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Showing 1 to 11 of 11 for “"Query evaluation"”.
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Query Evaluation Techniques for Data Integration Systems
In this work we present novel query evaluation techniques for data integration systems in different environments, ranging from a central data-warehouse approach, over distributed virtual market places, to peer-to-peer (P2P) systems. Based on a new distributed evaluation technique, the so-called …
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Towards trusted and efficient temporal relational databases
… and verifiable signatures. The database supports query evaluation over the entire timeline of the transaction log. To support efficient query evaluation, we utilize materialized snapshots at selected timestamps. We propose an optimal snapshot algorithm to compute the best timestamps so that the …
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LSPARQL: Transaction Time Queries in RDF
… using standard RDF is convoluted, and temporal query evaluation is inefficient. While there has been work on developing temporal triple stores that address these issues, there is generally a large cost associated with migrating to a new triplestore, especially if that triplestore is not being …
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Federated Query Processing for the Semantic Web
… specify directly what RDF data set they want to query, or making this process transparent to them). To overcome this heterogeneity in federated query processing solutions, the W3C SPARQL working group is defining a federation extension for SPARQL 1.1, which allows combining in a single query, …
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Systems and Techniques for Efficient Real-World Graph Analytics
… unexplored by existing graph engines for graph query optimization purposes. In addition, most temporal graph processing systems remain inefficient as they rely on distributed processing even for graphs that fit well within a commodity server’s available storage. To this end, we present two …
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The SUDO Framework: For Data Organization And Efficient Query Authorization For NoSQL Databases
… to simultaneously evaluate and authorize the query results.We present the SUDO framework in three parts. First, we present AReBAC, an attribute-supporting ReBAC model for Neo4j, a graph database. AReBAC focuses on weaving queries and policies for efficient authorization. AReBAC is also …
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Evaluating Temporal Queries over Videos
… and frames that have to be considered during query evaluation. Then, we consider the query with a ranking mechanism that aims to retrieve clips from large video repositories in which objects co-occur in a query-specified fashion. We propose a two-phased approach, where we build indexes during …
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A Geospatial Service Model and Catalog for Discovery and Orchestration
… data models, such as the capability to query using concept hierarchies. An example orchestration system demonstrates the use of the geospatial service catalog for query evaluation in an automatic orchestration system (both fully and semi-automatic orchestration). Computational complexity …
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Optimization Techniques for Complex Multi-query Applications
… and exploiting the CSEs to improve the query performance is essential in these applications. Multiple query optimization (MQO), which aims to identify the CSEs among multiple queries and exploit them to reduce the overall query evaluation cost, has been extensively studied for over two …
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Semantics and efficient evaluation of partial tree-pattern queries on XML
… keyword queries or using the standard structured query language XQuery the core of which consists of the navigational query language XPath. In this context, one major challenge is the querying of the data when the structure of the data sources is complex or not fully known to the user. Another …
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Schema-aware keyword search on linked data
Keyword search is a popular technique for querying the ever growing repositories of RDF graph data on the Web. This is due to the fact that the users do not need to master complex query languages (e.g., SQL, SPARQL) and they do not need to know the underlying structure of the data on the Web to …