Functional dependencies in Horn clause queries
- 1 March 1991
- journal article
- Published by Association for Computing Machinery (ACM) in ACM Transactions on Database Systems
- Vol. 16 (1) , 31-55
- https://doi.org/10.1145/103140.103142
Abstract
When a database query is expressed as a set of Horn clauses whose execution is by top-down resolution of goals, there is a need to improve the backtracking behavior of the interpreter. Rather than putting on the programmer the onus of using extra-logical operators such as cut to improve performance, we show that some uses of the cut can be automated by inferring them from functional dependencies. This requires some knowledge of which variables are guaranteed to be bound at query execution time; we give a method for deriving such information using data flow analysis.Keywords
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