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EAV: An Algebra for the Representation and

Realization of Internal, Conceptual Objects in

Configurable Database Management Systems

Andreas Geppert, Klaus R. Dittrich

Technical Report 93.25

Institut f?r Informatik, Universit?t Z?rich

Winterthurerstr. 190

CH-8057 Z?rich, Switzerland

{geppert, dittrich}

July 31, 1992
Revised Version May 24, 1993


The aim of the KIDS1 project is the specification and generation/configuration of database management systems (DBMS). Thus, as for one aspect of KIDS, the modelling of potentially arbitrarily structured (generic) objects on different levels of abstraction has to be supported. First, a meta model provides for the description of data and operations close to the view of the user. Second, data are represented as physical objects on the storage level. Hence, a mapping from data model objects into physical objects is desired. Since that mapping is likely to get very complex, an intermediate representation is introduced, and the mapping is subdivided into two steps. On the intermediate level, data is represented in the form of triples (entity, attribute, values) or as quadruples (which allow the ordering of specific sets of triples). Triples are comparable to logical objects in database management systems: neither are they stored physically, nor are they visible to users. The description of data model objects results in a triple scheme, while the semantics of data model operations can be expressed in terms of operations on triple sets. Furthermore, the way sets of triples have to be stored is specified by means of reduction rules. The EAV2 algebra supports the specification of triples and quadruples, operations on sets of triples, and the definition of (reduction) rules by use of algebraic expressions.

1. Kernel Machine-Based Implementation of Database Management Systems
2. Entity-Attribute-Value