Re: Manual vacs 5x faster than autovacs?

From: Wayne Beaver <wayne(at)acedsl(dot)com>
To: Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: Manual vacs 5x faster than autovacs?
Date: 2009-11-16 16:13:49
Message-ID: 20091116111349.16951w20e4qpqdz4@www.aceinnovative.com
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> Quoting Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com>:
>
>> On Thu, Nov 12, 2009 at 9:58 AM, Wayne Beaver <wayne(at)acedsl(dot)com> wrote:
>>> Quoting Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com>:
>>>
>>>>> On Thu, Nov 12, 2009 at 9:14 AM, Wayne Beaver <wayne(at)acedsl(dot)com> wrote:
>>>>> I'd seen autovacs running for hours and had mis-attributed this to
>>>>> growing query times on those tables - my thought was that
>>>>> "shrinking" the tables
>>>>> "more quickly" could make them "more-optimized", more often. Sounds like
>>>>> could be chasing the wrong symptoms, though.
>>>>
>>>> Now it is quite possible that a slow autovac is causing your queries
>>>> to run slower.  So, if it has a moderate to high cost delay, then it
>>>> might not be able to keep
>>>> up with the job and your tables will become bloated.
>>>>
>>>> The problem isn't that autovac is stealing too many resources, it's
>>>> that it's not stealing enough.
>>>>
>> I've not yet gotten to you iostat inquiry from your previous response...
>
> Don't worry too much, just want to see if your IO system is maxed out.

$ iostat
Linux 2.6.18.8-0.9-default (myserver) 11/16/2009

avg-cpu: %user %nice %system %iowait %steal %idle
28.11 3.13 6.50 8.71 0.00 53.56

Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn
sda 153.08 7295.23 3675.59 123127895363 62036043656\

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