"Ross J. Reedstrom" <reedstrm@rice.edu> writes:
>>>> or add another ordering operator that is only used for the sort case
>>>> (use of '>' and '<' seems to be hardcoded all the way to the parser)
>>
>> don't even think about that...
> Sure, but any ideas _how_ to get 'NaN > +Infinity' to happen only during a
> sort operation, and not when '>' is called explicity as a WHERE condition,
> by touching only type specific code?
That's exactly what you shouldn't even think about. The entire index
and sorting system is predicated on the assumption that '<' and related
operators agree with the order induced by a btree index. You do not get
to make the operators behave differently in the free-standing case than
when they are used with an index.
> 'Cause I'd call it a bug to be able to say:
> SELECT * from foo where f8 > 'Infinity';
> and get anything at all back.
I agree it's pretty arbitrary to define NaN as > Infinity, but the sort
ordering is necessarily arbitrary. We can special-case NULL because
that's a type-independent concept, but special-casing NaN is out of the
question IMHO. Pick where you want it in the type-specific order, and
live with it.
regards, tom lane