A DBMS prototype to support extended NF2 relations: an integrated view on flat tables and hierarchies

TLDR

Extensions to relational database management systems have been proposed to support hierarchical structures, but existing implementations built on top of current DBMSs suffer conceptual and performance disadvantages. This paper reports a three‑year effort to design and prototype a DBMS that supports a generalized relational data model, the extended NF2 model, which treats flat tables, lists, and hierarchies uniformly. The authors present a logical data model, a language for the model, and discuss alternative storage structures for implementing generalized relations.

Abstract

Recently, extensions for relational database management systems (DBMS) have been proposed to support also hierarchical structures (complex objects). These extensions have been mainly implemented on top of an existing DBMS. Such an approach leads to many disadvantages not only from the conceptual point of view but also from performance aspects. Thus paper reports on a 3-year effort to design and prototype a DBMS to support a generalized relational data model, called extended NF 2 ( N on F irst N ormal F orm) data model which treats flat relations, lists, and hierarchical structures in a uniform way. The logical data model, a language for this model, and alternatives for storage structures to implement generalized relations are presented and discussed.