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Nested Constructs vs. Sub-Selects in SPARQL

Axel Polleres, Juan L. Reutter, Egor V. Kostylev
2016 Alberto Mendelzon Workshop on Foundations of Data Management  
Particularly, nested CONSTRUCT in FROM clauses are a feature that has been discussed as a potential input for SPARQL 1.1 which was resolved to be left out in favour of select subqueries under the-unproven-conjecture  ...  In this paper, we show that it is indeed possible to unfold nested SPARQL construct queries into subqueries in SPARQL 1.1; our transformation, however, requires an exponential blowup in the nesting depth  ...  While nested select queries are allowed in SPARQL 1.1, other forms of subqueries such as nested CONSTRUCT queries in FROM clauses, as proposed in [2, 9] , were not included to the new specification under  ... 
dblp:conf/amw/PolleresRK16 fatcat:tjmt5ghuwva2bdvqrf4ibssxpq

From SPARQL to MapReduce: The Journey Using a Nested TripleGroup Algebra

HyeongSik Kim, Padmashree Ravindra, Kemafor Anyanwu
2011 Proceedings of the VLDB Endowment  
However, one major challenge is that this computational paradigm leads to high I/O and communication costs when processing tasks with several join operations typical in SPARQL queries.  ...  The goal of this demonstration is to show how a system RAPID+, an extension of Apache Pig, enables more efficient SPARQL query processing on MapReduce using an alternative query algebra called the Nested  ...  In this demonstration, we will use pattern matching SPARQL queries with varying sub structures.  ... 
dblp:journals/pvldb/KimRA11 fatcat:2aj7v7tgfbdrbbtubpgilb6m5e

Reasoning over SPARQL

Sam Coppens, Miel Vander Sande, Ruben Verborgh, Erik Mannens, Rik Van de Walle
2013 The Web Conference  
In this paper, we propose an extension to the sparql query language to support remote reasoning, in which the data consumer can define the inference rules.  ...  However, in this case the sparql endpoint provider decides which inference rules are used for its entailment regimes.  ...  ACKNOWLEDGEMENTS The research activities that have been described in this paper were funded by Ghent University, iMinds, the Institute for the Promotion of Innovation by Science and Technology in Flanders  ... 
dblp:conf/www/CoppensSVMW13 fatcat:eflaavyt4ncatcxjlk7mpqxcfu

Ephedra: Efficiently Combining RDF Data and Services Using SPARQL Federation [chapter]

Andriy Nikolov, Peter Haase, Johannes Trame, Artem Kozlov
2017 Communications in Computer and Information Science  
SPARQL queries performance.  ...  In this paper we describe representative use cases of metaphacts in the cultural heritage and pharmacy domains and the hybrid information needs arising in them.  ...  Processing such service calls in the same way as genuine SPARQL endpoints would result in sub-optimal query runtimes or even failing queries.  ... 
doi:10.1007/978-3-319-69548-8_17 fatcat:4xbpne6mwndyfilcranyllp2im

Extended UML Class Diagram Constructs for Visual SPARQL Queries in ViziQuer/web

Karlis Cerans, Juris Barzdins, Agris Sostaks, Julija Ovcinnikova, Lelde Lace, Mikus Grasmanis, Arturs Sprogis
2017 International Semantic Web Conference  
We propose a number of constructs for extending the basic diagrammatic framework in the setting of visual specification of SPARQL select queries for enabling visual specification of hierarchic data instance  ...  to data instances, and (iv) integration with textual SPARQL fragments.  ...  Expressivity and Limitations Apart from the possibility to include direct SPARQL graph patterns and full SPARQL select sub-queries in the query node compartments, there are explicit counterparts for most  ... 
dblp:conf/semweb/CeransBSOLGS17 fatcat:fs3fdacirvbarcbhdxdsobghsu

SQUALL: The expressiveness of SPARQL 1.1 made available as a controlled natural language

Sébastien Ferré
2014 Data & Knowledge Engineering  
SQUALL provides a lot of syntactic flexibility in that a same SPARQL query/update can be expressed in many different ways.  ...  In this setting, SQUALL is less natural at the lexical level, but applicable to SPARQL endpoints without any preparation.  ...  I also thank Benjamin Sigonneau for his help in the development and deployment of Web forms, and Jean-Marc Vanel for integrating SQUALL in his tool, EulerGUI, and for suggesting useful features.  ... 
doi:10.1016/j.datak.2014.07.010 fatcat:geccpeobvne4pnacgt3qbgwnlu

Left Bit Right

Medha Atre
2015 Proceedings of the 2015 ACM SIGMOD International Conference on Management of Data - SIGMOD '15  
In this paper, we present Left Bit Right (LBR), a technique for well-designed nested BGP and OPTIONAL pattern queries.  ...  SPARQL basic graph pattern (BGP) (a.k.a. SQL inner-join) query optimization is a well researched area. However, optimization of OPTIONAL pattern queries (a.k.a.  ...  Sudeepa Roy for their valuable inputs, and the three anonymous reviewers for their detailed feedback, which significantly helped us in improving the presentation of our paper.  ... 
doi:10.1145/2723372.2746483 dblp:conf/sigmod/Atre15 fatcat:ftc4qr57yncovemfsbxxsot25q

Algebra of RDF Graphs for Querying Large-Scale Distributed Triple-Store [chapter]

Iztok Savnik, Kiyoshi Nitta
2016 Lecture Notes in Computer Science  
Large-scale RDF graph databases stored in shared-nothing clusters require query processing engine that can effectively exploit highly parallel computation environment.  ...  This is presented in more detail in Sub-section 4.2. Physical algebra operations AM, join, union, intsc and diff are implemented in query-node modules.  ...  We say that RDF graph g 1 is sub-graph of g 2 , denoted g 1 g 2 , if all triples in g 1 are also triples from g 2 .  ... 
doi:10.1007/978-3-319-45507-5_1 fatcat:f2ryd5mhsnf47f3cv5kfponv2e

A Stitch in Time Saves Nine -- SPARQL querying of Property Graphs using Gremlin Traversals [article]

Harsh Thakkar and Dharmen Punjani and Yashwant Keswani and Jens Lehmann and Sören Auer
2018 arXiv   pre-print
We present Gremlinator, a novel SPARQL to Gremlin translator. Gremlinator translates SPARQL queries to Gremlin traversals for executing graph pattern matching queries over graph databases.  ...  However, the query languages for these two data models -- SPARQL for RDF and Gremlin for property graph traversal -- are lacking interoperability.  ...  In SPARQL, GPM is conducted by matching BGPs which consist of triple patterns (TP), that form a sub-graph, against an RDF graph G (i.e. checking whether a sub-graph is contained in G).  ... 
arXiv:1801.02911v2 fatcat:nz2kgbff7zfkbhocnrhelo5bfu

SQUALL: A Controlled Natural Language as Expressive as SPARQL 1.1 [chapter]

Sébastien Ferré
2013 Lecture Notes in Computer Science  
SQUALL is available as two web services: one for translating a SQUALL sentence to a SPARQL query or update, and another for directly querying a SPARQL endpoint such as DBpedia.  ...  The most common approach to access RDF datasets is through SPARQL, an expressive query language.  ...  The semantics is defined in a fully compositional style, i.e., the semantics of a construct is always a composition of the semantics of sub-constructs.  ... 
doi:10.1007/978-3-642-38824-8_10 fatcat:vgmi7nwd7zbxxhoq76gl33wjje

RDF Querying: Language Constructs and Evaluation Methods Compared [chapter]

Tim Furche, Benedikt Linse, François Bry, Dimitris Plexousakis, Georg Gottlob
2006 Lecture Notes in Computer Science  
For this article, the following RDF query languages have been, admittedly subjectively, selected: Firstly, the "relational" or "pattern-based" query languages SPARQL, RQL, TRIPLE, and Xcerpt; secondly  ...  The inheritance model of RDFS exhibits the following peculiarities: 1. resources can be classified in different classes that are not related in the class hierarchy, 2. the class hierarchy can be cyclic  ...  Graph Construction vs.  ... 
doi:10.1007/11837787_1 fatcat:juhw5xa3vfhdfga42e4gxxio6u

A Mapping-Based Method to Query MongoDB Documents with SPARQL [chapter]

Franck Michel, Catherine Faron-Zucker, Johan Montagnat
2016 Lecture Notes in Computer Science  
Therefore, in this paper we address the question of how to access arbitrary MongoDB documents with SPARQL.  ...  We propose a two-step method to (i) translate a SPARQL query into a pivot abstract query under MongoDB-to-RDF mappings represented in the xR2RML language, then (ii) translate the pivot query into a concrete  ...  By construction, rule R6 ensures that where clauses cannot be nested in an elemmatch, but they may show in and and or clauses.  ... 
doi:10.1007/978-3-319-44406-2_6 fatcat:axufio6jhzdujczsktwvovb4jm

Rewriting queries on SPARQL views

Wangchao Le, Songyun Duan, Anastasios Kementsietsidis, Feifei Li, Min Wang
2011 Proceedings of the 20th international conference on World wide web - WWW '11  
In this paper, we present the first native query rewriting algorithm for SPARQL.  ...  The problem of answering SPARQL queries over virtual SPARQL views is commonly encountered in a number of settings, including while enforcing security policies to access RDF data, or when integrating RDF  ...  ACKNOWLEDGMENT This work was done in part when Wangchao Le (intern) and Min Wang were with IBM. Wangchao Le and Feifei Li were partially supported by NSF Grant CNS-0831278.  ... 
doi:10.1145/1963405.1963497 dblp:conf/www/LeDKLW11 fatcat:2n2hzhilqrc3hmtq33lar6xnrm

The SPARQL2XQuery Interoperability Framework. Utilizing Schema Mapping, Schema Transformation and Query Translation to Integrate XML and the Semantic Web [article]

Nikos Bikakis, Chrisa Tsinaraki, Ioannis Stavrakantonakis, Nektarios Gioldasis, Stavros Christodoulakis
2014 arXiv   pre-print
In this environment, organizations and companies adopt the Linked Data practices utilizing Semantic Web (SW) technologies, in order to publish their data and offer SPARQL endpoints (i.e., SPARQL-based  ...  In this direction, we introduce the SPARQL2XQuery Framework which creates an interoperable environment, where SPARQL queries are automatically translated to XQuery queries, in order to access XML data  ...  SPARQL allows four query forms: Select, Ask, Construct and Describe.  ... 
arXiv:1311.0536v3 fatcat:hrwu4zaarngqpcpfti2mrh63v4

A fine-grained evaluation of SPARQL endpoint federation systems

Muhammad Saleem, Yasar Khan, Ali Hasnain, Ivan Ermilov, Axel-Cyrille Ngonga Ngomo, Axel Polleres
2016 Semantic Web Journal  
In particular, we consider the number of sources selected, the total number of SPARQL ASK requests used, the completeness of answers as well as the source selection time.  ...  In this work, we perform extensive experiments to compare state-of-the-art SPARQL endpoint federation systems using the comprehensive performance evaluation framework FedBench.  ...  . = Source Selection Type, I.U. = Index/catalog Update, (A+I) = SPARQL ASK and Index/catalog, (C+L) = Catalog and online discovery via Link-traversal ), VENL = Vectored Evaluation in Nested Loop, AGJ =  ... 
doi:10.3233/sw-150186 fatcat:dmz6yqxemrgwhfnci3weaeitka
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