Re: Revisiting default_statistics_target - Mailing list pgsql-hackers

From Stephen Frost
Subject Re: Revisiting default_statistics_target
Date
Msg-id 20090522173532.GJ8123@tamriel.snowman.net
Whole thread Raw
In response to Re: Revisiting default_statistics_target  ("Greg Sabino Mullane" <greg@turnstep.com>)
Responses Re: Revisiting default_statistics_target  ("Joshua D. Drake" <jd@commandprompt.com>)
List pgsql-hackers
Greg,

* Greg Sabino Mullane (greg@turnstep.com) wrote:
> > While most cases were dead even or a modest improvement, his dbt-2 results
> > suggest a 15-20% regression in 8.4.  Changing the default_statistics_taget
> > to 100 was responsible for about 80% of that regression.
> ...
> > The situation where the stats target being so low hurts things the most
> > are the data warehouse use cases.
>
> Er...so why should we change our defaults to support data warehousing
> users? Certainly the rest of the postgresql.conf settings don't attempt
> to do that.

dbt-2 is for OLTP, not for DW.  Greg Smith's comment was actually that
we shouldn't penalize the OLTP crowd (by raising the value) for the
benefit of the DW crowd (who need it higher than 100 anyway).

http://osdldbt.sourceforge.net/
Stephen

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