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

From Marc G. Fournier
Subject Re: 2-phase commit
Date
Msg-id 20030929105527.D632@ganymede.hub.org
Whole thread Raw
In response to Re: 2-phase commit  (Hiroshi Inoue <Inoue@tpf.co.jp>)
Responses Re: 2-phase commit  (Bruce Momjian <pgman@candle.pha.pa.us>)
List pgsql-hackers

On Mon, 29 Sep 2003, Hiroshi Inoue wrote:

>
>
> Hiroshi Inoue wrote:
> >
> > Tom Lane wrote:
> > >
> > > Hiroshi Inoue <Inoue@tpf.co.jp> writes:
> > > > The simplest senario(though there could be varations) is
> > >
> > > > [At participant(master)'s side]
> > > >   Because the commit operations is done, does nothing.
> > >
> > > > [At coordinator(slave)' side]
> > > >    1) After a while
> > > >    2) re-establish the communication path between the
> > > >       partcipant(master)'s TM.
> > > >    3) resend the "commit requeset" to the participant's TM.
> > > >   1)2)3) would be repeated until the coordinator receives
> > > >   the "commit ok" message from the partcipant.
> > >
> > > [ scratches head ] I think you are using the terms "master" and "slave"
> > > oppositely than I would.
> >
> > Oops my mistake, sorry.
> > But is it 2-phase commit protocol in the first place ?
>
> That is, in your exmaple below
>
>  Example:
>
>         Master          Slave
>         ------          -----
>         commit ready-->
>                         <--OK
>         commit done->XX
>
> is the "commit done" message needed ?

Of course ... how else will the Slave commit?  From my understanding, the
concept is that the master sends a commit ready to the slave, but the OK
back is that "OK, I'm ready to commit whenever you are", at which point
the master does its commit and tells the slave to do its ...



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