Re: Response time increases over time - Mailing list pgsql-performance

From Marti Raudsepp
Subject Re: Response time increases over time
Date
Msg-id CABRT9RC+iRXhvA4KCeR3+hoh179WKyc1QNicpPBD1NbzM4RYdA@mail.gmail.com
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In response to Re: Response time increases over time  (Aidan Van Dyk <aidan@highrise.ca>)
Responses Re: Response time increases over time  (Havasvölgyi Ottó <havasvolgyi.otto@gmail.com>)
List pgsql-performance
On Thu, Dec 8, 2011 at 06:37, Aidan Van Dyk <aidan@highrise.ca> wrote:
> Let me guess, debian squeeze, with data and xlog on both on a single
> ext3 filesystem, and the fsync done by your commit (xlog) is flushing
> all the dirty data of the entire filesystem (including PG data writes)
> out before it can return...

This is fixed with the data=writeback mount option, right?
(If it's the root file system, you need to add
rootfsflags=data=writeback to your kernel boot flags)

While this setting is safe and recommended for PostgreSQL and other
transactional databases, it can cause garbage to appear in recently
written files after a crash/power loss -- for applications that don't
correctly fsync data to disk.

Regards,
Marti

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