Filters








937 Hits in 3.7 sec

Hierarchical Characteristic Set Merging for Optimizing SPARQL Queries in Heterogeneous RDF [article]

Marios Meimaris, George Papastefanatos
2018 arXiv   pre-print
Characteristic sets (CS) organize RDF triples based on the set of properties characterizing their subject nodes.  ...  In this paper, we address this problem by introducing a novel technique, for merging CSs based on their hierarchical structure.  ...  Each query CS q i matches with all tables whose property sets are supersets of the property set of q i .  ... 
arXiv:1809.02345v1 fatcat:6vuyp5oam5ezvhmpfzvybssm2q

Efficient Query Processing in RDF Databases [chapter]

Andrey Gubichev, Thomas Neumann
2014 Emerging Directions in Database Systems and Applications  
In this paper we show that the techniques borrowed from traditional SQL query optimization (such as Dynamic Programming algorithm or greedy heuristics) are not immediately capable of handling large SPARQL  ...  ., they represent RDF data as a single table with three attributes, at least conceptually), the query optimization strategies employed by such systems are often adopted from relational query optimization  ...  Sec. 4 describes our novel algorithm for star-shaped SPARQL query optimization.  ... 
doi:10.1201/b16859-8 fatcat:xu6mdl3uvnhmzcvzdbap2i2eiq

A Survey of RDF Stores SPARQL Engines for Querying Knowledge Graphs [article]

Waqas Ali, Muhammad Saleem, Bin Yao, Aidan Hogan, Axel-Cyrille Ngonga Ngomo
2021 arXiv   pre-print
techniques for efficiently evaluating SPARQL queries in a local setting (on one machine).  ...  RDF has seen increased adoption in recent years, prompting the standardization of the SPARQL query language for RDF, and the development of local and distributed engines for processing SPARQL queries.  ...  two query engines: SBQE, which is optimized for SPARQL 1.0-style queries, and MJQE, which features merge joins and caching techniques optimized for property paths.  ... 
arXiv:2102.13027v4 fatcat:phontczhbfcvdjt5y75n3hfcge

The Query Translation Landscape: a Survey [article]

Mohamed Nadjib Mami, Damien Graux, Harsh Thakkar, Simon Scerri, Sören Auer, Jens Lehmann
2019 arXiv   pre-print
In particular, we study which query language is a most suitable candidate for that 'universal' query language.  ...  In this article, we survey more than forty query translation methods and tools for popular query languages, and classify them according to eight criteria.  ...  MongoDB mappings relate MongoDB paths (e.g., student.name) to ontology properties. A SPARQL query is first decomposed into a set of translatable sub-queries.  ... 
arXiv:1910.03118v1 fatcat:wsww5vhlwjhqjlouibetb6mo3a

Scalable Multi-query Optimization for SPARQL

Wangchao Le, Anastasios Kementsietsidis, Songyun Duan, Feifei Li
2012 2012 IEEE 28th International Conference on Data Engineering  
In light of the NP-hardness of the multi-query optimization for SPARQL, we propose heuristic algorithms that partition the input batch of queries into groups such that each group of queries can be optimized  ...  We show that the techniques developed for relational and semi-structured data/query languages are hard, if not impossible, to be extended to account for RDF data model and graph query patterns expressed  ...  : In lines 5-30, we (incrementally) merge structurally similar queries within M through hierarchical clustering [14] , and generate query clusters such that each query cluster is optimized together (i.e  ... 
doi:10.1109/icde.2012.37 dblp:conf/icde/LeKDL12 fatcat:pbxaeplytrhgfkxpq2zt5lmzlq

Interactive construction of semantic widgets for visualizing semantic web data

Timo Stegemann, Jürgen Ziegler, Tim Hussein, Werner Gaulke
2012 Proceedings of the 4th ACM SIGCHI symposium on Engineering interactive computing systems - EICS '12  
Specifically, we propose X3S as a technique and format for specifying 'semantic widgets' that integrate querying and filtering of semantic data with defining their layout and presentation style.  ...  The rapidly growing amount of semantically represented data on the Web creates the need for more intuitive methods and tools to interact with these data and to use them in standard Web applications.  ...  To allow straightforward processing of the data, it should be re-structured into a hierarchical form. As the SPARQL results may contain redundancies, several result sets must also be merged.  ... 
doi:10.1145/2305484.2305510 dblp:conf/eics/StegemannZHG12 fatcat:ultrtsmjsrfdjjl46ut55zl4by

Distributed Query Processing in an Ad-hoc Semantic Web Data Sharing System

Jing Zhou, Gregor V. Bochmann, Zhongzhi Shi
2013 2013 IEEE International Symposium on Parallel & Distributed Processing, Workshops and Phd Forum  
Additionally, we propose efficient distributed processing of SPARQL queries in such a context and explore optimization techniques that build upon distributed query processing for database systems and relational  ...  The highly dynamic ad-hoc settings that would be pervasive for Semantic Web data sharing among personal users in the future, however, pose even more demanding challenges for the enabling technologies.  ...  Schmidt et al. identify a large set of algebraic equivalences for the SPARQL algebra which can serve as rewriting rules for query optimization [10] .  ... 
doi:10.1109/ipdpsw.2013.53 dblp:conf/ipps/ZhouBS13 fatcat:566c3zwxdvb2dpybqqa3fxd4re

Optimizing Analytical Queries over Semantic Web Sources [article]

Dilshod Ibragimov
2017 PhD series, Technical Faculty of IT and Design, ˜Aalborg=ålborgœ University  
Up to the moment, we have focused on the performance optimization techniques for aggregate SPARQL queries in stand-alone endpoints and in distributed settings.  ...  Section 5 introduces a cost-based query optimizer for aggregate queries over federations of SPARQL endpoints.  ... 
doi:10.5278/vbn.phd.tech.00022 fatcat:5d2lmnicazgmze2qhe5cikowwm

Knowledge Extraction from Structured Sources [chapter]

Jörg Unbehauen, Sebastian Hellmann, Sören Auer, Claus Stadler
2012 Lecture Notes in Computer Science  
This work was partially supported by a grant from the European Union's 7th Framework Programme provided for the project LOD2 (GA no. 257943).  ...  Acknowledgments We would like to thank our colleagues from AKSW research group for their helpful comments and inspiring discussions during the development of SparqlMap.  ...  For the two sets of triple pattern bindings TPB 1 and TPB 2 we define two merge operations for the triple pattern bindings as follows: Binding merge merge(TPB 1 , TPB 2 ) reduces all triple pattern bindings  ... 
doi:10.1007/978-3-642-34213-4_3 fatcat:txmhb6vgpvhhxhluad66efalza

An Agglomerative-adapted Partition Approach for Large-scale Graphs

Chen Tao, Rongrong Shan, Hui Li, Dongsheng Wang, Wei Liu
2019 International Journal of Librarianship (IJoL)  
This paper presents an agglomerative-adapted approach for large-scale graphs, which is also a bottom-up merging process.  ...  In the future, we will research the automation setting of the number of partitions with machine learning algorithms.  ...  8 . 8 The reformation tree for Bibliographic platform Figure 9 . 9 Partitions comparison of different degrees for Bibliographic platform entityMaps<node, cost> <-perform this SPARQL query and save  ... 
doi:10.23974/ijol.2019.vol4.1.106 fatcat:lxhzzyvterbrxajff65br3vz2e

Incremental Hierarchical Clustering driven Automatic Annotations for Unifying IoT Streaming Data

Sivadi Balakrishna, M. Thirumaran, Vijender Kumar Solanki, Edward Núñez-Valdez
2020 International Journal of Interactive Multimedia and Artificial Intelligence  
However, many of the existing semantic annotation mechanisms require many joint conditions that could generate redundant processing of transitional results for annotating the sensor data using SPARQL queries  ...  In this paper, we present an Incremental Clustering Driven Automatic Annotation for IoT Streaming Data (IHC-AA-IoTSD) using SPARQL to improve the annotation efficiency.  ...  Query Optimizer This is the second subcomponent and generates a Query Execution Plan (QEP) for the SPARQL query.  ... 
doi:10.9781/ijimai.2020.03.001 fatcat:niismfrs4fbrngkjzth32i3tzy

Storage, Indexing, Query Processing, and Benchmarking in Centralized and Distributed RDF Engines: A Survey [article]

Waqas Ali, Muhammad Saleem, Bin Yao, Aidan Hogan, Axel-Cyrille Ngonga Ngomo
2020 arXiv   pre-print
The type of the underlying querying language (e.g., SPARQL or SQL) used for query execution is a crucial optimization component of the RDF storage solutions.  ...  For example, the storage of RDF data in various ways significantly affects the data storage space required and the query runtime performance.  ...  Merge joins are used extensively in the generated optimized query execution plans. DB2RDF [15] uses a relational schema consisting of property tables to store RDF data.  ... 
arXiv:2009.10331v2 fatcat:ou4nctjyj5c6jbh4osclewj62e

Improving the Data Quality of Drug Databases using Conditional Dependencies and Ontologies

Olivier Curé
2012 Journal of Data and Information Quality  
We also present a solution for representing conditional dependencies using a query language defined for these graph oriented structures, namely SPARQL.  ...  But they are generally not expressive enough to represent a domain specific set of constraints.  ...  a set of SPARQL queries.  ... 
doi:10.1145/2378016.2378019 dblp:journals/jdiq/Cure12 fatcat:spepfriflnhqrjpwrvcacvlxoy

Scalable Semantics – The Silver Lining of Cloud Computing

Andrew Newman, Yuan-Fang Li, Jane Hunter
2008 2008 IEEE Fourth International Conference on eScience  
We then present some implementation details for our MapReduce-based RDF molecule store.  ...  Semantic inferencing and querying across largescale RDF triple stores is notoriously slow.  ...  We developed optimized algorithms to losslessly decompose an RDF graph into a set of smaller "molecules" and subsequently merge them.  ... 
doi:10.1109/escience.2008.23 dblp:conf/eScience/NewmanLH08 fatcat:xmeh3hi5mfdl3l2ekz7qdh54u4

RDF data management in the Amazon cloud

Francesca Bugiotti, François Goasdoué, Zoi Kaoudi, Ioana Manolescu
2012 Proceedings of the 2012 Joint EDBT/ICDT Workshops on - EDBT-ICDT '12  
The goal of the index is to efficiently identify the RDF datasets which may have answers for a given query, and route the query only to those.  ...  Cloud computing has been massively adopted recently in many applications for its elastic scaling and fault-tolerance.  ...  For instance, for the SPARQL query of Listing 1, we define the following SimpleDB queries for each domain i: The datasets retrieved from queries q1 and q2 then merged and the SPARQL query is evaluated  ... 
doi:10.1145/2320765.2320790 dblp:conf/edbt/BugiottiGKM12 fatcat:indrvx522bdjne3ubra5devqly
« Previous Showing results 1 — 15 out of 937 results