Authors: Amani Tahat, Maurice HT Ling
05/2011;
The relational model is the most commonly used data model for storing large
datasets, perhaps due to the simplicity of the tabular format which had
revolutionized database management systems.The relational model is the most commonly used data model for storing large
datasets, perhaps due to the simplicity of the tabular format which had
revolutionized database management systems. However, many real world objects
are recursive and associative in nature which makes storage in the relational
model difficult. The hypergraph model is a generalization of a graph model,
where each hypernode can be made up of other nodes or graphs and each hyperedge
can be made up of one or more edges. It may address the recursive and
associative limitations of relational model. However, the hypergraph model is
non-tabular; thus, loses the simplicity of the relational model. In this study,
we consider the means to convert a relational model into a hypergraph model in
two layers. At the bottom layer, each relational tuple can be considered as a
star graph centered where the primary key node is surrounded by non-primary key
attributes. At the top layer, each tuple is a hypernode, and a relation is a
set of hypernodes. We presented a reference implementation of relational
operators (project, rename, select, inner join, natural join, left join, right
join, outer join and Cartesian join) on a hypergraph model. Using a simple
example, we demonstrate that a relation and relational operators can be
implemented on this hypergraph model.
