OPTIMIZATION OF "ASSOCIATE-SELECT" COMPOUND OPERATION IN OBJECT-ORIENTED; DATABASE SYSTEMS
WU Shengli(Institute of Sofware The Chinese Academp of Sciences Beijing 100080)WANG Nengbin(Department of Computer Science and Engineering Southeast University Nanjing 210096)
Associate-Select" compound operation, which is similar in functionality tojoin operation of multi-nested relations in nested relational databases, is a key issue ofquery optimization in object-oriented database systems. This paper proves that the opti-mum solution for treelike "Associate-Select" queries with some restrictions can be obtainedwith polynomial complexity, then presents some algorithrns to deal with the situationwhen birelationship exists in complex objects(for example by defining inverse attribute etal. ). A simulation experiment is performed to demonstrate the steadiness and effectivenes s of the algorithms proposed in the paper.