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List:       postgresql-general
Subject:    Re: [GENERAL] Optimizer isn't perfect
From:       Alvaro Herrera <alvherre () dcc ! uchile ! cl>
Date:       2003-08-31 20:09:41
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On Fri, Aug 29, 2003 at 10:37:32AM -0400, Greg Stark wrote:

> Except if it guesses wrong by assuming it isn't selective it would be maybe
> 50% slower doing lots of index lookups instead of a more efficient full table
> scan and join. If it guesses wrong by assuming it'll be very selective as it
> is in this case then it's 1000% slower doing repeated full table scans.

Well, there are operators that need some work.  I am seeing less than
ideal behaviour with OVERLAPS, but I think it isn't even documented...

-- 
Alvaro Herrera (<alvherre[a]dcc.uchile.cl>)
"In a specialized industrial society, it would be a disaster
to have kids running around loose." (Paul Graham)

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