Re: index vs. seq scan choice?
- From: "Joshua D. Drake" <jd(at)commandprompt(dot)com>
- To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
- Cc: Alvaro Herrera <alvherre(at)commandprompt(dot)com>, George Pavlov <gpavlov(at)mynewplace(dot)com>, pgsql-general(at)postgresql(dot)org
- Subject: Re: index vs. seq scan choice?
- Date: Thu, 24 May 2007 19:57:10 -0700
- Message-id: <46565086(dot)2040705(at)commandprompt(dot)com>
Tom Lane wrote:
Alvaro Herrera <alvherre(at)commandprompt(dot)com> writes:
Tom Lane wrote:
(The default statistics target is 10, which is widely considered too
low --- you might find 100 more suitable.)
Does this mean that we should look into raising the default a bit?
Probably ... the question is to what.
The default of 10 was chosen in our usual spirit of conservatism ---
and IIRC it was replacing code that tracked only *one* most common
value, so it was already a factor of 10 better (and more expensive)
than what was there before. But subsequent history suggests it's
too small. I'm not sure I want to vote for another 10x increase by
default, though.
Outside of longer analyze times, and slightly more space taken up by the
statistics, what is the downside? I mean in reality... what is setting
to 100 going to do to effect actual production usage of even a modest
machine?
Sincerely,
Joshua D. Drake
regards, tom lane
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