Query Processing using Ontologies

Traditional approaches to query processing aim at rewriting a given query into another more efficient one that uses less time and/or resources during the execution. There by, the rewritten query must be equivalent to the initial one, i.e., it must provide the same result. However, rewriting queries in equivalent ways do not always satisfy the user’s needs, in particular when the user does not receive any answer at all. The goal of this work is to develop a new approach for query processing which allows to rewrite a query into another one which is not necessary equivalent but can provide more meaningful result satisfying the user’s intention. The approach is based on the use of semantic knowledge in form of ontologies for a meaningful processing. We develop a set of rewriting rules which rely on semantic information extracted form the ontology associated with the database and the mapping information that relate ontology components with database objects. Hence, our approach can provide supports to DBMSs for manipulating queries not only at the syntactical level but also at the semantical one.