Converting nested algebra expressions into flat algebra expressions

J. Paredaens, D. Van Gucht

Onderzoeksoutput: Bijdrage aan tijdschriftTijdschriftartikelAcademicpeer review

47 Citaten (Scopus)


Nested relations generalize ordinary flat relations by allowing tuple values to be either atomic or set valued. The nested algebra is a generalization of the flat relational algebra to manipulate nested relations. In this paper we study the expressive power of the nested algebra relative to its operation on flat relational databases. We show that the flat relational algebra is rich enough to extract the same "flat information" from a flat database as the nested algebra does. Theoretically, this result implies that recursive queries such as the transitive closure of a binary relation cannot be expressed in the nested algebra. Practically, this result is relevant to (flat) relational query optimization.
Originele taal-2Engels
Pagina's (van-tot)65-93
Aantal pagina's29
TijdschriftACM Transactions on Database Systems
Nummer van het tijdschrift1
StatusGepubliceerd - 1992

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