Re: index vs. seq scan choice?

From: "Joshua D(dot) 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: 2007-05-25 02:57:10
Message-ID: 46565086.2040705@commandprompt.com
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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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