From: Neil Whelchel <neil.whelchel@gmail.com>
To: pgsql-performance@postgresql.org
Subject: Re: Slow count(*) again...
Date: Tue, 12 Oct 2010 15:33:33 -0700
Message-ID: <201010121533.34047.neil.whelchel@gmail.com> (raw)
In-Reply-To: <4CB48127.6090200@drivefaster.net>
References: <201010091626.18636.neil.whelchel@gmail.com>
<90E30938-1E5E-4DCA-A1FB-AEECEB76A70D@richrelevance.com>
<4CB48127.6090200@drivefaster.net>
On Tuesday 12 October 2010 08:39:19 Dan Harris wrote:
> On 10/11/10 8:02 PM, Scott Carey wrote:
> > would give you a 1MB read-ahead. Also, consider XFS and its built-in
> > defragmentation. I have found that a longer lived postgres DB will get
> > extreme file fragmentation over time and sequential scans end up mostly
> > random. On-line file defrag helps tremendously.
>
> We just had a corrupt table caused by an XFS online defrag. I'm scared
> to use this again while the db is live. Has anyone else found this to
> be safe? But, I can vouch for the fragmentation issue, it happens very
> quickly in our system.
>
> -Dan
I would like to know the details of what was going on that caused your
problem. I have been using XFS for over 9 years, and it has never caused any
trouble at all in a production environment. Sure, I had many problems with it
on the test bench, but in most cases the issues were very clear and easy to
avoid in production. There were some (older) XFS tools that caused some
problems, but that is in the past, and as time goes on, it seems take less and
less planning to make it work properly.
-Neil-
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To: pgsql-performance@postgresql.org
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Subject: Re: Slow count(*) again...
In-Reply-To: <201010121533.34047.neil.whelchel@gmail.com>
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