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Index Support for SPARQL

by Ralf Heese, Ulf Leser, Bastian Quilitz, Christian Rothe
"... Abstract. The Resource Description Framework (RDF) is the fundamental data model underlying the Semantic Web. Recently, SPARQL has been proposed as W3C standard for querying RDF repositories. As RDF is a graph-based data model, the core problem of evaluating SPARQL queries is matching query graph pa ..."
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-patterns are contained in the query pattern, and derive formulas for estimating index selectivity. Finally, we study the problem of finding optimal sets of indexes for a given query. We believe that our framework is the first comprehensive suggestion for indexing RDF for SPARQL queries that goes beyond simple indexing

Towards Efficient SPARQL Query Processing on RDF Data *

by Liu Chang 刘 畅, Yu Yong 俞 勇
"... Abstract: Efficient support for querying large-scale resource description framework (RDF) triples plays an important role in semantic web data management. This paper presents an efficient RDF query engine to evaluate SPARQL queries, where the inverted index structure is employed for indexing the RDF ..."
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the RDF triples. A set of operators on the inverted index was developed for query optimization and evaluation. Then a main-tree-shaped optimization algorithm was developed that transforms a SPARQL query graph into the optimal query plan by effectively reducing the search space to determine the optimal

RDFMatView: Indexing RDF data using Materialized SPARQL Queries

by Roger Castillo, Christian Rothe, Ulf Leser - In International Workshop on Scalable Semantic Web Knowledge Base Systems (SSWS , 2010
"... Abstract. The Semantic Web aims to create a universal medium for the exchange of semantically tagged data. The idea of representing and querying this information by means of directed labelled graphs, i.e., RDF and SPARQL, has been widely accepted by the scientific community. However, even when most ..."
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joins and thus query processing time. We provide a formal definition of materialized SPARQL queries, a cost model to evaluate their impact on query performance, a storage scheme for the materialization, and an algorithm to find the optimal set of indexes given a query. We also present and evaluate

USING AN INDEX OF PRECOMPUTED JOINS IN ORDER TO SPEED UP SPARQL PROCESSING

by Volker Linnemann
"... Abstract: SparQL is a query language developed by the W3C, the purpose of which is to query a data set in RDF representing a directed graph. Many free available or commercial products already support SparQL processing. Current index-based optimizations integrated in these products typically construc ..."
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Abstract: SparQL is a query language developed by the W3C, the purpose of which is to query a data set in RDF representing a directed graph. Many free available or commercial products already support SparQL processing. Current index-based optimizations integrated in these products typically

ARQ Static Query Optimizer

by Markus Stocker, Andy Seaborne, Markus Stocker, Andy Seaborne , 2007
"... semantic web, SPARQL, query optimization In this paper we describe the architecture of ARQo, a first approach for SPARQL static query optimization in ARQ. Specifically, we focus on static optimization of BasicGraphPattern (BGP) for in-memory models. Static query optimization is intended as a query r ..."
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semantic web, SPARQL, query optimization In this paper we describe the architecture of ARQo, a first approach for SPARQL static query optimization in ARQ. Specifically, we focus on static optimization of BasicGraphPattern (BGP) for in-memory models. Static query optimization is intended as a query

Towards Graph Containment Search and Indexing

by Chen Chen, Xifeng Yan, Philip S. Yu, Jiawei Han, Dong-qing Zhang, Xiaohui Gu , 2007
"... Given a set of model graphs D and a query graph q, containment search aims to find all model graphs g ∈ D such that q contains g (q ⊇ g). Due to the wide adoption of graph models, fast containment search of graph data finds many applications in various domains. In comparison to traditional graph sea ..."
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capture the structure differences between model graphs and query graphs, and are thus perfect for indexing due to their high selectivity. Using a redundancy-aware feature selection process, cIndex can sort out a set of significant and distinctive contrast subgraphs and maximize its indexing capability. We

Rewriting Queries over Summaries of Big Data Graphs

by Mariano P. Consens, Valeria Fionda, Shahan Khatchadourian
"... This short paper reports on the benefits that traversal queries over existing graph stores (such as RDF databases) can gain from a class of optimizations based on summaries. Summaries, also known as structural indexes, have been extensively covered in the literature (see [2] for a brief overview). D ..."
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This short paper reports on the benefits that traversal queries over existing graph stores (such as RDF databases) can gain from a class of optimizations based on summaries. Summaries, also known as structural indexes, have been extensively covered in the literature (see [2] for a brief overview

Object/relational query optimization with chase

by Lucian Popa
"... and backchase ..."
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and backchase

GBLENDER: Towards blending visual query formulation and query processing in graph databases

by Changjiu Jin, Sourav S Bhowmick, Xiaokui Xiao, James Cheng - In SIGMOD , 2010
"... Given a graph database D and a query graph g, an exact subgraph matching query asks for the set S of graphs in D that contain g as a subgraph. This type of queries find important applications in sev-eral domains such as bioinformatics and chemoinformatics, where users are generally not familiar with ..."
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required in retrieving the result set S fromD, assum-ing that the whole query graph has been constructed. This leads to sub-optimal system response time as the query processing is initi-ated only after the user has finished drawing the query graph. In this paper, we take the first step towards exploring a

Representing and querying validity time in RDF and OWL: a logicbased approach. In:

by Boris Motik - Proceedings of the 9th international semantic web conference on The semantic web - Volume Part I. , 2010
"... Abstract. RDF(S) and OWL 2 currently support only static ontologies. In practice, however, the truth of statements often changes with time, and Semantic Web applications often need to represent such changes and reason about them. In this paper we present a logic-based approach for representing vali ..."
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validity time in RDF and OWL. Unlike the existing proposals, our approach is applicable to entailment relations that are not deterministic, such as the Direct Semantics or the RDF-Based Semantics of OWL 2. We also extend SPARQL to temporal RDF graphs and present a query evaluation algorithm. Finally, we
Results 1 - 10 of 85