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)
To avoid OID index retrieval becoming a bottleneck, eecient buuering strategies are needed to minimize the number of disk accesses. In this paper, we develop analytical cost models which we use to nd optimal sizes of the index page buuer and the index entry cache, for diierent memory sizes, index sizes, and access patterns. Because existing buuer hit(More)
As main memory capacity increases, more of the database read requests will be satissed from the buuer system. Consequently, the amount of disk write operations relative to disk read operations will increase. This calls for a focus on write optimized storage managers. In this paper we show how the Vagabond object storage manager uses no-overwrite sequential(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)