We address the problem of deriving lower and upper bounds for the cardinality of the projections of a database relation, given a set of functional dependencies on the relation schema and measures of the cardinalities of the attributes in the schema. It is shown that deciding whether a given number is the least upper bound of a projection cardinality is an NP-complete problem, whereas determining whether the greatest lower bound and the least upper bound coincide can be easily solved in linear time. © 1992.

On the complexity of finding bounds for projection cardinalities in relational databases / Ciaccia P.; Maio D.. - In: INFORMATION SYSTEMS. - ISSN 0306-4379. - STAMPA. - 17:6(1992), pp. 511-515. [10.1016/0306-4379(92)90029-M]

On the complexity of finding bounds for projection cardinalities in relational databases

Ciaccia P.;Maio D.
1992

Abstract

We address the problem of deriving lower and upper bounds for the cardinality of the projections of a database relation, given a set of functional dependencies on the relation schema and measures of the cardinalities of the attributes in the schema. It is shown that deciding whether a given number is the least upper bound of a projection cardinality is an NP-complete problem, whereas determining whether the greatest lower bound and the least upper bound coincide can be easily solved in linear time. © 1992.
1992
On the complexity of finding bounds for projection cardinalities in relational databases / Ciaccia P.; Maio D.. - In: INFORMATION SYSTEMS. - ISSN 0306-4379. - STAMPA. - 17:6(1992), pp. 511-515. [10.1016/0306-4379(92)90029-M]
Ciaccia P.; Maio D.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/918302
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