[pgpool-general: 6250] Re: Online Recovery vs WAL acrhiving

Tatsuo Ishii ishii at sraoss.co.jp
Sat Oct 20 11:01:36 JST 2018

> It seems that online recovery scripts take base backup of the primary
> to recover downed node.
> With streaming replication and WAL archiving enabled downed node can
> be recovered when it is started again much faster than taking entire
> base backup of the primary.
> So question comes to mind, what is the advantage of using
> time-consuming online recovery over WAL archiving restore process?
> Is attaching downed node to PgPool automatically the only benefit?

If you are sure that the downed node can be recovered by fetching WAL
from archive at its starting up, you don't need to use online recovery
at all. You just start the standby and issue pcp_attach_node is
enough (assuming that the standby node was once attached to

On the other hand, if the downed node cannot be recovered due to its
database corruption or some other problems, you have to copy primary
database to standby, and that's what online recovery usually does.
Another scenario is adding brand new standby. In this case you need
fully copy primary database anyway and you should use on line

Best regards,
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php

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