On Thu, Nov 13, 2014 at 10:05 AM, Heikki Linnakangas <hlinnakan...@vmware.com> wrote: >> In this case the >> old master will request recovery from a point after the timeline >> switch and the new master will reply with an error. So it is safe to >> try re-adding a crashed master as a slave, but this might fail. > > > Are you sure it's guaranteed to fail, when the master had some WAL that was > not streamed before the crash? I'm not 100% sure about that. I thought the > old master might continue streaming and replaying, if there just happens to > be a record start at the same point in WAL on both timelines. I think you'll > get an error at the next checkpoint record, because its timeline ID isn't > what the old master expects, but it would've started up already.
It seems to me like it's guaranteed. Given slave promotion at x1 and end of xlog on old master at x2, x1 < x2, master will request streaming at tli1.x2, wal sender does tliSwitchPoint(tli1) to lookup x1, finds that x1 < x2 and gives the error "requested starting point %X/%X on timeline %u is not in this server's history". The alignment of x2 on tli2 does not play a role here. Regards, Ants Aasma -- Cybertec Schönig & Schönig GmbH Gröhrmühlgasse 26 A-2700 Wiener Neustadt Web: http://www.postgresql-support.de -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
