Re: [HACKERS] Hypothetical suggestions for planner, indexing improvement

On Tue, May 06, 2003 at 09:45:07AM -0400, Tom Lane wrote:
> "Jim C. Nasby" <jim@nasby.net> writes:
> > It would be nice to add support for multi-column IN..
> > WHERE (a, b, c) IN (SELECT a, b, c ...)
>
> RTFM...

As someone pointed out, the documentation says you can't. In this case
the docs are wrong (I've added a note).

> > BTW, does postgresql handle IN and EXISTS differently?
>
> Yes.
>
> > Theoretically if the optimizer was good enough you could transform one
> > to the other and not worry about it.
>
> No.  They have different responses to NULLs in the subselect result.

They appear to operate the same... what's different?
--
Jim C. Nasby (aka Decibel!)                    jim@nasby.net
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