Re: archive_timeout behaviour when archive_mode is off (was Re: [HACKERS] Too frequent checkpoints ?)

2013-02-15 Thread Fujii Masao
On Fri, Feb 15, 2013 at 3:12 PM, Pavan Deolasee
pavan.deola...@gmail.com wrote:
 (changing subject)

 On Thu, Feb 14, 2013 at 11:48 PM, Fujii Masao masao.fu...@gmail.com wrote:
 On Mon, Feb 11, 2013 at 5:46 PM, Pavan Deolasee
 I also noticed that the WAL file switch
 happens after archive_timeout seconds irrespective of whether
 archive_mode is turned ON or not. This happens because we don't check
 if XLogArchivingActive() in CheckArchiveTimeout() function. It looks
 wrong to me.

 +1 to fix this. I've not heard the use case where archive_timeout needs to
 be used even in not archive mode...

 Ok, I will write a patch to fix this. I wonder if this is worth
 backpatching though. The code is like that for a long time and the
 fact that we haven't heard any complaints about it, may be its not
 worth fixing in the stable branches. But I wonder if anyone else
 thinks otherwise.

On second thought, there might be the use case. Imagine the case where
you disable archive_mode and instead use pg_receivexlog for WAL archiving
purpose. WAL records are streamed from the server to pg_receivexlog in
realtime, so basically archive_timeout is not required to be set in this case.
But you might need to periodically verify the correctness of the connection
between the server and pg_receivexlog. You can do that by checking whether
new WAL file has been streamed since last check. But if there is no activity
in the server, you cannot use that verification method. In this case,
archive_timeout is useful even when archive_mode is not enabled.

This is very narrow case, but as you said, we haven't heard any complaints
about it, so I'm inclined not to fix it

Regards,

-- 
Fujii Masao


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archive_timeout behaviour when archive_mode is off (was Re: [HACKERS] Too frequent checkpoints ?)

2013-02-14 Thread Pavan Deolasee
(changing subject)

On Thu, Feb 14, 2013 at 11:48 PM, Fujii Masao masao.fu...@gmail.com wrote:
 On Mon, Feb 11, 2013 at 5:46 PM, Pavan Deolasee
 I also noticed that the WAL file switch
 happens after archive_timeout seconds irrespective of whether
 archive_mode is turned ON or not. This happens because we don't check
 if XLogArchivingActive() in CheckArchiveTimeout() function. It looks
 wrong to me.

 +1 to fix this. I've not heard the use case where archive_timeout needs to
 be used even in not archive mode...


Ok, I will write a patch to fix this. I wonder if this is worth
backpatching though. The code is like that for a long time and the
fact that we haven't heard any complaints about it, may be its not
worth fixing in the stable branches. But I wonder if anyone else
thinks otherwise.

I think we should also update the documentation to be clear that
archive_timeout and archive_command are used only when archive_mode is
turned on.

Thanks,
Pavan

-- 
Pavan Deolasee
http://www.linkedin.com/in/pavandeolasee


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