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Re: Thoughts on statistics for continuously advancing columns

From: Simon Riggs <simon(at)2ndQuadrant(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Peter Eisentraut <peter_e(at)gmx(dot)net>, Josh Berkus <josh(at)agliodbs(dot)com>, pgsql-hackers(at)postgresql(dot)org, Nathan Boley <npboley(at)gmail(dot)com>
Subject: Re: Thoughts on statistics for continuously advancing columns
Date: 2009-12-31 21:29:48
Message-ID: 1262294988.19367.12311.camel@ebony (view raw or flat)
Thread:
Lists: pgsql-hackers
On Thu, 2009-12-31 at 15:18 -0500, Tom Lane wrote:
> Simon Riggs <simon(at)2ndQuadrant(dot)com> writes:
> > Why not get both max() and min(), then rebase the histogram according to
> > those values. That way the histogram can still move significantly and
> > the technique will still work.
> 
> Define "rebase", keeping in mind that this has to work on datatypes that
> we don't have a distance metric for.

Make it work differently according to whether we have, or not, just as
we do elsewhere with stats. No point in limiting ourselves to the lowest
common denominator, especially when the common case is integer keys and
time datatypes.

-- 
 Simon Riggs           www.2ndQuadrant.com


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