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Re: [PERFORM] Bad n_distinct estimation; hacks suggested?

From: Rod Taylor <rbt(at)sitesell(dot)com>
To: Greg Stark <gsstark(at)mit(dot)edu>
Cc: Gurmeet Manku <manku(at)cs(dot)stanford(dot)edu>,pgsql-hackers(at)postgresql(dot)org
Subject: Re: [PERFORM] Bad n_distinct estimation; hacks suggested?
Date: 2005-04-26 23:10:11
Message-ID: 1114557011.77587.107.camel@home (view raw or flat)
Thread:
Lists: pgsql-hackerspgsql-performance
On Tue, 2005-04-26 at 19:03 -0400, Greg Stark wrote:
> This one looks *really* good. 
> 
>  http://www.aladdin.cs.cmu.edu/papers/pdfs/y2001/dist_sampl.pdf
> 
> It does require a single full table scan 

Ack.. Not by default please.

I have a few large append-only tables (vacuum isn't necessary) which do
need stats rebuilt periodically.

Lets just say that we've been working hard to upgrade to 8.0 primarily
because pg_dump was taking over 18 hours to make a backup.

-- 
Rod Taylor <rbt(at)sitesell(dot)com>


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