Book Image

NoSQL Data Models

By : Olivier Pivert
Book Image

NoSQL Data Models

By: Olivier Pivert

Overview of this book

Big Data environments are now to be handled in most current applications, this book addresses the latest issues and hurdles that are encountered in such environments. The book begins by presenting an overview of NoSQL languages and systems. Then, you’ll evaluate SPARQL queries over large RDF datasets and devise a solution that will use the MapReduce framework to process SPARQL graph patterns. Next, you’ll handle the production of web data, generate a set of links between two different datasets and overcome different heterogeneity problems. Moving ahead, you’ll take the multi-graph based approach to overcome challenges faced by the RDF data management community. Finally, you’ll deal with the flexible querying of graph databases and textual data management. By the end of this book, you’ll have gathered essential information on big data challenges faced by NoSQL databases.
Table of Contents (11 chapters)
Preface
8
List of Authors
9
Index
10
End User License Agreement

5.3. Background and preliminaries

In this section, we provide basic definitions on the interplay between RDF and its multigraph representation. Later, we explain how the task of answering SPARQL queries can be reduced to a multigraph homomorphism problem.

5.3.1. RDF data

According to the W3C standards3, RDF data are represented as a set of triples <S,P,O>, as shown in Figure 5.1(a), where each triple <s,p,o> consists of the following three components: a subject, a predicate and an object. Further, each component of the RDF triple can be either of the two forms: an IRI (Internationalized Resource Identifier) or a literal. For brevity, an IRI is usually written with a prefix (e.g. <http://dbpedia.org/resource/isPartOf> is written as “x:isPartOf”), whereas a literal is always written with double quotes (e.g. “90000”). While a subject s and a predicate p are always an IRI, an object o can be either an IRI or a literal.

RDF data can also be represented...