Operation-Oriented Query Language Approach for
Recursive Queries: Part 1 Functional Definition
Timo Niemi# and Kalervo Järvelin+
#Department of Computer Science
+Department of Information Studies
University of Tampere
P.O.Box 607
FIN-33101 TAMPERE, Finland
Information Systems 17(1), 1992: 49-75.
Abstract
So far the aspects related to efficient processing have dominated the
research on recursive queries. In this paper we consider how the
formulation of recursive queries can be made easier from the view point
of the non-professional user - also in the context of complex recursive
queries. It is obvious that the conventional rule-based way of defining is
too hard and cumbersome for many non-professional users. We provide
operations at a high abstraction level in terms of which the user can
formulate his recursive queries in a compact and convenient way. In our
approach recursive processing is needed for constructing transitive
relationships among data. In practice, it is often very important to compute
transitive relationships among several union-compatible binary relations
instead of one binary relation as usual. We define the operations so that they
are able to manipulate transitive relationships among several relations.
For the changing needs of the user our approach contains three kinds of
operations: relation-oriented, node-oriented and path-oriented operations.
In this paper we specify a functional language consisting of operations of
these types and give several examples on how the user can formulate his
recursive queries in terms of this language. We also discuss its role in
deductive databases, i.e. its integration with processing based on an
extensional database.
Keywords: Deductive databases, recursive queries, transitive relationships,
knowledge representation, functional specification.
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