Text size
  • Small
  • Medium
  • Large
Contrast
  • Standard
  • Blue text on blue
  • High contrast (Yellow text on black)
  • Blue text on beige

    Observational Distinguishability of Databases with Object Identity

    Database Programming Languages

    Italy. 6th - 8th September 1995

    AUTHORS

    A.S. Kosky

    ABSTRACT

    We will examine the problem of distinguishing between database instances and values in models which incorporate object-identities and recursive data-structures.

    We will show that the notion of observational distinguishability is intricately linked to the languages available for querying a database.

    In particular we will show that, given a simple query language incorporating a test for equality of object-identities, database instances are indistinguishable if they are isomorphic, and that, in a language without any operators on object-identities, database instances are indistinguishable if a bisimilarity relation holds between them.

    Further, such a bisimulation relation may be computed on values, but doing so requires the ability to recurse over all the object-identities in an instance.

    We will then show that systems of keys give rise to observational distinguishability relations which lie between these two extremes.

    We show that a system of keys satisfying certain restrictions provides us with an efficient means of comparing values, while avoiding the need to compare object identities directly.

    PAPER FORMATS

    PDF filePDF Version of this Paper (258kb)