
partitioned table. That will be too restrictive.

I think the case of PHV and ConvertRowtypeExprs are different. The the
former we need a subquery to push PHVs, whereas to deparse
ConvertRowtypeExpr on the nullable side we can use the same strategy
as whole-row expression deparsing.

--
Best Wishes,
Ashutosh Bapat
EnterpriseDB Corporation
The Postgres Database Company