A query optimizer analyzes a query and triggers a sequence of transformations to achieve optimal performance for joined table expressions. The transformations include pushing down predicates for joined table expressions and pushing down non-null predicates to simplify join operators for joined table...http://www.google.fr/patents/US6385603?utm_source=gb-gplus-shareBrevet US6385603 - Joined table expression optimization by query transformation
Joined table expression optimization by query transformation
