OPTIMIZING DATABASE QUERY PERFORMANCE BY DERIVING QUERY PREDICATES

摘要

Database Management Systems (DBMS) manage data stored in tables and proce ss database queries against that stored data. The database queries typically specify search conditions (that is, 'predicates') for qualifying database search results to be output by the DBMS. When a database table definition or query includes a given predicate having an expression that operates on a column of a table, it is useful to know whether the expression is monotonic. If the expression is determined to be monotonic, the present invention provides operations for deriving a new predicate from the given predicate for use in a new database query. Advantageously, the use of a new or derived predicate improves operational efficiency of the DBM S. Operation is provided for detecting a type of monotonicity related to the expression, and uses the detected type of monotonicity for generating the derived predicate.