Abstract
We claim that the representative instance of [Ho1, Va3] is a correct representation of the data stored in a database even when the relations of the database are not the projections of a single universal instance. If no constraint (other than functional and join dependencies) is imposed on the data, then projections of the representative instance cannot always be computed by lossless joins. We show that if the database satisfies a modified foreign-key constraint, then projections of the representative instance can be computed by performing the union of several lossless joins. A class of relation schemes for which no constraint is necessary is characterized, and we show how to compute projections of the representative instance for databases that belong to this class.
Original language | English |
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Title of host publication | Proceedings of the 1981 ACM SIGMOD International Conference on Management of Data, SIGMOD 1981 |
Publisher | Association for Computing Machinery |
Pages | 108-120 |
Number of pages | 13 |
ISBN (Print) | 0897910400 |
DOIs | |
State | Published - 29 Apr 1981 |
Externally published | Yes |
Event | 1981 ACM SIGMOD International Conference on Management of Data, SIGMOD 1981 - Ann Arbor, United States Duration: 29 Apr 1981 → 1 May 1981 |
Publication series
Name | Proceedings of the ACM SIGMOD International Conference on Management of Data |
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ISSN (Print) | 0730-8078 |
Conference
Conference | 1981 ACM SIGMOD International Conference on Management of Data, SIGMOD 1981 |
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Country/Territory | United States |
City | Ann Arbor |
Period | 29/04/81 → 1/05/81 |
Bibliographical note
Publisher Copyright:© 1981 ACM.