An optimization technique that reorders outerjoins and antijoins with inner joins in a bottom-up optimizer of a relational database management system (RDBMS)....http://www.google.fr/patents/US6665663?utm_source=gb-gplus-shareBrevet US6665663 - Outerjoin and antijoin reordering using extended eligibility lists
Outerjoin and antijoin reordering using extended eligibility lists