Kjell Bratbergsengen

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In object-oriented database systems (OODB) with logical OIDs, an OID index (OIDX) is needed to map from OID to the physical location of the object. In a transaction time temporal OODB, the OIDX should also index the object versions. In this case, the index entries, which w e c a l l object descriptors (OD), also include the commit timestamp of the(More)
1 Abstract Relational algebra is the instruction set of relational database systems. In this paper, a set of relational algebra operations are described and slightly enhanced for improved efficiency. How these routines can be implemented on a parallel database computer is described in detail. Four operations are handled: projection, join, aggregation and(More)
Simulating distributed database systems is inherently difficult, as there are many factors that may influence the results. This includes architectural options as well as workload and data distribution. In this paper we present the DBsim simulator and some simulation results. The DBsim simulator architecture is extendible, and it is easy to change parameters(More)
In a data base computer consisting of cells with processing capability, the desired goal is to achieve an execution time - for each data base operation - to be inversely proportional to the number of cells. Using rings as a basic building block, we have constructed different intercell communication networks. The capacity of the communication network have(More)