Re: [PATCH][DOC] Fix for PREPARE TRANSACTION doc and postgres_fdw message.

Horiguchi-san,

On Thu, Nov 7, 2019 at 4:11 PM Kyotaro Horiguchi
<horikyota(dot)ntt(at)gmail(dot)com> wrote:
> At Wed, 6 Nov 2019 20:13:10 +0900, Etsuro Fujita <etsuro(dot)fujita(at)gmail(dot)com> wrote in
> > On Wed, Nov 6, 2019 at 4:35 PM Michael Paquier <michael(at)paquier(dot)xyz> wrote:
> > > On Wed, Nov 06, 2019 at 03:12:04PM +0900, Etsuro Fujita wrote:
> > > > On Wed, Nov 6, 2019 at 1:13 PM Michael Paquier <michael(at)paquier(dot)xyz> wrote:
> > > >> "postgres_fdw foreign tables" sounds weird to me. Could "foreign
> > > >> tables using postgres_fdw" be a better wording? I am wondering as
> > > >> well if we should not split this information into two parts: one for
> > > >> the actual error message which only mentions foreign tables, and a
> > > >> second one with a hint to mention that postgres_fdw has been used.
> > > >
> > > > We use "postgres_fdw foreign tables" or "postgres_fdw tables" in
> > > > release notes, so I thought it was OK to use that in error messages as
> > > > well. But actually, these wordings are not suitable for error
> > > > messages?
> > >
> > > It is true that the docs of postgres_fdw use that and that it is used
> > > in some comments. Still, I found this wording a bit weird.. If you
> > > think that what you have is better, I am also fine to let you have the
> > > final word, so please feel to ignore me :)
> >
> > I'd like to hear the opinions of others.
>
> FWIW, I see it a bit weird, too.

Only two people complaining about the wording? Considering as well
that we use that wording in the docs and there were no complains about
that IIRC, I don't feel a need to change that, TBH.

> And perhaps "prepare" should be in
> upper case letters.

Seems like a good idea.

> Plus, any operation including a SELECT on a
> temporary table inhibits PREAPRE TRANSACTION, but the same on a
> postgres_fdw foreign tables is not. So the error message is rather
> wrong.
>
> A verbose alternative can be:
>
> "cannot PREPARE a transaction that has modified data on foreign tables using postgres_fdw"

I don't think that's better, because that doesn't address the original
issue reported in this thread, as Gilles pointed out just before in
his email. See the commit message in the patch I posted.

Thanks for the comments!

Best regards,
Etsuro Fujita