Functional-join processing

  • Authors:

  • R. Braumandl;J. Claussen;A. Kemper;D. Kossmann

  • Affiliations:

  • Universitä/t Passau, Lehrstuhl fü/r Informatik, 94030 Passau, Germany/ e-mail: {braumandl,claussen,kemper,kossmann}@db.fmi.uni-passau.de;Universitä/t Passau, Lehrstuhl fü/r Informatik, 94030 Passau, Germany/ e-mail: {braumandl,claussen,kemper,kossmann}@db.fmi.uni-passau.de;Universitä/t Passau, Lehrstuhl fü/r Informatik, 94030 Passau, Germany/ e-mail: {braumandl,claussen,kemper,kossmann}@db.fmi.uni-passau.de;Universitä/t Passau, Lehrstuhl fü/r Informatik, 94030 Passau, Germany/ e-mail: {braumandl,claussen,kemper,kossmann}@db.fmi.uni-passau.de

  • Venue:
  • The VLDB Journal — The International Journal on Very Large Data Bases
  • Year:
  • 2000

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Abstract

Inter-object references are one of the key concepts of object-relational and object-oriented database systems. In this work, we investigate alternative techniques to implement inter-object references and make the best use of them in query processing, i.e., in evaluating functional joins. We will give a comprehensive overview and performance evaluation of all known techniques for simple (single-valued) as well as multi-valued functional joins. Furthermore, we will describe special order-preserving\/ functional-join techniques that are particularly attractive for decision support queries that require ordered results. While most of the presentation of this paper is focused on object-relational and object-oriented database systems, some of the results can also be applied to plain relational databases because index nested-loop joins\/ along key/foreign-key relationships, as they are frequently found in relational databases, are just one particular way to execute a functional join.