Abstract
The representative instance is proposed as a representation of the data stored in a database whose relations are not the projections of a universal instance. Database schemes are characterized for which local consistency implies global consistency. (Local consistency means that each relation satisfies its own functional dependencies; global consistency means that the representative instance satisfies all the functional dependencies.) A method of efficiently computing projections of the representative instance is given, provided that local consistency implies global consistency. Throughout, it is assumed that a cover of the functional dependencies is embodied in the database scheme in the form of keys.
Original language | English |
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Pages (from-to) | 266-286 |
Number of pages | 21 |
Journal | ACM Transactions on Database Systems |
Volume | 8 |
Issue number | 2 |
DOIs | |
State | Published - 1 Jun 1983 |
Externally published | Yes |
Keywords
- Chase
- extension join
- functional dependency
- null value
- relational algebra
- relational database
- representative instance
- universal relation scheme