BETWEEN patch

A patch to gram.y in src/backend/parser

Provides for the SQL99 expected behavior of
select * from foo where fo_num between 1 and 5
yields the same result as
select * from foo where fo_num between 5 and 1

Granted this is brute force and not very elegant, however it does provide
the correct behavior. Optimally it would be nice to do a comparison on the
values after between and then sort the two limiters and do a single
rewrite leaving only one pass or scan.

In other words in pseudo SQL:

select * from foo where fo_num between a and b

becomes

select * from foo where ((fo_num >= min_value(a, b)) and (fo_num <=
max_value(a,b))

This would yield only two comparisons or resolutions and then a single
sequential or index scan to find the correct tuples.

This was done against beta1...