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<p>Object-oriented database systems (OODBs) have created a demand for relationally complete, extensible, and declarative object-oriented query languages. Until now, the runtime 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. The authors 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 main memory (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. Cost-based optimizations in WS-IRIS using ObjectLog are presented. 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 to be only a necessary condition for better performance. An efficient optimization is of crucial importance as well.</p>
object-oriented database; main memory resident; declarative object-oriented language; typed Datalog; object-oriented query languages; relational engine; magnetic disk resident databases; WS-OSQL; WS-IRIS database; system architecture; data structures; optimization techniques; ObjectLog; typing; overloading; foreign predicates; object-oriented databases; object-oriented languages; query languages; query processing; relational databases

W. Litwin and T. Risch, "Main Memory Orientated Optimization of OO Queries Using Typed Datalog with Foreign Predicates," in IEEE Transactions on Knowledge & Data Engineering, vol. 4, no. , pp. 517-528, 1992.
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