On Tue, 22 Jul 2003, Bruce Momjian wrote:
> Well, my 2 cents is that though we consider NULL when ordering via ORDER
> BY, we ignore it in MAX because it really isn't a value, and NaN seems
> to be similar to NULL.
>
> When doing ORDER BY, we have to put the NULL value somewhere, so we put
> it at the end, but with aggregates, we aren't required to put the NULL
> somewhere, so we ignore it. Should that be the same for NaN? I just
> don't see how we can arbitrarly say it is greater/less than other
> values.
But we already do. When doing a less than/greater than comparison, 'NaN'
is considered greater than normal values which is different from NULL
which returns unknown for both.