Re: Manual vacs 5x faster than autovacs? - Mailing list pgsql-performance

From Wayne Beaver
Subject Re: Manual vacs 5x faster than autovacs?
Date
Msg-id 20091116120205.83541j9h3okizkpw@www.aceinnovative.com
Whole thread Raw
In response to Re: Manual vacs 5x faster than autovacs?  (Scott Marlowe <scott.marlowe@gmail.com>)
List pgsql-performance
Quoting Scott Marlowe <scott.marlowe@gmail.com>:

> On Mon, Nov 16, 2009 at 9:13 AM, Wayne Beaver <wayne@acedsl.com> wrote:
>>> Quoting Scott Marlowe <scott.marlowe@gmail.com>:
>>>
>>>> On Thu, Nov 12, 2009 at 9:58 AM, Wayne Beaver <wayne@acedsl.com> wrote:
>>>>>
>>>>> Quoting Scott Marlowe <scott.marlowe@gmail.com>:
>>>>>
>>>>>>> On Thu, Nov 12, 2009 at 9:14 AM, Wayne Beaver <wayne@acedsl.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.
>>
>
> That's just since the machine was turned on.  run it like:
>
> iostat -x 10
>
> and see what comes out after the first one.


Duh! Sorry about that...


$ iostat -x 10
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    8.70    0.00   53.56

Device:    rrqm/s wrqm/s   r/s   w/s  rsec/s  wsec/s    rkB/s    wkB/s
avgrq-sz avgqu-sz   await  svctm  %util
sda          3.20 406.34 100.74 52.33 7293.84 3675.79  3646.92
1837.90    71.66     0.07    2.15   0.90  13.71

pgsql-performance by date:

Previous
From: Scott Marlowe
Date:
Subject: Re: Manual vacs 5x faster than autovacs?
Next
From: Dave Crooke
Date:
Subject: Re: Unexpected sequential scan on an indexed column