Abstract: Database query,revision and maintenance are the basic functions of the PROLOG DBMS system.An optimization technique,such as inter clause optimization,is the key to make the system practical.When a database revision operation is executed,the source database and the cache database produced for optimization will probably be inconsistent.The logical relationship between the revision data and the history query is analyzed and the constraint conditions are pointed out in the paper.Some effective database maintenance strategies for a single user are also discussed.