From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | Martijn van Oosterhout <kleptog(at)svana(dot)org> |
Cc: | Hiroshi Inoue <Inoue(at)tpf(dot)co(dot)jp>, Mike Mascari <mascarm(at)mascari(dot)com>, pgsql-general(at)postgresql(dot)org |
Subject: | Re: Partial Indices vs. mixing columns and functions |
Date: | 2001-07-17 15:10:13 |
Message-ID: | 24966.995382613@sss.pgh.pa.us |
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Lists: | pgsql-general |
Martijn van Oosterhout <kleptog(at)svana(dot)org> writes:
> I've been think about adding IS (NOT) NULL type clauses and it doesn't look
> too hard but I wonder if my logic is right.
I think all you need is to add the correct implication rules to
indxpath.c. Let's see:
IS NULL => IS NULL
IS NOT NULL => IS NOT NULL
IS TRUE => IS TRUE
IS TRUE => IS NOT FALSE (but not vice versa)
IS TRUE => IS NOT UNKNOWN (but not vice versa)
IS NOT TRUE => IS NOT TRUE
and similarly to the last four for IS FALSE and IS UNKNOWN. No?
BTW, it might be a good idea to split out the implication code into a
new file, probably in optimizer/prep or optimizer/utils, rather than
letting it continue to grow where it is. Doesn't seem like it belongs
in indxpath.c.
regards, tom lane
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