Filters








51,261 Hits in 3.4 sec

Datalog access to real-world web services

John Samuel
2018 Figshare  
Presentation slides of Logic for Dynamic Real-World Information Workshop, UNILOG 2018, Vichy, France, 25 June 2018  ...  GLAV (Global-Local as view) Languages used for Mapping Conjunctive query Union of conjunctive query Datalog query Advantages Declarative languages (Focus on what and not on how) Similar to SELECT-PROJECT-JOIN  ...  between local and global schema Mapping approaches: GAV (Global as view): Global schema is defined using local schema relations LAV (Local as view): Local schema is defined using global schema relations  ... 
doi:10.6084/m9.figshare.6707420.v1 fatcat:ucyfcr2i3rgkhczf4zyu64dera

Designing Views to Efficiently Answer Real SQL Queries [chapter]

Foto Afrati, Rada Chirkova, Manolis Gergatsoulis, Vassia Pavlaki
2005 Lecture Notes in Computer Science  
This paper presents results on selecting views to answer queries in relational databases under set, bag, and bag-set semantics.  ...  The results can be used under each of the three assumptions, to find sound and complete algorithms for designing views and rewriting queries efficiently.  ...  is said to be conjunctive if we consider the conjunctive language for queries, views and rewritings.  ... 
doi:10.1007/11527862_26 fatcat:r7pbsmncizghvht3nurhzzxpvy

ECQ: A Simple Query Language for the Semantic Web

Maria del Mar Roldan-Garcia, Joaquin J. Molina-Castro, Jose F. Aldana-Montes
2008 2008 19th International Conference on Database and Expert Systems Applications  
ECQ supports Tbox reasoning and complex queries, going beyond conjunctive queries, which are needed for real semantic web applications.  ...  In this paper we present ECQ (Extended Conjunctive Queries), a simple but powerful query language for OWL.  ...  We create views for each class and property in the ontology.  ... 
doi:10.1109/dexa.2008.131 dblp:conf/dexaw/GarciaMA08 fatcat:f4d5qxhiwnclvoe22jjkdh5tbi

Panorama: A database system that annotates its answers to queries with their properties

Amihai Motro
1996 Journal of Intelligent Information Systems  
determining the relevance of computed meta-information. (3) It is efficient: the number of operations required for meta-processing a given query can be expressed as a polynomial in the size of the meta-database  ...  When responding to queries, humans often volunteer additional information about their answers.  ...  Wang for their valuable comments.  ... 
doi:10.1007/bf00125522 fatcat:5jzaiqkrlfaopbdb6gxz7h3jcu

SWARD: Semantic Web Abridged Relational Databases

Johan Petrini, Tore Risch
2007 18th International Conference on Database and Expert Systems Applications (DEXA 2007)  
We have developed query processing techniques based on partial evaluation of query expressions as a way to enable execution of real-world queries to RDF views of relational databases.  ...  We have developed a system that can process queries to RDF views of large relational databases. This provides very flexible views of wrapped databases that can be queried using either RDQL or SQL.  ...  As real-world relational databases often have many columns, queries to the UPV require efficient processing of queries over large unions of many property views.  ... 
doi:10.1109/dexa.2007.125 dblp:conf/dexaw/PetriniR07 fatcat:asglxyhcenhs3jhw3d5eh6t4xm

SWARD: Semantic Web Abridged Relational Databases

Johan Petrini, Tore Risch
2007 Database and Expert Systems Applications  
We have developed query processing techniques based on partial evaluation of query expressions as a way to enable execution of real-world queries to RDF views of relational databases.  ...  We have developed a system that can process queries to RDF views of large relational databases. This provides very flexible views of wrapped databases that can be queried using either RDQL or SQL.  ...  As real-world relational databases often have many columns, queries to the UPV require efficient processing of queries over large unions of many property views.  ... 
doi:10.1109/dexa.2007.4312935 fatcat:wcpncqeanvhjffv2yq3ynysd5q

QueryMarket demonstration

Paraschos Koutris, Prasang Upadhyaya, Magdalena Balazinska, Bill Howe, Dan Suciu
2012 Proceedings of the VLDB Endowment  
To facilitate such transactions, online data marketplaces have emerged to provide a service for sellers to price views on their data, and buyers to buy such views.  ...  These marketplaces neither support the sale of ad-hoc queries (that are not one of the specified views), nor do they support queries that join datasets.  ...  QueryMarket allows sellers to assign prices to views defined by selection predicates of the form σa=α and allows buyers to purchase any query in a non-trivial subset of full conjunctive queries without  ... 
doi:10.14778/2367502.2367548 fatcat:rpkdoxqumjgujphon3brqrk5im

Smallest Set for Reverse Selection Queries to Satisfy All

Muhammed Miah
2017 International Journal of Science and Engineering Applications  
This paper considers the Smallest Set Reverse Selection Queries Problem also known as the Multiple Tuple Design Problem: Given a set of selection queries with conjunctive conditions, where the task is  ...  In recent years, research has moved from traditional query processing (e.g., Selection, Nearest Neighbor (NN), Top-k, Skyline), to reverse query processing (e.g., Reverse NN, Reverse Top-k, Reverse Skyline  ...  CONCLUSIONS This paper investigated the problem of designing smallest set of tuples for maximal reverse selection queries -given a set of selection queries with conjunctive conditions (where a query can  ... 
doi:10.7753/ijsea0603.1006 fatcat:xcntif4dk5aqfhg2iifxpfuexa

Efficiently Pinpointing SPARQL Query Containments [chapter]

Claus Stadler, Muhammad Saleem, Axel-Cyrille Ngonga Ngomo, Jens Lehmann
2018 Lecture Notes in Computer Science  
In contrast, our approach is fit for view selection use cases, and thus capable of efficiently enumerating all containment mappings among a set of queries.  ...  Query containment is a fundamental problem in database research, which is relevant for many tasks such as query optimisation, view maintenance and query rewriting.  ...  Acknowledgements This work was partly supported by the grant from the European Unions Horizon 2020 research Europe flag and innovation programme for the projects HOBBIT (GA no. 688227), QROWD (GA no. 732194  ... 
doi:10.1007/978-3-319-91662-0_16 fatcat:gclvxtqkmzbgdfmaga2uuvf4lm

Selecting and using views to compute aggregate queries

Foto Afrati, Rada Chirkova
2011 Journal of computer and system sciences (Print)  
For view selection, we prove complexity results.  ...  We look at query rewriting using existing views and at view selection. In the query-rewriting problem, we give sufficient and necessary conditions for a rewriting to exist.  ...  Complexity results for the view-selection problem for conjunctive queries and views without aggregation were presented in [9] .  ... 
doi:10.1016/j.jcss.2010.10.003 fatcat:6a6hrfuor5gxlferoxj4rqo4pm

Selecting and Using Views to Compute Aggregate Queries [chapter]

Foto Afrati, Rada Chirkova
2004 Lecture Notes in Computer Science  
For view selection, we prove complexity results.  ...  We look at query rewriting using existing views and at view selection. In the query-rewriting problem, we give sufficient and necessary conditions for a rewriting to exist.  ...  Complexity results for the view-selection problem for conjunctive queries and views without aggregation were presented in [9] .  ... 
doi:10.1007/978-3-540-30570-5_26 fatcat:hespmnsuyngd3e47fzisgofu7q

Integrity = validity + completeness

Amihai Motro
1989 ACM Transactions on Database Systems  
This article describes a uniform model of integrity for relational databases, that considers both validity and completeness.  ...  One of the features of the new model is the determination of the integrity of answers issued by the database system in response to user queries.  ...  First, views and queries are currently limited to conjunctive formulas.  ... 
doi:10.1145/76902.76904 fatcat:he4yezuqs5eyrautk3gkl354tu

Explainable security for relational databases

Gabriel Bender, Lucja Kot, Johannes Gehrke
2014 Proceedings of the 2014 ACM SIGMOD international conference on Management of data - SIGMOD '14  
We build on this foundation and implement a disclosure control system that handles a wide variety of real SQL queries and can accommodate complex policy constraints.  ...  Whether a query is accepted or denied, the system returns a concise yet formal explanation which can allow the issuer to reformulate a rejected query or adjust his/her security credentials.  ...  Any opinions, findings, conclusions or recommendations expressed in this paper are those of the authors and do not necessarily reflect the views of the sponsors.  ... 
doi:10.1145/2588555.2593663 dblp:conf/sigmod/BenderKG14 fatcat:qhtv6naewredddsktedgwrmuc4

Cost-based Optimization of Complex Scientific Queries

Ruslan Fomkin, Tore Risch
2007 International Conference on Scientific and Statistical Database Management  
We developed a cost model for aggregation operators and other functions used in such queries and show that it substantially improves performance.  ...  Each fragment is then independently profiled on a sample of events to measure real execution cost and cardinality.  ...  the queries into views.  ... 
doi:10.1109/ssdbm.2007.8 dblp:conf/ssdbm/FomkinR07 fatcat:544k6u6rjjhdlpw5m7n7jj23di

Answering queries using materialized views with minimum size

Rada Chirkova, Chen Li, Jia Li
2005 The VLDB journal  
We explore the decidability and complexity of the problem for workloads of conjunctive queries. We show that results differ significantly depending on whether the workload queries have self-joins.  ...  Further, for queries without self-joins we describe a very compact search space of views, which contains all views in at least one optimal viewset.  ...  Figure 7 shows how the accuracy changed for some selected views for queries P 5 , P 6 , and P 7 , where accuracy is defined as 1 − | size estimate − size real size real |.  ... 
doi:10.1007/s00778-005-0162-8 fatcat:oe3up45rebbavmiryh3jgfp3pi
« Previous Showing results 1 — 15 out of 51,261 results