Hello Gilles. I made a silly mistake.
At Thu, 7 Nov 2019 09:05:55 +0100, Gilles Darold <gilles@darold.net> wrote in
> > FWIW, I see it a bit weird, too. And perhaps "prepare" should be in
> > upper case letters. 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.
>
>
> This is not what I've experienced, see the first message of the thread.
> A SELECT on foreign table prevent to use PREPARE TRANSACTION like with
> temporary table. Perhaps postgres_fdw should not throw an error with
> readonly queries on foreign tables but I guess that it is pretty hard to
> know especially on a later PREPARE event. But maybe I'm wrong, it is not
> easy every day :-) Can you share the SQL code you have executed to allow
> PREPARE transaction after a SELECT on a postgres_fdw foreign table?
Oooops!
After reading this, I came to be afraid that I did something wrong,
then I rechecked actual behavior. Finally I found that SELECT * FROM
foregn_tbl prohibits PREPARE TRANSACTION. I might have used a local
table instead of foreign tabel at the previous trial.
Sorry for the mistake and thank you for pointing it.
So my fixed proposals are:
"cannot PREPARE a transaction that has operated on foreign tables using postgres_fdw"
Or
"postgres_fdw doesn't support PREPARE of a transaction that has accessed foreign tables"
--
Kyotaro Horiguchi
NTT Open Source Software Center
