A query language for multidimensional arrays: design, implementation, and optimization techniques

  • Authors:

  • Leonid Libkin;Rona Machlin;Limsoon Wong

  • Affiliations:

  • Bell Laboratories, 600 Mountain Avenue, Murray Hill, NJ;Dept. of Comp. & Info. Science, Univ. of Pennsylvania, Philadelphia, PA;Real World Computing Partnership Novel Function Institute of Systems Science Laboratory, Heng Mui Keng Terrace, Singapore 0511

  • Venue:
  • SIGMOD '96 Proceedings of the 1996 ACM SIGMOD international conference on Management of data
  • Year:
  • 1996

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Abstract

While much recent research has focussed on extending databases beyond the traditional relational model, relatively little has been done to develop database tools for querying data organized in (multidimensional) arrays. The scientific computing community has made little use of available database technology. Instead, multidimensional scientific data is typically stored in local files conforming to various data exchange formats and queried via specialized access libraries tied in to general purpose programming languages.To allow such data to be queried using known database techniques, we design and implement a query language for multidimensional arrays. Our main design decision is to treat arrays as functions from index sets to values rather than as collection types. This leads to clean syntax and semantics as well as simple but powerful optimization rules.We present a calculus for arrays that extends standard calculi for complex objects. We derive a higher-level comprehension style query language based on this calculus and describe its implementation, including a data driver for the NetCDF data exchange format. Next, we explore some optimization rules obtained from the equational laws of our core calculus. Finally, we study the expressiveness of our calculus and prove that it essentially corresponds to adding ranking to a query language for complex objects.