1. A computer-implemented method, comprising: modifying a received query, the received query including a first predicate specifying a comparison operator and a second predicate specifying an IS NULL operator, wherein modifying the received query comprises: replacing the comparison operator of the first predicate with an extended comparison operator; and removing the IS NULL operator from the received query, wherein the extended comparison operator is configured to support searching of NULL values in a database management system (DBMS), wherein the extended comparison operator is configured to return rows having column data matching a value predefined to represent NULL values.