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.