Presents a novel decomposition algorithm that breaks a multilevel relation into single-level relations and a novel recovery algorithm which reconstructs the original multilevel relation from the decomposed single-level relations. There are several novel aspects to these decomposition and recovery algorithms which provide substantial advantages over previous proposals. The algorithms are formulated in the context of an operational semantics for multilevel relations, defined here by generalizing the usual update operations of structured query language (SQL) to multilevel relations. The algorithms, with minor modifications, can easily accommodate alternative update semantics which have been proposed in the literature. The algorithms are efficient because recovery is based solely on union-like operations without any use of joins. The decomposition is intuitively and theoretically simple, giving a sound basis for correctness.
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