Data structure for matching attributes?

I need a data structure and data storage solution that is optimal for the following scenario:

Storing: >20M sets of attributes. Each set is of variable length. None are empty.
Matching: An inputted set with all the other stored sets. Comparing and contrasting attributes. Returning the most favorable matched sets.

I don't know where to start.

Start there:

http://www.ibm.com/
http://www.oracle.com/
http://www.sap.com/