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Correctness of SQL Queries on Databases with Nulls

Paolo Guagliardo, Leonid Libkin
2017 SIGMOD record  
However, SQL evaluation can be modified, at least for relational algebra queries, to approximate certain answers, i.e., return only correct answers.  ...  Having efficiency as its main goal, SQL disregards the standard notion of correctness on incomplete databases -certain answers -due to its high complexity.  ...  APPROXIMATION SCHEMES WITH CORRECTNESS GUARANTEES Due to the high complexity of certain answers, we must settle for approximations that can be computed efficiently.  ... 
doi:10.1145/3156655.3156657 fatcat:ayak6sw7zvartmstd4s2kq7nam

Query processing over incomplete autonomous databases: query rewriting using learned data dependencies

Garrett Wolf, Aravind Kalavagattu, Hemal Khatri, Raju Balakrishnan, Bhaumik Chokshi, Jianchun Fan, Yi Chen, Subbarao Kambhampati
2009 The VLDB journal  
Consequently, it is suitable for querying incomplete autonomous databases, given a mediator 's query-only capabilities and limited query access patterns to these databases.  ...  Our Approach: In this paper, we present QPIAD, 3 a system for mediating over incomplete autonomous databases.  ...  Related Work and Discussion Querying Incomplete Databases: The need of returning maybe answers besides certain answers when querying incomplete databases has been well recognized for a long time [23  ... 
doi:10.1007/s00778-009-0155-0 fatcat:hkoyyibu55bmfnq6gmqbthphee

Relational confidence bounds are easy with the bootstrap

Abhijit Pol, Christopher Jermaine
2005 Proceedings of the 2005 ACM SIGMOD international conference on Management of data - SIGMOD '05  
This paper considers the problem of incorporating into a database system a powerful "plug-in" method for computing confidence bounds on the answer to relational database queries over sampled or incomplete  ...  Statistical estimation and approximate query processing have become increasingly prevalent applications for database systems.  ...  Both of these problems are related to the fact that the TA algorithm first resamples the incomplete relations, and then computes the answer to the query.  ... 
doi:10.1145/1066157.1066224 dblp:conf/sigmod/PolJ05 fatcat:ui45cpzwdjbs7kgwanrzce4bha

Negative Knowledge for Certain Query Answers [chapter]

Leonid Libkin
2016 Lecture Notes in Computer Science  
Second, we show that approximations of such certain information can be computed efficiently for all first-order queries over relational databases.  ...  Querying incomplete data usually amounts to finding answers we are certain about.  ...  Acknowledgments I am grateful to anonymous referees for their comments. This work was partly supported by EPSRC grants J015377 and M025268.  ... 
doi:10.1007/978-3-319-45276-0_9 fatcat:5v72lhcyefcovijbwzybmbi2um

Research Directions for Principles of Data Management (Dagstuhl Perspectives Workshop 16151) [article]

Serge Abiteboul, Marcelo Arenas, Pablo Barceló, Meghyn Bienvenu, Diego Calvanese, Claire David, Richard Hull, Eyke Hüllermeier, Benny Kimelfeld, Leonid Libkin, Wim Martens, Tova Milo, Filip Murlak (+6 others)
2017 arXiv   pre-print
The workshop was organized jointly by the Executive Committee of the ACM Symposium on Principles of Database Systems (PODS) and the Council of the International Conference on Database Theory (ICDT).  ...  The mission of this workshop was to identify and explore some of the most important research directions that have high relevance to society and to Computer Science today, and where the PDM community has  ...  Typically, answering queries over incomplete databases with certainty can be done efficiently for conjunctive queries or some closely related classes, but beyond the complexity quickly grows to intractable  ... 
arXiv:1701.09007v1 fatcat:cr76noeh4nazlbxuvo7cqrusre

A Model for Processing Skyline Queries in Crowd-sourced Databases

Marwa B. Swidan, Ali A. Alwan, Sherzod Turaev, Yonis Gulzar
2018 Indonesian Journal of Electrical Engineering and Computer Science  
This paper attempts to present an efficient model tackling the issue of processing skyline queries in incomplete crowd-sourcing database.  ...  Therefore, an efficient approach processing skyline queries with partial incomplete data in crowd-sourcing database is needed.  ...  Skyline Queries for Incomplete Data There are numerous algorithms which applied skyline queries for incomplete database.  ... 
doi:10.11591/ijeecs.v10.i2.pp798-806 fatcat:qjowjcwlondzhbx6fismf3xtzq

On Querying Incomplete Information in Databases under Bag Semantics

Marco Console, Paolo Guagliardo, Leonid Libkin
2017 Proceedings of the Twenty-Sixth International Joint Conference on Artificial Intelligence  
For positive queries, expressed either in positive relational algebra or as unions of conjunctive queries, finding such answers can be done efficiently when databases and query answers are sets.  ...  Querying incomplete data is an important task both in data management, and in many AI applications that use query rewriting to take advantage of relational database technology.  ...  Acknowledgments We thank the anonymous referees for their comments. Work supported by EPSRC grants N023056 and M025268.  ... 
doi:10.24963/ijcai.2017/138 dblp:conf/ijcai/ConsoleGL17 fatcat:glp3z2bjw5hqpnqk6msqndz2ae

Parallel and Progressive Approaches for Skyline Query Over Probabilistic Incomplete Database

Yifu Zeng, Kenli Li, Shui Yu, Yantao Zhou, Keqin Li
2018 IEEE Access  
Therefore, a parallel progressive skyline query algorithm for incomplete databases is imperative, which provides answers gradually and much faster.  ...  However, the existing algorithms are unable to address incomplete probabilistic databases. In addition, it is necessary to wait for query completion to obtain even partial results.  ...  Line 10 to line 36 are the main processing flow that are illustrated above. With Algorithm 5, a probabilistic incomplete database can be processed to a set of skyline answers efficiently. V.  ... 
doi:10.1109/access.2018.2806379 fatcat:6i3d5vjipfgbbfbroei4l45oje

Enhancing Keyword Query Results Over Database for Improving User Satisfaction

Priya Pujari, Roshani Ade
2016 International Journal of Managing Public Sector Information and Communication Technologies  
Storing data in relational databases is widely increasing to support keyword queries but search results does not gives effective answers to keyword query and hence it is inflexible from user perspective  ...  Here we estimate prediction of query performance to find out effectiveness of a search performed in response to query and features of such hard queries is studied by taking into account contents of the  ...  ACKNOWLEDGEMENTS The authors would like to thank all the members for their expert guidance and all others who directly or indirectly helped and made numerous suggestions which improved the quality of this  ... 
doi:10.5121/ijmpict.2016.7203 fatcat:emnut3yvcvhurpwqorvy3qeywe

Coping with Incomplete Data: Recent Advances

Marco Console, Paolo Guagliardo, Leonid Libkin, Etienne Toussaint
2020 Proceedings of the 39th ACM SIGMOD-SIGACT-SIGAI Symposium on Principles of Database Systems  
Finally, the third author is grateful to Foundation Sciences Mathématiques de Paris for supporting his stay in Paris in the Fall of 2019, during which some of this work was done.  ...  ACKNOWLEDGMENTS Most results presented here were obtained by the authors while they were supported by EPSRC projects M025268 "VADA: Value Added Data Systems" and N023056 "Managing Incomplete Data -New  ...  The first approximation of certain answers to queries on databases with nulls was proposed in [51] , but did not lead to an efficient implementation.  ... 
doi:10.1145/3375395.3387970 dblp:conf/pods/ConsoleGLT20 fatcat:j62xnjuxfbfx7bskzmf6hcg27a

Processing Incomplete k Nearest Neighbor Search

Xiaoye Miao, Yunjun Gao, Gang Chen, Baihua Zheng, Huiyong Cui
2016 IEEE transactions on fuzzy systems  
Furthermore, we propose an approximate algorithm, namely HA, to support approximate IkNN search with improved search efficiency and guaranteed error bound.  ...  In this paper, we systematically study incomplete k nearest neighbor (IkNN) search, which aims at the kNN query for incomplete data.  ...  Consequently, the exact algorithms for kNN queries on this database may not be able to return the answers immediately, since the query is costly on the high dimensional database.  ... 
doi:10.1109/tfuzz.2016.2516562 fatcat:5anog6kydjbnjpjiq4jvcg4lje

TrOWL: Tractable OWL 2 Reasoning Infrastructure [chapter]

Edward Thomas, Jeff Z. Pan, Yuan Ren
2010 Lecture Notes in Computer Science  
Tools exist to reason over these ontologies and to answer queries over them, but there are no large scale infrastructures for storing, reasoning, and querying ontologies on a scale that would be useful  ...  We present the TrOWL infrastructure for transforming, reasoning, and querying OWL2 ontologies which uses novel techniques such as Quality Guaranteed Approximations and Forgetting to achieve this goal.  ...  We would also like to thank Stuart Taylor, Nophadol Jekjantuk and Yuting Zhao at the University of Aberdeen for their helpful discussion and other contributions.  ... 
doi:10.1007/978-3-642-13489-0_38 fatcat:5zf3fzq77rc5hj7n2krlxdbbam

Making SQL Queries Correct on Incomplete Databases

Paolo Guagliardo, Leonid Libkin
2016 Proceedings of the 35th ACM SIGMOD-SIGACT-SIGAI Symposium on Principles of Database Systems - PODS '16  
Having efficiency as its key goal, evaluation of SQL queries disregards the standard notion of correctness on incomplete databases -certain answers -due to its high complexity.  ...  As a result, it may produce answers that are just plain wrong. It was recently shown that SQL evaluation can be modified, at least for first-order queries, to return only correct answers.  ...  Acknowledgments We are grateful to Marco Console for many helpful discussions during the early stages of this work, and to Chris Ré and the anonymous referees for their comments.  ... 
doi:10.1145/2902251.2902297 dblp:conf/pods/GuagliardoL16 fatcat:54iidxhs7vfd7ojt2x3kjqzvya

Towards a logical reconstruction of a theory for locally closed databases

Marc Denecker, Álvaro Cortés-Calabuig, Maurice Bruynooghes, Ofer Arieli
2010 ACM Transactions on Database Systems  
As the complexity of these tasks is unacceptably high, we develop efficient approximate methods for query answering.  ...  At the reasoning level, we study the complexity of, and algorithms for two basic reasoning tasks: computing certain and possible answers to queries and determining whether a database has complete knowledge  ...  Acknowledgment We would like to thank the anonymous reviewers for carefully reading this paper and for many helpful comments. This research was supported by FWO Vlaanderen.Álvaro Cortés-Calabuig was  ... 
doi:10.1145/1806907.1806914 fatcat:hy3qnu7adjgzbjwjdnn4rpxsfm

Uncertainty Annotated Databases - A Lightweight Approach for Approximating Certain Answers (extended version) [article]

Su Feng, Aaron Huber, Boris Glavic, Oliver Kennedy
2019 arXiv   pre-print
UA-DBs are based on incomplete K-relations, which we introduce to generalize the classical set-based notions of incomplete databases and certain answers to a much larger class of data models.  ...  In this paper, we propose Uncertainty Annotated Databases (UA-DBs), which combine an under- and over-approximation of certain answers to achieve the reliability of certain answers, with the performance  ...  Consistent query answering [7, 8] (CQA) is computing certain answers to a query over the incomplete database defined by of all repairs for a database that violates a set of constraints.  ... 
arXiv:1904.00234v1 fatcat:ee2p52rlknbj5ih4auh2yvajfy
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