From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
Cc: | Christopher Kings-Lynne <chriskl(at)familyhealth(dot)com(dot)au>, pgsql-patches(at)postgresql(dot)org |
Subject: | Re: BETWEEN Help |
Date: | 2002-04-15 00:01:58 |
Message-ID: | 24586.1018828918@sss.pgh.pa.us |
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Lists: | pgsql-patches |
Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> Tom Lane wrote:
>> Yup, that's one place that will need to be taught about it.
> That was actually a reason I was wondering if it was worth changing our
> current BETWEEN code. The optimizer already is complicated and trying
> to do BETWEEN rather than the more simpler statements didn't seem like a
> win.
Actually, an explicit representation of BETWEEN will *help* the
optimizer; right now it has to try to recognize range restrictions
by matching up '>' and '<' clauses. That's a mess already, and I
had no intention of trying to extend that logic to recognize the
clause structures that BETWEEN SYMMETRIC would put out if it weren't
a primitive node type. But if it's a node then recognizing it is
a no-brainer. See clausesel.c.
regards, tom lane
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