Re: PCTFree Results

Seems like this was to be somewhat expected. Was there any stats/diagnostics
included in the patch to show the effectiveness of PCTFREE?

On 9/22/05, Josh Berkus <josh(at)agliodbs(dot)com> wrote:
>
> Folks,
>
> Well, it took a while but I finally have the results of Satoshi's PCTFree
> patch back from the STP. Bad news about the STP, see below ...
>
> Anyway, a series of DBT2 runs doesn't seem to show any advantage to
> PCTFree
> over a 3-hour run with no vacuums:
>
> test# pctfree full_page_writes notpm
> 303164 off off 1803
> 303165 on on 1847
> 303166 on off 1860
> 303167 off on 1801
> 303168 off off 1838
> 303169 on on 1821
> 303170 on off 1846
>
> (again, check all results at http://www.testing.osdl.org/stp/######/)
>
> The differences above are small enough to be in the "noise" factor of DBT2
> execution. The good news is that it appears that stuff which has been
> done since July has lessened the penalty for checkpoints somewhat; while
> the maximum response time is still better on the full_page_writes=off
> systems, the average throughput is no longer substantially different.
> Either that, or full_page_writes=off isn't working properly anymore.
>
> If anyone has suggestions on different tests to run, or better stats to
> compile, please speak up.
>
> Now, the bad news: the STP has had some failures and is down to *one*
> usable machine for testing. I have, like, 160 performance tests backed up
> which are never going to get run before we release 8.1. I'm going to be
> hitting up some major PostgreSQL sponsors for hardware donations, any help
> is welcome.
>
> --
> --Josh
>
> Josh Berkus
> Aglio Database Solutions
> San Francisco
>
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--
Respectfully,

Jonah H. Harris, Database Internals Architect
EnterpriseDB Corporation
http://www.enterprisedb.com/