| From: | Alvaro Herrera <alvherre(at)dcc(dot)uchile(dot)cl> |
|---|---|
| To: | Greg Stark <gsstark(at)mit(dot)edu> |
| Cc: | pgsql-general(at)postgresql(dot)org |
| Subject: | Re: Optimizer isn't perfect |
| Date: | 2003-08-31 20:09:41 |
| Message-ID: | 20030831200941.GC30107@dcc.uchile.cl |
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| Thread: | |
| Lists: | pgsql-general |
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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