Re: Optimizing maximum/minimum queries (yet again)

On Fri, Apr 08, 2005 at 23:40:28 -0400, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Bruno Wolff III <bruno@wolff.to> writes:
> > It should be possible to make this work for bool_and and bool_or as those
> > are equivalent to min and max for the boolean type.
> 
> This would just be a matter of marking them properly in the catalogs.
> 
> However, are they really equivalent in the corner cases?  In particular,
> I think boolean AND across zero input rows is probably supposed to
> return TRUE, not NULL.

I am not sure what the spec says, but according to how the seem to work,
the answer appears to be that they are equivalent.

area=> select bool_and(true) where false;bool_and
----------

(1 row)

area=> select bool_or(true) where false;bool_or
---------

(1 row)