Re: 9.2 documentation/configuration question

-----Original Message-----
From: pgsql-admin-owner@postgresql.org [mailto:pgsql-admin-owner@postgresql.org] On Behalf Of John Scalia
Sent: Tuesday, December 02, 2014 3:00 PM
To: pgsql-admin@postgresql.org
Subject: [ADMIN] 9.2 documentation/configuration question

Hi All,

I've been asked to assist another group in our company and their db configuration is a little confusing to me. The
databaseis not replicated, but it is running WAL archiving. I've been looking at
http://www.postgresql.org/docs/9.2/static/wal-configuration.htmland my confusion regards the 4th paragraph: 

"The server's checkpointer process automatically performs a checkpoint every so often. A checkpoint is created every
checkpoint_segmentslog segments, or every checkpoint_timeout seconds, whichever comes first. The default settings are 3
segmentsand 300 seconds (5 minutes), respectively. In cases where no WAL has been written since the previous
checkpoint,new checkpoints will be skipped even if checkpoint_timeout has passed. If WAL archiving is being used and
youwant to put a lower limit on how often files are archived in order to bound potential data loss, you should adjust
archive_timeoutparameter rather than the checkpoint parameters..." 

So, are docs saying that checkpoint_timeout is ignored if you have a value for archive_timeout or is it still used?
Thisserver currently has: 
checkpoint_segments=32
checkpoint_timeout = 5min #default
archive_timeout=3600

and I'm not sure these make sense together in light of this paragraph.
--
Jay


No, documentation says that even if WAL was not written, WAL archive will be created on archive_timeout, in your case
atleast once per hour. 

Regards,
Igor Neyman