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Handling Redundant Processing in OBDA Query Execution Over Relational Sources

23 Pages Posted: 11 Oct 2021 Publication Status: Accepted

See all articles by Dimitris Bilidas

Dimitris Bilidas

National and Kapodistrian University of Athens

Manolis Koubarakis

National and Kapodistrian University of Athens - Department of Informatics and Telecommunications

Abstract

Redundant processing is a key problem in the translation of initial queries posed over an ontology into SQL queries, through mappings, as it is performed by ontology-based data access systems. Examples of such processing are duplicate answers obtained during query evaluation, which must finally be discarded, or common expressions evaluated multiple times from different parts of the same complex query. Many optimizations that aim to minimize this problem have been proposed and implemented, mostly based on semantic query optimization techniques, by exploiting ontological axioms and constraints defined in the database schema. However, data operations that introduce redundant processing are still generated in many practical settings, and this is a factor that impacts query execution. In this work we propose a cost-based method for query translation, which starts from an initial result and uses information about redundant processing in order to come up with an equivalent, more efficient translation. The method operates in a number of steps, by relying on certain heuristics indicating that we obtain a more efficient query in each step. Through experimental evaluation using the Ontop system for ontology-based data access, we exhibit the benefits of our method.

Keywords: Query Translation, Data Integration, Ontology-Based Data Access, Ontop

Suggested Citation

Bilidas, Dimitris and Koubarakis, Manolis, Handling Redundant Processing in OBDA Query Execution Over Relational Sources. Journal of Web Semantics First Look , Available at SSRN: https://ssrn.com/abstract=3940363 or http://dx.doi.org/10.2139/ssrn.3940363

Dimitris Bilidas (Contact Author)

National and Kapodistrian University of Athens ( email )

5 Stadiou Strt
Athens, 12131
Greece

Manolis Koubarakis

National and Kapodistrian University of Athens - Department of Informatics and Telecommunications ( email )

Panepistimiopolis
Ilisia
Athens, GR15784
Greece

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