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Answering queries on embedded-complete database schemes

Authors:

Edward P. F. Chan,

Alberto O. MendelzonAuthors Info & Claims

Journal of the ACM (JACM), Volume 34, Issue 2

Pages 349 - 375

https://doi.org/10.1145/23005.23007

Published: 01 April 1987 Publication History

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Abstract

It has been observed that, for some database schemes, users may have difficulties retrieving correct information, even for simple queries. The problem occurs when some implicit “piece” of information, defined on some subset of a relation scheme, is not explicitly represented in the database state. In this situation, users may be required to know how the state and the constraints interact before they can retrieve the information correctly.

In this paper, the formal notion of embedded-completeness is proposed, and it is shown that schemes with this property avoid the problem described above. A polynomial-time algorithm is given to test whether a database scheme is independent and embedded-complete. Under the assumption of independence, it is shown that embedded-complete schemes allow efficient computation of optimal relational algebra expressions equivalent to the X-total projection, for any set of attributes X.

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Cited By

View all

Torlone RAtzeni P(1999)Efficient Database Updates with Independent SchemesSIAM Journal on Computing10.1137/S009753979325799X28:3(1112-1135)Online publication date: 21-Feb-1999
https://dl.acm.org/doi/10.1137/S009753979325799X
Hernández HWang K(1993)On the boundedness of constant-time-maintainable database schemesSIAM Journal on Computing10.1137/022200322:1(29-45)Online publication date: 1-Feb-1993
https://dl.acm.org/doi/10.1137/0222003
Atzeni PTorlone R(1992)Updating relational databases through weak instance interfacesACM Transactions on Database Systems10.1145/146931.14693617:4(718-745)Online publication date: 1-Dec-1992
https://dl.acm.org/doi/10.1145/146931.146936
Show More Cited By

Index Terms

Answering queries on embedded-complete database schemes
1. Information systems
  1. Data management systems
    1. Database design and models
      1. Data model extensions
      2. Relational database model
    2. Query languages
      1. Relational database query languages

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Reviews

Reviewer: Robert J. Tufts

One of the least-known problems of relational systems as that some database schemes require the user to know implied relational dependencies and logical connections in order to retrieve the correct data. This paper proposes a definition of embedded-complete relational schemes that do not have this undesirable property. It begins by summarizing the basic theory and definitions of relational systems as published in the last few years. This is followed by a discussion of the embedded-complete and independent schemes. The authors then present a polynomial-time algorithm to test for embedded-complete relations and conclude that additional study is needed to find an algorithm for testing embedded completeness for connection-trap-free relations. The main purpose of the paper is to extend relational theory to include embedded-complete relations. A secondary purpose appears to be to support the creation of automatic connections between relations, which would be needed by a universal relation interface system. (Such a system would shield the user from specifying logical connections among relations.) Both purposes are satisfied by the paper, though how automatic connections would be done on even embedded-complete relational schemes is not covered. The strength of this paper is in its rigor and readability. The examples given are useful in showing why embedded completeness is necessary even for simple queries on just a few relations. The length is about right for the material covered and the subject is well presented. Researchers into relational theory and those developing relational database management system utilities will be most interested in this paper. However, database administrators will probably not be interested, as most operational systems now allow the administrator to specify relational views for the user that will avoid the described problem. A good bibliography is included, though one-third of the papers cited were written in conjunction with the authors of this paper.

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Published In

Journal of the ACM Volume 34, Issue 2

April 1987

286 pages

ISSN:0004-5411

EISSN:1557-735X

DOI:10.1145/23005

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Publisher

Association for Computing Machinery

New York, NY, United States

Publication History

Published: 01 April 1987

Published in JACM Volume 34, Issue 2

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Torlone RAtzeni P(1999)Efficient Database Updates with Independent SchemesSIAM Journal on Computing10.1137/S009753979325799X28:3(1112-1135)Online publication date: 21-Feb-1999
https://dl.acm.org/doi/10.1137/S009753979325799X
Hernández HWang K(1993)On the boundedness of constant-time-maintainable database schemesSIAM Journal on Computing10.1137/022200322:1(29-45)Online publication date: 1-Feb-1993
https://dl.acm.org/doi/10.1137/0222003
Atzeni PTorlone R(1992)Updating relational databases through weak instance interfacesACM Transactions on Database Systems10.1145/146931.14693617:4(718-745)Online publication date: 1-Dec-1992
https://dl.acm.org/doi/10.1145/146931.146936
Chan EArzeni P(1992)Connection-trap-free database schemesJournal of Computer and System Sciences10.1016/0022-0000(92)90001-Y44:1(1-22)Online publication date: 1-Feb-1992
https://dl.acm.org/doi/10.1016/0022-0000%2892%2990001-Y
Hernández HChan E(1991)Constant-time-maintainable BCNF database schemesACM Transactions on Database Systems10.1145/115302.11530116:4(571-599)Online publication date: 1-Dec-1991
https://dl.acm.org/doi/10.1145/115302.115301
Chan EHernández H(1991)Independence-reducible database schemesJournal of the ACM10.1145/115234.11536238:4(854-886)Online publication date: 1-Oct-1991
https://dl.acm.org/doi/10.1145/115234.115362
Atzeni PChan E(1991)Independent database schemes under functional and inclusion dependenciesActa Informatica10.1007/BF0126165628:8(777-799)Online publication date: 1-Aug-1991
https://dl.acm.org/doi/10.1007/BF01261656
KANELLAKIS P(1990)Elements of Relational Database TheoryFormal Models and Semantics10.1016/B978-0-444-88074-1.50022-6(1073-1156)Online publication date: 1990
https://doi.org/10.1016/B978-0-444-88074-1.50022-6
Leymann F(1990)UDH: a universal relation systemData & Knowledge Engineering10.1016/0169-023X(90)90031-85:1(21-38)Online publication date: 1-Mar-1990
https://dl.acm.org/doi/10.1016/0169-023X%2890%2990031-8
Atzeni Pde Bernardis M(1990)A new interpretation for Null values in the weak instance modelJournal of Computer and System Sciences10.1016/0022-0000(90)90032-G41:1(25-43)Online publication date: 1-Aug-1990
https://dl.acm.org/doi/10.1016/0022-0000%2890%2990032-G
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Answering imprecise database queries: a novel approach

Answering Queries Using Views

Answering Queries Using Views

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