The problem of incomplete information in relational databases:
Abstract: "In practice it is often the case that the available information is incomplete with respect to the information that is supposed to be recorded in the database. We consider the problems raised by this situation in the context of the relational model. The basic semantic assumption is th...
Gespeichert in:
| 1. Verfasser: | |
|---|---|
| Format: | Buch |
| Sprache: | English |
| Veröffentlicht: |
1989
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| Schriftenreihe: | Helsingin Yliopisto / Department of Computer Science: Report / A
1989,1. |
| Schlagworte: | |
| Zusammenfassung: | Abstract: "In practice it is often the case that the available information is incomplete with respect to the information that is supposed to be recorded in the database. We consider the problems raised by this situation in the context of the relational model. The basic semantic assumption is that an incomplete database is a set of complete databases (relations). We show that there are two natural lattice structures on the set of all sets of relations. These lattices enable us to give precise meanings to operations performed on incomplete databases. The operations are querying, dependency enforcement and updates. There are several candidate tools for storing and manipulating databases with incomplete information. We focus on generalizations of relations These generalizations, called tables allow variables representing unknown values as entries, as well as entries constraining the variables. We define four increasingly (syntactically) stricter classes of tables and we study their abilities to serve as a basis for implementing incomplete databases and the operations on them. It turns out that the new class of Horn tables is the most significant from a practical point of view. In this class of tables we are able to efficiently evaluate positive existential queries and in some cases least fixpoint (recursive) queries. In Horn tables we can also efficiently incorporate the information contained in one join dependency and a set of equality generating dependencies, as well as hold the result of a subclass of the update operations. |
| Beschreibung: | Helsinki, Univ., Diss. |
| Beschreibung: | IV, 156 S., III Bl. |
| ISBN: | 9514549414 |
Internformat
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| 500 | |a Helsinki, Univ., Diss. | ||
| 520 | 3 | |a Abstract: "In practice it is often the case that the available information is incomplete with respect to the information that is supposed to be recorded in the database. We consider the problems raised by this situation in the context of the relational model. The basic semantic assumption is that an incomplete database is a set of complete databases (relations). We show that there are two natural lattice structures on the set of all sets of relations. These lattices enable us to give precise meanings to operations performed on incomplete databases. The operations are querying, dependency enforcement and updates. There are several candidate tools for storing and manipulating databases with incomplete information. We focus on generalizations of relations | |
| 520 | 3 | |a These generalizations, called tables allow variables representing unknown values as entries, as well as entries constraining the variables. We define four increasingly (syntactically) stricter classes of tables and we study their abilities to serve as a basis for implementing incomplete databases and the operations on them. It turns out that the new class of Horn tables is the most significant from a practical point of view. In this class of tables we are able to efficiently evaluate positive existential queries and in some cases least fixpoint (recursive) queries. In Horn tables we can also efficiently incorporate the information contained in one join dependency and a set of equality generating dependencies, as well as hold the result of a subclass of the update operations. | |
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Datensatz im Suchindex
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| author | Grahne, Gösta |
| author_facet | Grahne, Gösta |
| author_role | aut |
| author_sort | Grahne, Gösta |
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| building | Verbundindex |
| bvnumber | BV007676448 |
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| ctrlnum | (OCoLC)21425179 (DE-599)BVBBV007676448 |
| discipline | Informatik |
| format | Book |
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| genre_facet | Hochschulschrift |
| id | DE-604.BV007676448 |
| illustrated | Not Illustrated |
| indexdate | 2024-07-09T17:07:26Z |
| institution | BVB |
| isbn | 9514549414 |
| language | English |
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| physical | IV, 156 S., III Bl. |
| publishDate | 1989 |
| publishDateSearch | 1989 |
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| series2 | Helsingin Yliopisto / Department of Computer Science: Report / A |
| spelling | Grahne, Gösta Verfasser aut The problem of incomplete information in relational databases 1989 IV, 156 S., III Bl. txt rdacontent n rdamedia nc rdacarrier Helsingin Yliopisto / Department of Computer Science: Report / A 1989,1. Helsinki, Univ., Diss. Abstract: "In practice it is often the case that the available information is incomplete with respect to the information that is supposed to be recorded in the database. We consider the problems raised by this situation in the context of the relational model. The basic semantic assumption is that an incomplete database is a set of complete databases (relations). We show that there are two natural lattice structures on the set of all sets of relations. These lattices enable us to give precise meanings to operations performed on incomplete databases. The operations are querying, dependency enforcement and updates. There are several candidate tools for storing and manipulating databases with incomplete information. We focus on generalizations of relations These generalizations, called tables allow variables representing unknown values as entries, as well as entries constraining the variables. We define four increasingly (syntactically) stricter classes of tables and we study their abilities to serve as a basis for implementing incomplete databases and the operations on them. It turns out that the new class of Horn tables is the most significant from a practical point of view. In this class of tables we are able to efficiently evaluate positive existential queries and in some cases least fixpoint (recursive) queries. In Horn tables we can also efficiently incorporate the information contained in one join dependency and a set of equality generating dependencies, as well as hold the result of a subclass of the update operations. Relational databases Algorithmus (DE-588)4001183-5 gnd rswk-swf Datenverwaltung (DE-588)4011168-4 gnd rswk-swf Relationale Datenbank (DE-588)4049358-1 gnd rswk-swf Relationales Datenbanksystem (DE-588)4130535-8 gnd rswk-swf Unvollkommene Information (DE-588)4140474-9 gnd rswk-swf (DE-588)4113937-9 Hochschulschrift gnd-content Unvollkommene Information (DE-588)4140474-9 s Relationales Datenbanksystem (DE-588)4130535-8 s DE-604 Datenverwaltung (DE-588)4011168-4 s Relationale Datenbank (DE-588)4049358-1 s Algorithmus (DE-588)4001183-5 s 1\p DE-604 Department of Computer Science: Report / A Helsingin Yliopisto 1989,1. (DE-604)BV000904448 1989,1 1\p cgwrk 20201028 DE-101 https://d-nb.info/provenance/plan#cgwrk |
| spellingShingle | Grahne, Gösta The problem of incomplete information in relational databases Relational databases Algorithmus (DE-588)4001183-5 gnd Datenverwaltung (DE-588)4011168-4 gnd Relationale Datenbank (DE-588)4049358-1 gnd Relationales Datenbanksystem (DE-588)4130535-8 gnd Unvollkommene Information (DE-588)4140474-9 gnd |
| subject_GND | (DE-588)4001183-5 (DE-588)4011168-4 (DE-588)4049358-1 (DE-588)4130535-8 (DE-588)4140474-9 (DE-588)4113937-9 |
| title | The problem of incomplete information in relational databases |
| title_auth | The problem of incomplete information in relational databases |
| title_exact_search | The problem of incomplete information in relational databases |
| title_full | The problem of incomplete information in relational databases |
| title_fullStr | The problem of incomplete information in relational databases |
| title_full_unstemmed | The problem of incomplete information in relational databases |
| title_short | The problem of incomplete information in relational databases |
| title_sort | the problem of incomplete information in relational databases |
| topic | Relational databases Algorithmus (DE-588)4001183-5 gnd Datenverwaltung (DE-588)4011168-4 gnd Relationale Datenbank (DE-588)4049358-1 gnd Relationales Datenbanksystem (DE-588)4130535-8 gnd Unvollkommene Information (DE-588)4140474-9 gnd |
| topic_facet | Relational databases Algorithmus Datenverwaltung Relationale Datenbank Relationales Datenbanksystem Unvollkommene Information Hochschulschrift |
| volume_link | (DE-604)BV000904448 |
| work_keys_str_mv | AT grahnegosta theproblemofincompleteinformationinrelationaldatabases |