Re: postgres_fdw: Add support for INSERT OVERRIDING clause

On Tue, Oct 31, 2017 at 3:45 PM, Peter Eisentraut
<peter(dot)eisentraut(at)2ndquadrant(dot)com> wrote:
> It has been pointed out to me that the command deparsing in postgres_fdw
> does not support the INSERT OVERRIDING clause that was added in PG10.
> Here is a patch that seems to fix that. I don't know much about this,
> whether anything else needs to be added or whether there should be
> tests. Perhaps someone more familiar with postgres_fdw details can
> check it.

Trying to insert some data using OVERRIDING SYSTEM VALUE on a foreign
table with a remote relation defined with GENERATED ALWAYS would just
fail:
=# insert into id_always_foreign OVERRIDING system VALUE values (8);
ERROR: 428C9: cannot insert into column "a"
DETAIL: Column "a" is an identity column defined as GENERATED ALWAYS.
HINT: Use OVERRIDING SYSTEM VALUE to override.

And that's confusing because there is no actual way to avoid this
error if postgres_fdw is unpatched.

I think that you should add some tests, and make sure that the
documentation of postgres-fdw.sgml mentions that those two clauses are
pushed down.
--
Michael