Definition
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
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.
Bertossi L. Consistent query answering in databases. ACM SIGMOD Rec. 2006;35(2):68–76.
Chomicki J. Consistent query answering: five easy pieces. In: Proceedings of the 11th International Conference on Database Theory; 2007. p. 1–17.
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Bertossi, L. (2018). Consistent Query Answering. In: Liu, L., Özsu, M.T. (eds) Encyclopedia of Database Systems. Springer, New York, NY. https://doi.org/10.1007/978-1-4614-8265-9_5021
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DOI: https://doi.org/10.1007/978-1-4614-8265-9_5021
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