Communication overhead of nested loop operation in multidatabase system

This paper summarizes some of the results from a previous paper by the author (see DTD Technical Memo HPL-DTD-91-5, HP Labs., 1991). The purpose is to characterize the interprocess communication (IPC) overhead in the context of multidatabase operations. A quantitative analysis of the cost of a distributed query is becoming increasingly important as operations across multiple databases are becoming more common. A global nested-loop (NL) join method is one of the least-complicated methods for joining data across data sources. One of the advantages of the algorithm is that it works even when an external operation is a method call whose input parameters, unlike a query, must be bound at invocation time