QUERY OPTIMIZATION AND EXECUTION PLAN GENERATION IN OBJECT-ORIENTED DATA MANAGEMENT-SYSTEMS

The generation of execution plans for object-oriented database queries is a new and challenging area of study, Unlike the relational algebra, a common set of object algebra operators has not been defined, Similarly, a standardized object manager interface analogous to storage manager interfaces of relational subsystems does not exist. We define the interface to an object manager whose operations are the executable elements of query execution plans, Parameters to the object manager interface are streams of tuples of object identifiers. The object manager can apply methods and simple predicates to the objects identified in a tuple. Two algorithms for generating such execution plans for queries expressed in an object algebra are presented. The first algorithm runs quickly but may produce inefficient plans, The second algorithm enumerates all possible execution plans and presents them in an efficient, compact representation.