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Re: Simple postgresql.conf wizard -- Statistics idea...

From: Decibel! <decibel(at)decibel(dot)org>
To: Dann Corbit <DCorbit(at)connx(dot)com>
Cc: <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Simple postgresql.conf wizard -- Statistics idea...
Date: 2008-11-26 19:24:40
Message-ID: B6A275EE-8184-4073-9A0F-5B7A7B7000F9@decibel.org (view raw or flat)
Thread:
Lists: pgsql-hackers
On Nov 25, 2008, at 8:59 PM, Dann Corbit wrote:
> It is a simple matter to calculate lots of interesting univarate  
> summary
> statistics with a single pass over the data (perhaps during a vacuum
> full).


I don't think that the problem we have is how to collect statistics  
(well, except for cross-field stuff); the problem is what to actually  
do with them. What we need people to look at is how we can improve  
query plan estimates across the board. Row count estimates, page  
access estimates, the cost estimates for accessing those pages, etc.  
This isn't a coding problem, it's an algorithm problem. It needs  
someone with an advanced (if not expert) grasp of statistics who can  
come up with better ways of estimating these things.

So, if you have a statistics hammer to wield, I think you'll find a  
lot of nails sticking up in the planner code. Hammer on those before  
worrying about additional stats to collect. :)
-- 
Decibel!, aka Jim C. Nasby, Database Architect  decibel(at)decibel(dot)org
Give your computer some brain candy! www.distributed.net Team #1828



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