Re: FYI: Load times for a largish DB in 8.2 vs. 8.3 vs. 8.4

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: "Todd A(dot) Cook" <tcook(at)blackducksoftware(dot)com>
Cc: "pgsql-general(at)postgresql(dot)org" <pgsql-general(at)postgresql(dot)org>
Subject: Re: FYI: Load times for a largish DB in 8.2 vs. 8.3 vs. 8.4
Date: 2009-06-22 16:52:48
Message-ID: 20305.1245689568@sss.pgh.pa.us
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"Todd A. Cook" <tcook(at)blackducksoftware(dot)com> writes:
> Todd A. Cook wrote:
>> Tom Lane wrote:
>>> If you have time to repeat the experiments, it would be interesting to
>>> see what happens with consistent default_statistics_target across 8.3
>>> and 8.4.
>>
>> That would seem to be it:
>> 8.4b2 183 min 84,028,897,040 on (defaults, default_statistics_target=10)
>>
>> I'll run the test on 8.3.7 with default_statistics_target=100 over the weekend.

> The results for this are also consistent with Tom's theory:
> 8.3.7 205 min 84,048,866,924 on (defaults, default_statistics_target=100)

OK, thanks for following up. So this is a different effect from the
COPY ring buffer size issue being argued about over on pgsql-hackers.
I think we can just say that this one is a price being paid
intentionally for better statistics, and if you don't need better
statistics you can back off the target setting ...

regards, tom lane

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