On 04.12.2010 04:18, Tatsuo Ishii wrote:
There is a description about streaming replication in the doc:
----------------------------------------------------------
25.2.5. Streaming Replication
:
:
If you set up a WAL archive that's accessible from the
standby, wal_keep_segments is not required as the standby can always
use the archive to catch up.
----------------------------------------------------------
I think this description is somewhat inadequate. Since recovery using
WAL archive is file based, it may cause long replication delay. I
think even if WAL archive is set up, we should set wal_keep_segments
to proper value, not 0. Recovery from WAL archive should be the last
resort, shouldn't be?
If your standby falls behind that much, catching up is going to take a
while anyway. The master always keeps 2-3 * checkpoint_segments WAL
segments around anyway even if wal_keep_segments is 0.
Depending on the archive, it might well be faster to catch up using the
archive, instead of streaming from master.
--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com
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