Re: Transactions involving multiple postgres foreign servers, take 2

On Fri, Jun 12, 2020 at 7:59 AM Masahiko Sawada
<masahiko.sawada@2ndquadrant.com> wrote:
>
> On Thu, 11 Jun 2020 at 22:21, Amit Kapila <amit.kapila16@gmail.com> wrote:
> >
>
> >  I have another question about
> > this field, why can't it be one of the status ('preparing',
> > 'prepared', 'committing', 'aborting', 'in-doubt') rather than having a
> > separate field?
>
> Because I'm using in-doubt field also for checking if the foreign
> transaction entry can also be resolved manually, i.g.
> pg_resolve_foreign_xact(). For instance, a foreign transaction which
> status = 'prepared' and in-doubt = 'true' can be resolved either
> foreign transaction resolver or pg_resolve_foreign_xact(). When a user
> execute pg_resolve_foreign_xact() against the foreign transaction, it
> sets status = 'committing' (or 'rollbacking') by checking transaction
> status in clog. The user might cancel pg_resolve_foreign_xact() during
> resolution. In this case, the foreign transaction is still status =
> 'committing' and in-doubt = 'true'. Then if a foreign transaction
> resolver process processes the foreign transaction, it can commit it
> without clog looking.
>

I think this is a corner case and it is better to simplify the state
recording of foreign transactions then to save a CLOG lookup.

-- 
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com