COMMON SUBEXPRESSION ISOLATION IN MULTIPLE QUERY OPTIMIZATION

The simultaneous optimization of multiple queries submitted to a database system may lead to substantial savings over the current approach of optimizing each query separately. Isolating common subexpressions in multiple queries and treating their execution as a sharable resource are important prerequisites. This chapter presents techniques for recognizing, supporting, and exploiting common subexpressions in record-oriented, relational algebra, domain relational calculus, and tuple relational calculus query representations. It also investigates preconditions that transaction management mechanisms must satisfy to make multiple query optimization effective.Information Systems Working Papers Serie