Algebraic Meta-structure Handling of Huge Database Schemata

Practical experience shows that the maintenance of databases with a very large schema causes severe problems, and no systematic support is provided. In a recent study based on the analysis of a large number of very large database schemata twelve frequently recurring meta-structures were identified and classified into three categories associated with schema construction, lifespan and context. The systematic use of these meta-structures supports the modelling and maintenance of very large database schemata. In this paper we complement this study by a schema algebra that permits building larger schemata by composing smaller ones. Similar to abstraction mechanisms found in semantic data models the constructors can be classified into three groups for building associations and collections of subschemata, and for folding subschemata.