Extended Characteristic Sets: Graph Indexing for SPARQL Query Optimization

Author(s):  
Marios Meimaris ◽  
George Papastefanatos ◽  
Nikos Mamoulis ◽  
Ioannis Anagnostopoulos
2013 ◽  
Vol 441 ◽  
pp. 970-973
Author(s):  
Yan Qin Zhang ◽  
Jing Bin Wang

As the development of the semantic web, RDF data set has grown rapidly, thus causing the query problem of massive RDF. Using distributed technique to complete the SPARQL (Simple Protocol and RDF Query Language) Query is a new way of solving the large amounts of RDF query problem. At present, most of the RDF query strategies based on Hadoop have to use multiple MapReduce jobs to complete the task, resulting in waste of time. In order to overcome this drawback, MRQJ (using MapReduce to query and join) algorithm is proposed in the paper, which firstly uses a greedy strategy to generate join plan, then only one MapReduce job should be created to get the query results in SPARQL query execution. Finally, a contrast experiment on the LUBM (Lehigh University Benchmark) test data set is conducted, the results of which show that MRQJ method has a great advantage in the case that the query is more complicated.


Author(s):  
Zoi Kaoudi ◽  
Kostis Kyzirakos ◽  
Manolis Koubarakis

2020 ◽  
Vol 34 (03) ◽  
pp. 3057-3064
Author(s):  
Xiaowang Zhang ◽  
Jan Van den Bussche ◽  
Kewen Wang ◽  
Heng Zhang ◽  
Xuanxing Yang ◽  
...  

As a major query type in SPARQL, ASK queries are boolean queries and have found applications in several domains such as semantic SPARQL optimization. This paper is a first systematic study of the relative expressive power of various fragments of ASK queries in SPARQL. Among many new results, a surprising one is that the operator UNION is redundant for ASK queries. The results in this paper as a whole paint a rich picture for the expressivity of fragments of ASK queries with the four basic operators of SPARQL 1.0 possibly together with a negation. The work in this paper provides a guideline for future SPARQL query optimization and implementation.


Author(s):  
Vassilis Papakonstantinou ◽  
Giorgos Flouris ◽  
Irini Fundulaki ◽  
Andrey Gubichev

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