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Re: BUG #4949: NOT IN is prohibitive slower than the rewrite for medium to large sets

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: "Ole Tange" <postgresql(dot)org(at)tange(dot)dk>
Cc: pgsql-bugs(at)postgresql(dot)org
Subject: Re: BUG #4949: NOT IN is prohibitive slower than the rewrite for medium to large sets
Date: 2009-07-28 13:47:47
Message-ID: 16400.1248788867@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-bugs
"Ole Tange" <postgresql(dot)org(at)tange(dot)dk> writes:
> (modulo NULLs which seem to always cause problems in NOT INs).

> Because it can be rewritten, NOT IN should never be much slower than the
> rewritten solution, as PostgreSQL should simply rewrite NOT IN to the
> above.

Let's see, you understand that the rewrite violates the SQL standard
semantics of NOT IN, but you think we should do it anyway?

			regards, tom lane

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