Polymorphic type inference for the relational algebra
<|reference_start|>Polymorphic type inference for the relational algebra: 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.<|reference_end|>
@article{bussche2001polymorphic,
    title={Polymorphic type inference for the relational algebra},
    author={Jan Van den Bussche, Emmanuel Waller},
    journal={arXiv preprint arXiv:cs/0106035},
    year={2001},
    archivePrefix={arXiv},
    eprint={cs/0106035},
    primaryClass={cs.LO cs.DB}
}