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Re: a heavy duty operation on an "unused" table kills my server

From: Andy Colson <andy(at)squeakycode(dot)net>
To: Craig Ringer <craig(at)postnewspapers(dot)com(dot)au>, pgsql-performance(at)postgresql(dot)org
Subject: Re: a heavy duty operation on an "unused" table kills my server
Date: 2010-01-14 14:49:36
Message-ID: 4B4F2F00.7070401@squeakycode.net (view raw or flat)
Thread:
Lists: pgsql-performance
On 1/13/2010 11:36 PM, Craig Ringer wrote:
> Robert Haas wrote:
>
>> I'm kind of surprised that there are disk I/O subsystems that are so
>> bad that a single thread doing non-stop I/O can take down the whole
>> server.  Is that normal?
>
> No.
>
>> Does it happen on non-Windows operating
>> systems?
>
> Yes. My 3ware 8500-8 on a Debian Sarge box was so awful that launching a
> terminal would go from a 1/4 second operation to a 5 minute operation
> under heavy write load by one writer. I landed up having to modify the
> driver to partially mitigate the issue, but a single user on the
> terminal server performing any sort of heavy writing would still
> absolutely nuke performance.

On a side note, on linux, would using the deadline scheduler resolve that?

-Andy

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Subject: Slow "Select count(*) ..." query on table with 60 Mio. rows
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