Litwin, W. and Risch, T. (1992). Main Memory Oriented Optimization of OO Queries using Typed Datalog with Foreign Predicates. Technical Report LiTH-IDA-R-92-24, Department of Computer and Information Science, Linköping University, Sweden. Accepted for publication in IEEE Transactions on Knowledge and Data Engineering and accepted to IEEE Transactions on Knowledge and Data Engineering in a special section on main memory databases. (bibtex),
Abstract: Object-oriented DBMSs (OODBs) have created a demand for relationally complete, extensible, and declarative object-oriented (OO) query languages. Until now, run time performance of such languages was far behind that of procedural OO interfaces. One reason is the internal use of a relational engine with magnetic disk resident databases. We address the processing of the declarative OO language WS-OSQL, provided by the fully operational prototype OODB called WS-IRIS. A WS-IRIS database is MM resident. The system architecture, data structures, and optimization techniques are designed accordingly. WS-OSQL queries are compiled into an OO extension of Datalog called ObjectLog, providing for objects, typing, overloading, and foreign predicates for extensibility. We present cost based optimizations in WS-IRIS using ObjectLog. Performance tests show that WS-IRIS is about as fast as current OODBs with procedural interfaces only and is much faster than known relationally complete systems. These results would not be possible for a traditional disk based implementation. However, MM residency of a database appears only a necessary condition for better performance. An efficient optimization proves of crucial importance as well.
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