1. A computer implemented method for performing a query on a relational database, the method comprising: receiving, by a computer, a query; determining, by the computer, a corresponding complexity class of a plurality of complexity classes for the query; routing, by the computer, the query to a corresponding query processor of a plurality of query processors based on the corresponding complexity class determined for the submitted query; and executing, by the computer, the query on the corresponding query processor according to a determined execution plan.