| From: | Dan Harris <fbsd(at)drivefaster(dot)net> |
|---|---|
| To: | pgsql-performance <pgsql-performance(at)postgresql(dot)org> |
| Subject: | Re: Slow count(*) again... |
| Date: | 2010-10-12 15:39:19 |
| Message-ID: | 4CB48127.6090200@drivefaster.net |
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| Lists: | pgsql-hackers pgsql-performance |
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
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