There is no explicit tuple data type in Perl; you will need to either track both pieces in separate variables or use an array, but note that there are no builtin operators for comparing arrays elementwise: == on arrays compares their lengths (because it imposes scalar context on its operands) and == on array references checks for object identity (true if both references refer to the same object).

However, while the 2-tuple nature of your primary key will not be directly reflected in your program, properly understanding it will help you to maintain clear thinking and accurate reasoning about your code.