| From: | Martijn van Oosterhout <kleptog(at)svana(dot)org> |
|---|---|
| To: | Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-hackers(at)postgresql(dot)org, pgsql-performance(at)postgresql(dot)org, Andrea Olson <Aolson(dot)CCAP(dot)Courts(at)wicourts(dot)gov>, Bill Severson <BSEVERS(dot)CCAP(dot)Courts(at)wicourts(dot)gov>, John Hutchins <jhutchi(dot)CCAP(dot)Courts(at)wicourts(dot)gov>, Randy Peterson <RPETERS(dot)CCAP(dot)Courts(at)wicourts(dot)gov>, Shannon Spranger <ssprang(dot)CCAP(dot)Courts(at)wicourts(dot)gov> |
| Subject: | Re: EXISTS optimization |
| Date: | 2007-03-24 13:07:59 |
| Message-ID: | 20070324130759.GA1089@svana.org |
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| Lists: | pgsql-hackers pgsql-performance |
On Fri, Mar 23, 2007 at 05:30:27PM -0500, Kevin Grittner wrote:
> I don't understand -- TRUE OR UNKNOWN evaluates to TRUE, so why would
> the IN need to continue? I'm not quite following the rest; could you
> elaborate or give an example? (Sorry if I'm lagging behind the rest
> of the class here.)
You're right, I'm getting confused with the interaction of NULL and NOT
IN.
The multiple evaluation thing still applies, but that's minor.
Have a nice day,
--
Martijn van Oosterhout <kleptog(at)svana(dot)org> http://svana.org/kleptog/
> From each according to his ability. To each according to his ability to litigate.
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