An extended ER algebra to support semantically richer queries in ERDBMS

Abstract

In this paper we present the foundations for a semantically rich main-memory DBMS based on the entity-relationship data model. The DBMS is fully operational and performs all queries that are illustrated in the paper. So far, the ER model is mainly used as a conceptual model and mapped into the relational model. Semantics like the relationships among entities or the cardinality ratio constraints are not explicit in the relational model. This paper treats the ER model as a logical model for the user and we use the relational as the physical model in our ER model based DBMS - ERDBMS. We use CISC (complex instruction set computing) operators but implement them efficiently in main-memory data storage. This paper concentrates on the extended ER algebra. Our high-level query language ERSQL and the main memory implementation are elaborated in [14].