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The Computer Journal 1988 31(2):147-154; doi:10.1093/comjnl/31.2.147
© 1988 by British Computer Society
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Fast Implementation of Relational Operations Via Inverse Projections

J. R. Ullmann *

Department of Computer Science, Royal Holloway and Bedford New College, Egham Hill, Egham, Surrey TW20 0EX, UK

A relation can be represented by a bit matrix such that relational intersection, union, natural join, product and equiselection operations can be implemented by parallel bitwise AND and OR of bit matrices. Depending on the dimensions of the bit matrices, this representation is more or less approximate in so far as spurious tuples may be recovered from a bit matrix along with genuine tuples. The process of outputting a result relation is serial and has desirable properties that output tuples can be sorted at no extra cost, and elimination of duplicates from projections actually speeds up the process instead of requiring extra work. Results of small-scale simulation are reported.

Received July 1987. revised August 1987.

* Department of Computer Science, Royal Holloway and Bedford New College, Egham Hill, Egham, Surrey TW20 0EX


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