Re: A 2 phase commit weirdness - Mailing list pgsql-hackers

From Alvaro Herrera
Subject Re: A 2 phase commit weirdness
Date
Msg-id 20050531124448.GA5451@surnet.cl
Whole thread Raw
In response to Re: A 2 phase commit weirdness  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: A 2 phase commit weirdness  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
On Tue, May 31, 2005 at 02:09:56AM -0400, Tom Lane wrote:
> Alvaro Herrera <alvherre@surnet.cl> writes:
> > But at awakening, the user will get this:
> > ERROR:  relation 66002 deleted while still in use
> > This is ugly -- I don't think there is a way to get out of it.
> 
> There had better be a way, since (I suppose) the ERROR is preventing the
> commit from succeeding ...

No, the ERROR is in a completely unrelated transaction.  The scenario
again is this:

CREATE TABLE foo ();

BEGIN;
DROP TABLE foo;
PREPARE TRANSACTION 'foo';

            SELECT * FROM foo;            -- hangs
COMMIT TRANSACTION 'foo';            ERROR, relation deleted while still in            use

So it's a rather contorted situation to begin with.

> > Unrelated question: is it intended that the prepared transactions are
> > visible cross-database through pg_prepared_xacts?
> 
> That is a good question.  Can a backend running in a different database
> execute the COMMIT (or ROLLBACK)?  Offhand I'd bet that will not work,
> which suggests we'd better make the view per-database.  [ thinks a bit
> more... ]  We might be able to make it work, but there seems like a lot
> of potential for bugs/fragility there.  Might be best to take the narrow
> definition to start with.

Ok.

-- 
Alvaro Herrera (<alvherre[a]surnet.cl>)
"El sentido de las cosas no viene de las cosas, sino de
las inteligencias que las aplican a sus problemas diarios
en busca del progreso." (Ernesto Hernández-Novich)


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