Douglas W. Cornell

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In a relational database environment, transaction response time is likely to be affected by the time required to read the necessary data from secondary storage (disk). In cases where segment scans are used to a significant extent, vertical partitioning of the relation can result in a decrease in the number of disk accesses. The issue is how to set up the(More)
The performance of multiple systems sharing a common data base is analyzed for an architecture with concurrency control using a centralized lock engine. The workload is based on traces from large mainframe systems running IBM's IMS database management system. Based on IMS lock traces the lock contention probability and data base buffer invalidation effect(More)
In a multisystem database system with a function request shipping approach, the databases are partitioned among the multiple systems and a facility is provided to support the shipping of database requests among the systems. This is in contrast to a data sharing multisystem approach in which all systems have direct access to the shared database. The(More)
In a multi-query environment, the marginal utilities of allocating additional buffer to the various queries can be vastly different. The conventional approach examines each query in isolation to determine the optimal access plan and the corresponding locality set. This can lead to performance that is far from optimal. As each query can have different access(More)
Multiple systems coupling incurs performance degradation due to inter-system (global) lock conlention and database buffer invali-dation. At high transaction rates, the level of inter-syslem interference can have a severe hnpact on performance. In this paper, we propose a scheme for transaction routing lhat reduces inter-system interference while keeping(More)