SYSTEM/U: a database system based on the universal relation assumption
ACM Transactions on Database Systems (TODS)
An introduction to database systems: vol. I (4th ed.)
An introduction to database systems: vol. I (4th ed.)
On the foundations of the universal relation model
ACM Transactions on Database Systems (TODS)
Consequences of assuming a universal relation
ACM Transactions on Database Systems (TODS)
A simplied universal relation assumption and its properties
ACM Transactions on Database Systems (TODS)
Maximal objects and the semantics of universal relation databases
ACM Transactions on Database Systems (TODS)
The theory of joins in relational databases
ACM Transactions on Database Systems (TODS)
Construction of relations in relational databases
ACM Transactions on Database Systems (TODS)
Synthesizing third normal form relations from functional dependencies
ACM Transactions on Database Systems (TODS)
Testing satisfaction of functional dependencies
Journal of the ACM (JACM)
Principles of Database Systems
Principles of Database Systems
SIGMOD '83 Proceedings of the 1983 ACM SIGMOD international conference on Management of data
Toward logical data independence: a relational query language without relations
SIGMOD '82 Proceedings of the 1982 ACM SIGMOD international conference on Management of data
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The two proposed advantages of the universal relation model are that it can deal with the logical navigation problem and the database structure upgrading problem [Maier 1984]. Most previous research has concentrated on the first advantage, to relieve the end-user from logical navigation through the underlying structures. However, the second proposed advantage, database structure upgrading, has not been fully discussed. This is the topic of this paper. An Upgradable Universal Relational System (U2RS), which is able to deal with the database structure upgrading problem, is presented. The procedures for verifying and executing database system upgrading operations are described, various anticipated situations when upgrading an existing universal relation database system are classified, and conditions for determining whether a given system will be upgradable for a given upgrading operation are examined.