Encyclopedia of Database Systems

2018 Edition
| Editors: Ling Liu, M. Tamer Özsu

Consistent Query Answering

  • Leopoldo BertossiEmail author
Reference work entry
DOI: https://doi.org/10.1007/978-1-4614-8265-9_5021


Consistent query answering (CQA) is the problem of querying a database that is inconsistent, i.e., that fails to satisfy certain integrity constraints, in such a way that the answers returned by the database are consistent with those integrity constraints. This problem involves a characterization of the semantically correct or consistent answers to queries in an inconsistent database.

Key Points

Databases may be inconsistent in the sense that certain desirable integrity constraints (ICs) are not satisfied. However, it may be necessary to still use the database, because it contains useful information, and, most likely, most of the data is still consistent, in some sense. CQA, as introduced in [1], deals with two problems. First, with the logical characterization of the portions of data that are consistent in the inconsistent database. Secondly, with developing computational mechanisms for retrieving the consistent data. In particular, when queries are posed to the database,...

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Recommended Reading

  1. 1.
    Arenas M, Bertossi L, Chomicki J. Consistent query answers in inconsistent databases. In: Proceedings of the 18th ACM SIGACT-SIGMOD-SIGART Symposium on Principles of Database Systems; 1999. p. 68–79.Google Scholar
  2. 2.
    Bertossi L. Consistent query answering in databases. ACM SIGMOD Rec. 2006;35(2):68–76.CrossRefGoogle Scholar
  3. 3.
    Chomicki J. Consistent query answering: five easy pieces. In: Proceedings of the 11th International Conference on Database Theory; 2007. p. 1–17.Google Scholar

Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Carleton UniversityOttawaCanada