Message-ID: <4CBDE169.4060008@agliodbs.com>
Date: Tue, 19 Oct 2010 11:20:25 -0700
From: Josh Berkus <josh@agliodbs.com>
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To: Greg Stark <gsstark@mit.edu>
CC: pgsql-hackers@postgresql.org
Subject: Re: Simplifying replication
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Greg,

> The way things stand you *always* need archived logs. Even if you have
> streaming set up it might try to use archived logs if it falls too far
> behind.

Actually, you don't.  If you're willing to accept possible
desynchronization and recloning of the standbys, then you can skip the
archive logs.

> Timelines are not as obvious but perhaps that's our own mistake. When
> you fail over to your replica shouldn't the new master get a new
> timelineid? Isn't that the answer to the failure case when a slave
> finds it's ahead of the master? If it has already replayed logs from a
> different timelineid in the same lsn range then it can't switch
> timelines to follow the new master. But if it hasn't then it can.

Oh?  Do we have this information (i.e. what LSNs are associated with
which timeline)?


-- 
                                  -- Josh Berkus
                                     PostgreSQL Experts Inc.
                                     http://www.pgexperts.com