Multiple column indexes

[Garth Keesler <garthk@xxxxxxxxx>]

I have a primary key made up of two varchar(128) columns, typically less 
than 16 chars each. Concatenating the two columns would still be unique. 
Would it make sense to concat the two columns, using a unique separator 
like '~' and index on that single column or would that be more trouble 
than the potential performance gains?

Thanx,
Garth