From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | siracusa(at)mindspring(dot)com |
Cc: | Postgres Patches <pgsql-patches(at)postgresql(dot)org> |
Subject: | Re: [PERFORM] Feature request: smarter use of |
Date: | 2004-03-07 06:28:38 |
Message-ID: | 1337.1078640918@sss.pgh.pa.us |
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Lists: | pgsql-patches |
John Siracusa <siracusa(at)mindspring(dot)com> writes:
> ... Actually, I'm still not sure how you
> can conclude that foo is not null simply by seeing func(..., foo, ...) where
> func() is strict. Do strict functions and operators simply not allow null
> args?
That was what the comments were about ;-). A "strict" operator is one
that always returns NULL if any input is NULL. This does guarantee that
the WHERE condition will fail, but it takes a bit of analysis to see
that the implication is valid.
> Here's hoping that my next performance enhancement suggestion will be
> complex enough that no one will entertain the thought of asking me for a
> patch... ;)
I had quite the opposite motivation in mind in asking you to prototype
this ;-) ...
regards, tom lane
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