US Patent 7917498 Method and system for dynamic join reordering

A database engine and a system running a database engine utilize a dynamic join reordering feature to change the order of two or more join operations while a query is executing. The database engine starts execution of the query with an initial join order setting but monitors the execution of the query to determine whether the initial join order or some other join order would provide better runtime performance. If another join order would provide better performance, then the database engine can change the join order during query execution and complete the query using the new join order.