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Re: pgbench Comparison of 7.4.7 to 8.0.2

From: Steve Poe <spoe(at)sfnet(dot)cc>
To: "Thomas F(dot)O'Connell" <tfo(at)sitening(dot)com>
Cc: PgSQL - Performance <pgsql-performance(at)postgresql(dot)org>
Subject: Re: pgbench Comparison of 7.4.7 to 8.0.2
Date: 2005-04-25 17:18:23
Message-ID: 426D265F.9080902@sfnet.cc (view raw or flat)
Thread:
Lists: pgsql-performance
Tom,

Just a quick thought: after each run/sample of pgbench, I drop the 
database and recreate it. When I don't my results become more skewed.

Steve Poe


Thomas F.O'Connell wrote:

> Interesting. I should've included standard deviation in my pgbench 
> iteration patch. Maybe I'll go back and do that.
>
> I was seeing oscillation across the majority of iterations in the 25 
> clients/1000 transaction runs on both database versions.
>
> I've got my box specs and configuration files posted. If you see 
> anything obvious about the tuning parameters that should be tweaked, 
> please let me know.
>
> Thanks for the feedback!
>
> -tfo
>
> -- 
> Thomas F. O'Connell
> Co-Founder, Information Architect
> Sitening, LLC
>
> Strategic Open Source: Open Your iâ„¢
>
> http://www.sitening.com/
> 110 30th Avenue North, Suite 6
> Nashville, TN 37203-6320
> 615-260-0005
>
> On Apr 25, 2005, at 1:58 AM, Steve Poe wrote:
>
>> >There was some interesting oscillation behavior in both version of 
>> postgres that occurred with 25 >clients and 1000 transactions at a 
>> scaling factor of 100. This was repeatable with the distribution 
>> >version of pgbench run iteratively from the command line. I'm not 
>> sure how to explain this.
>>
>> Tom,
>>
>> When you see these oscillations, do they occur after so many 
>> generated results? Some oscillation is normal, in my opinion, from 
>> 10-15% of the performance is noise-related.
>>
>> The key is to tune the server that you either 1) minimize the 
>> oscillation and/or 2)increase your overall performance above the 
>> 10-15% baseline, and 3) find out what the mean and standard deviation 
>> between all your results.
>>
>> If your results are within that range, this maybe "normal". I 
>> follow-up with you later on what I do.
>>
>> Steve Poe
>
>
>


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