title: efficient and extensible algorithms for multi query optimization. authors: s. sudarshan , siddhesh bhobe , s. seshadri , prasan roy. venue: sigmod conference. year: 2000
title: opt + + : an object-oriented implementation for extensible database query optimization. authors: navin kabra , david j. dewitt. venue: the vldb journal -- the international journal on very large data bases. year: 1999