Re: How can you get "WAL segment has already been removed" when doing synchronous replication ?!

On Thu, Jul 11, 2013 at 11:29:24PM +0530, Raghavendra wrote:
> On Thu, Jul 11, 2013 at 11:18 PM, hubert depesz lubaczewski <
> depesz@depesz.com> wrote:
>
> > We are seeing situation like this:
> > 1. 9.2.4 database
> > 2. Master settings:
> >            name            |    setting
> > ---------------------------+---------------
> >  fsync                     | on
> >  synchronize_seqscans      | on
> >  synchronous_commit        | remote_write
> >  synchronous_standby_names | *
> >  wal_sync_method           | open_datasync
> > (5 rows)
> >
> > Yet, every now and then we're getting:
> > FATAL:  requested WAL segment * has already been removed
> >
> > Assuming no part of the system is issuing "set synchronous_commit
> > = off", how can we get in such situation?
> >
> > Best regards,
> >
> > depesz
> >
> >
> Increasing the wal_keep_segments ?

I know that I can increase wal_keep_segments to "solve" it, but
shouldn't it be *impossible* to happen with synchronous replication?
After all - all commits should wait for slave to be 100% up to date!

Best regards,

depesz