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Polymorphic type inference for the relational algebra

Jan Van den Bussche·Emmanuel Waller
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Abstract

We give a polymorphic account of the relational algebra. We introduce a formalism of ``type formulas'' specifically tuned for relational algebra expressions, and present an algorithm that computes the ``principal'' type for a given expression. The principal type of an expression is a formula that specifies, in a clear and concise manner, all assignments of types (sets of attributes) to relation names, under which a given relational algebra expression is well-typed, as well as the output type that expression will have under each of these assignments. Topics discussed include complexity and polymorphic expressive power.

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Jan Van den Bussche, Emmanuel Waller. 2001-06-14. Polymorphic type inference for the relational algebra. https://arxiv.org/abs/cs/0106035

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