Message-ID: <4DB21BFA.4030800@consistentstate.com>
Date: Fri, 22 Apr 2011 18:23:22 -0600
From: Brian Fehrle <brianf@consistentstate.com>
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To: pgsql-admin@postgresql.org
CC: Kevin Kempter <kevink@consistentstate.com>
Subject: archive_timeout behavior (8.4.6)
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Hi all,
     We thought we were having issues with our warm standby (postgres 
8.4.6), but think we figured it out, however I'd like someone to confirm 
what we think is true.

If a cluster has zero activity whatsoever, but we have archive_timeout 
set (say to 60 seconds), will it create a WAL file anyways, or knowing 
there was zero activity does it skip it? We turned it on (temporarily) 
to force WAL files to go to a newly set up warm standby so we could 
verify that we have the whole end-to-end process correct, but we didn't 
have any WAL files transfer to the warm standby. After some trouble 
shooting, we notice that we do get a WAL file shortly after we insert a 
single row into a table.

The confusion is probably because I remember this same scenario on older 
versions of 8.4, and watching it generate wal files even with no activity.

So long story short, if a cluster has zero activity, and archive_timeout 
is not set to 0, when it reaches that timeout should it generate a file, 
or just skip because it would be 100% empty?


Thanks in advance,
     Brian F