A Multi-Set Extended Relational Algebra - A Formal Approach to a Practical Issue

The relational data model is based on sets of tuples, i.e. it does not allow duplicate tuples in a relation. Many database languages and systems do require multi-set place, the high costs of duplicateremoval in database operations is often prohibitive for the use of a data model that does not duplicates. semantics though, either becawe offunctional requirements or because of the high costs of duplicate removal in database operations. Several proposals have been presented that discuss multi-set semantics. As these proposals tend to be either rather practical, Iachng the formal background, or rather formal, lacking the connection to database practice, the gap between theory and practice has not been spanned yet. This paper proposes a complete extended relational algebra with multi-set semantics, having a clear formal background and a close connection to the standard relational algebra. It includes constructs that extend the algebra to a complete sequential database manipulation language...

• Type: Conference
• Year: 1994
• Where: ICDE
• Authors: Paul W. P. J. Grefen, Rolf A. de By
• Keywords: Database, Formal Background, ICDE 1994, Relational Algebra