Database Optimization Techniques for Semantic Queries

• Main Author: Manolescu, Ioana
• Other Authors: Laboratoire de Recherche en Informatique (LRI), Université Paris-Sud - Paris 11 (UP11)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Database optimizations and architectures for complex large data (OAK), Université Paris-Sud - Paris 11 (UP11)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS)-Inria Saclay - Ile de France, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)
• Format: Conference Object
• Language: English
• Published: HAL CCSD 2015
• Subjects: Semantic Web; Databases; Query Optimization; ACM: H.: Information Systems/H.2: DATABASE MANAGEMENT/H.2.3: Languages/H.2.3.3: Query languages; ACM: H.: Information Systems/H.2: DATABASE MANAGEMENT/H.2.3: Languages/H.2.3.0: Data description languages (DDL); ACM: H.: Information Systems/H.2: DATABASE MANAGEMENT/H.2.3: Languages/H.2.3.1: Data manipulation languages (DML); [INFO.INFO-DB]Computer Science [cs]/Databases [cs.DB]; DML
• Online Access: https://hal.inria.fr/hal-01179477; https://hal.inria.fr/hal-01179477/document; https://hal.inria.fr/hal-01179477/file/keynote.pdf

International audience Techniques for efficiently managing Semantic Web data have attracted significant interest from the data management and knowledge representation communities. In particular, as RDF is the most widely used model for Semantic Web data, a great deal of effort has been invested, especially in the database community, into algorithms and tools for efficient RDF query evaluation. Semantic Web data can be seen as a colection of facts enriched with ontological schemas, or semantic constraints, based on which reasoning can be applied to infer new information. Taking into account this implicit information is required in order to produce complete answers to queries. The difficulty in doing so depends on the expressive power of the constraints being used to describe the semantics of the data. One of the simplest constraint languages currently used in conjunction with RDF databases is RDF Schema (RDFS, in short), whose core consists of the rdfs:subClassOf, rdfs:subPropertyOf, rdfs:domain and rdfs:range predefined predicates, which allow characterizing the relationships between classes (unary relations) and properties (binary relations). More expressive formal constraints languages can be found in the DL-Lite family [6], the Datalog ± dialect [5] etc. The literature provides two classes of techniques for implementing reasoning , namely query reformulation and database saturation. The former consists of compiling the constraints into the query, making it syntactically more complex , while the latter compiles the constraints into the data, i.e., it adds all the consequences of the facts and the constraints to the database. The performance of these techniques depends on the expressive power of the ontological schema language, as well as on the characteristics of the data and queries. While saturation appears simple and robust, it is not always feasible and it may also perform poorly, especially in a distributed setting. Efficient query answering through FOL reformulation This talk describes some of our ...