title: implementation of two semantic query optimization techniques in db2 universal database. authors: k. bernhard schiefer , fred koo , t. y. cliff leung , linqi liu , jarek gryz , xiaoyan qian , qi cheng. venue: vldb. year: 1999.0
title: opt + + : an object-oriented implementation for extensible database query optimization the vldb journal -- the international journal on very large data bases. authors: navin kabra , david j. dewitt. venue: nan. year: 1999.0