Aggregation query model for OODBMS

Query language and querying facilities are critical factors for wide acceptance of Object-Oriented Database Management Systems (OODBMS) in the market. In this paper, we focus on query model on an aggregation hierarchy. We call this query "Aggregation Query". Query on an aggregation hierarchy is unique and differs from general query on association relationships. The latter is often known as path expression query. The difference is analogous to the distinction between association and aggregation in object modelling. In our proposal, we present three important elements of aggregation query, particularly (i) aggregation query hierarchy, (ii) shorthand path expression for aggregation query utility, and (iii) retrieving aggregation tree. Whilst the first element above is adopted from path expression queries, the second element is an extension to general path expression query, and the third element is unique to aggregation, as aggregation resembles a Part-Of relationship, which is more specialized than association relationships.