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A Framework for the Investigation of Aggregate Functions in Database Queries

  • Luca Cabibbo
  • Riccardo Torlone
Conference paper
First Online:
Part of the Lecture Notes in Computer Science book series (LNCS, volume 1540)

Abstract

In this paper we present a new approach for studying aggregations in the context of database query languages. Starting from a broad definition of aggregate function, we address our investigation from two different perspectives. We first propose a declarative notion of uniform aggregate function that refers to a family of scalar functions uniformly constructed over a vocabulary of basic operators by a bounded Turing Machine. This notion yields an effective tool to study the effect of the embedding of a class of built-in aggregate functions in a query language. All the aggregate functions most used in practice are included in this classification. We then present an operational notion of aggregate function, by considering a high-order folding constructor, based on structural recursion, devoted to compute numeric aggregations over complex values. We show that numeric folding over a given vocabulary is sometimes not able to compute, by itself, the whole class of uniform aggregate function over the same vocabulary. It turns out however that this limitation can be partially remedied by the restructuring capabilities of a query language.

Keywords

Scalar Function Turing Machine Query Language Expressive Power Relational Algebra 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.
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Copyright information

© Springer-Verlag Berlin Heidelberg 1999

Authors and Affiliations

  • Luca Cabibbo
    • 1
  • Riccardo Torlone
    • 1
  1. 1.Dipartimento di Informatica e AutomazioneUniversità di Roma Tre Via della Vasca NavaleRomaItaly

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