Tim Walker (6/25/2009)
Additionally I am guessing it uses the index based on the varchar(3) column because it occupies less pages than the varchar(15) one.
Depending, of course, on the size of the string stored. If all the strings in the varchar(3) are exactly 3 chars long and all the strings in the varchar(15) are either 2 or 3 characters long, then the index on the varchar(15) will be smaller.
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability