| From: | Decibel! <decibel(at)decibel(dot)org> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | "Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov>, "Simon Riggs" <simon(at)2ndquadrant(dot)com>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: IN vs EXISTS equivalence |
| Date: | 2008-08-11 15:19:21 |
| Message-ID: | DD52A3AC-9ED8-47F4-89D8-9D70A8B2DB87@decibel.org |
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| Lists: | pgsql-hackers |
On Aug 8, 2008, at 3:23 PM, Tom Lane wrote:
> * has no set operations (UNION etc), grouping, set-returning functions
> in the SELECT list, LIMIT, or a few other funny cases
Couldn't union/union all be treated as
EXISTS(a)
OR EXISTS(b)
...
Or am I missing some detail with NULLS?
Personally, I'd rather write it as separate EXISTS clauses rather
than using UNION, but perhaps others have a different preference...
--
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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