Re: Fix error message for MERGE foreign tables

On 2022-Oct-14, Michael Paquier wrote:

> On Fri, Oct 14, 2022 at 12:26:19PM +0800, Richard Guo wrote:
> > Maybe something like below, so that we keep it consistent with the case
> > of a foreign table being specified as a target.
> > 
> > --- a/contrib/postgres_fdw/postgres_fdw.c
> > +++ b/contrib/postgres_fdw/postgres_fdw.c
> > @@ -1872,6 +1872,13 @@ postgresPlanForeignModify(PlannerInfo *root,
> >                              returningList,
> >                              &retrieved_attrs);
> >             break;
> > +       case CMD_MERGE:
> > +           ereport(ERROR,
> > +                   (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
> > +                    errmsg("cannot execute MERGE on relation \"%s\"",
> > +                           RelationGetRelationName(rel)),
> > +
> >  errdetail_relkind_not_supported(rel->rd_rel->relkind)));
> > +           break;
> 
> Yeah, you should not use an elog(ERROR) for cases that would be faced
> directly by users.

Yeah, I think this just flies undetected until it hits code that doesn't
support the case.  I'll add a test and push as Richard suggests, thanks.

-- 
Álvaro Herrera        Breisgau, Deutschland  —  https://www.EnterpriseDB.com/
"La libertad es como el dinero; el que no la sabe emplear la pierde" (Alvarez)