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... --
- Thomas Swan                                   
- Network Administrator
- Graduate Student  - Computer Science
-
- The Institute for Continuing Studies
- The University of Mississippi
-
- http://www.ics.olemiss.edu
- http://www.olemiss.edu