Database theory-- ICDT : International Conference ... proceedings. International Conference on Database Theory最新文献_第10页

Front Matter, Table of Contents, Preface, Conference Organization, List of Authors 前文，目录，序言，会议组织，作者名单

Database theory-- ICDT : International Conference ... proceedings. International Conference on Database Theory Pub Date : 2017-01-01 DOI: 10.4230/LIPIcs.ICDT.2017.0

Michael Benedikt, G. Orsi

引用次数: 0

k-Regret Minimizing Set: Efficient Algorithms and Hardness k-遗憾最小化集:高效算法和硬度

Database theory-- ICDT : International Conference ... proceedings. International Conference on Database Theory Pub Date : 2017-01-01 DOI: 10.4230/LIPIcs.ICDT.2017.11

Wei Cao, J. Li, Haitao Wang, Kangning Wang, Ruosong Wang, R. C. Wong, Wei Zhan

{"title":"k-Regret Minimizing Set: Efficient Algorithms and Hardness","authors":"Wei Cao, J. Li, Haitao Wang, Kangning Wang, Ruosong Wang, R. C. Wong, Wei Zhan","doi":"10.4230/LIPIcs.ICDT.2017.11","DOIUrl":"https://doi.org/10.4230/LIPIcs.ICDT.2017.11","url":null,"abstract":"We study the k-regret minimizing query (k-RMS), which is a useful operator for supporting multi-criteria decision-making. Given two integers k and r, a k-RMS returns r tuples from the database which minimize the k-regret ratio, defined as one minus the worst ratio between the k-th maximum utility score among all tuples in the database and the maximum utility score of the r tuples returned. A solution set contains only r tuples, enjoying the benefits of both top-k queries and skyline queries. Proposed in 2012, the query has been studied extensively in recent years. In this paper, we advance the theory and the practice of k-RMS in the following aspects. First, we develop efficient algorithms for k-RMS (and its decision version) when the dimensionality is 2. The running time of our algorithms outperforms those of previous ones. Second, we show that k-RMS is NP-hard even when the dimensionality is 3. This provides a complete characterization of the complexity of k-RMS, and answers an open question in previous studies. In addition, we present approximation algorithms for the problem when the dimensionality is 3 or larger.","PeriodicalId":90482,"journal":{"name":"Database theory-- ICDT : International Conference ... proceedings. International Conference on Database Theory","volume":"28 1","pages":"11:1-11:19"},"PeriodicalIF":0.0,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81800461","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 32

m-tables: Representing Missing Data m-tables:表示丢失的数据

Database theory-- ICDT : International Conference ... proceedings. International Conference on Database Theory Pub Date : 2017-01-01 DOI: 10.4230/LIPIcs.ICDT.2017.21

Bruhathi Sundarmurthy, Paraschos Koutris, Willis Lang, J. Naughton, V. Tannen

引用次数: 22

Compression of Unordered XML Trees 无序XML树的压缩

Database theory-- ICDT : International Conference ... proceedings. International Conference on Database Theory Pub Date : 2017-01-01 DOI: 10.4230/LIPIcs.ICDT.2017.18

Markus Lohrey, S. Maneth, C. Reh

引用次数: 9

GYM: A Multiround Distributed Join Algorithm GYM:一种多轮分布式连接算法

Database theory-- ICDT : International Conference ... proceedings. International Conference on Database Theory Pub Date : 2017-01-01 DOI: 10.4230/LIPIcs.ICDT.2017.4

F. Afrati, Manas R. Joglekar, C. Ré, S. Salihoglu, J. Ullman

{"title":"GYM: A Multiround Distributed Join Algorithm","authors":"F. Afrati, Manas R. Joglekar, C. Ré, S. Salihoglu, J. Ullman","doi":"10.4230/LIPIcs.ICDT.2017.4","DOIUrl":"https://doi.org/10.4230/LIPIcs.ICDT.2017.4","url":null,"abstract":"Multiround algorithms are now commonly used in distributed data processing systems, yet the extent to which algorithms can benefit from running more rounds is not well understood. This paper answers this question for several rounds for the problem of computing the equijoin of n relations. Given any query Q with width w, intersection width iw, input size IN, output size OUT, and a cluster of machines with M=Omega(IN frac{1}{epsilon}) memory available per machine, where epsilon > 1 and w ge 1 are constants, we show that: 1. Q can be computed in O(n) rounds with O(n(INw + OUT)2/M) communication cost with high probability. Q can be computed in O(log(n)) rounds with O(n(INmax(w, 3iw) + OUT)2/M) communication cost with high probability. Intersection width is a new notion we introduce for queries and generalized hypertree decompositions (GHDs) of queries that captures how connected the adjacent components of the GHDs are. We achieve our first result by introducing a distributed and generalized version of Yannakakis's algorithm, called GYM. GYM takes as input any GHD of Q with width w and depth d, and computes Q in O(d + log(n)) rounds and O(n (INw + OUT)2/M) communication cost. We achieve our second result by showing how to construct GHDs of Q with width max(w, 3iw) and depth O(log(n)). We describe another technique to construct GHDs with longer widths and lower depths, demonstrating other tradeoffs one can make between communication and the number of rounds.","PeriodicalId":90482,"journal":{"name":"Database theory-- ICDT : International Conference ... proceedings. International Conference on Database Theory","volume":"46 1","pages":"4:1-4:18"},"PeriodicalIF":0.0,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84297694","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 28

Combined Tractability of Query Evaluation via Tree Automata and Cycluits (Extended Version) 基于树自动机和循环的查询求值组合可跟踪性(扩展版)

Database theory-- ICDT : International Conference ... proceedings. International Conference on Database Theory Pub Date : 2016-12-13 DOI: 10.4230/LIPIcs.ICDT.2017.6

Antoine Amarilli, P. Bourhis, Mikaël Monet, P. Senellart

引用次数: 8

The complexity of reverse engineering problems for conjunctive queries 联合查询的逆向工程问题的复杂性

Database theory-- ICDT : International Conference ... proceedings. International Conference on Database Theory Pub Date : 2016-06-03 DOI: 10.4230/LIPIcs.ICDT.2017.7

P. Barceló, M. Romero

{"title":"The complexity of reverse engineering problems for conjunctive queries","authors":"P. Barceló, M. Romero","doi":"10.4230/LIPIcs.ICDT.2017.7","DOIUrl":"https://doi.org/10.4230/LIPIcs.ICDT.2017.7","url":null,"abstract":"Reverse engineering problems for conjunctive queries (CQs), such as query by example (QBE) or definability, take a set of user examples and convert them into an explanatory CQ. Despite their importance, the complexity of these problems is prohibitively high (coNEXPTIME-complete). We isolate their two main sources of complexity and propose relaxations of them that reduce the complexity while having meaningful theoretical interpretations. The first relaxation is based on the idea of using existential pebble games for approximating homomorphism tests. We show that this characterizes QBE/definability for CQs up to treewidth $k$, while reducing the complexity to EXPTIME. As a side result, we obtain that the complexity of the QBE/definability problems for CQs of treewidth $k$ is EXPTIME-complete for each $k geq 1$. The second relaxation is based on the idea of \"desynchronizing\" direct products, which characterizes QBE/definability for unions of CQs and reduces the complexity to coNP. The combination of these two relaxations yields tractability for QBE and characterizes it in terms of unions of CQs of treewidth at most $k$. We also study the complexity of these problems for conjunctive regular path queries over graph databases, showing them to be no more difficult than for CQs.","PeriodicalId":90482,"journal":{"name":"Database theory-- ICDT : International Conference ... proceedings. International Conference on Database Theory","volume":"8 1 1","pages":"7:1-7:17"},"PeriodicalIF":0.0,"publicationDate":"2016-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78645723","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 42

Filtering With the Crowd: CrowdScreen Revisited 与人群一起过滤:重新审视CrowdScreen

Database theory-- ICDT : International Conference ... proceedings. International Conference on Database Theory Pub Date : 2016-03-15 DOI: 10.4230/LIPIcs.ICDT.2016.12

B. Groz, Ezra Levin, I. Meilijson, T. Milo

{"title":"Filtering With the Crowd: CrowdScreen Revisited","authors":"B. Groz, Ezra Levin, I. Meilijson, T. Milo","doi":"10.4230/LIPIcs.ICDT.2016.12","DOIUrl":"https://doi.org/10.4230/LIPIcs.ICDT.2016.12","url":null,"abstract":"Filtering a set of items, based on a set of properties that can be verified by humans, is a common application of CrowdSourcing. When the workers are error-prone, each item is presented to multiple users, to limit the probability of misclassification. Since the Crowd is a relatively expensive resource, minimizing the number of questions per item may naturally result in big savings. Several algorithms to address this minimization problem have been presented in the CrowdScreen framework by Parameswaran et al. However, those algorithms do not scale well and therefore cannot be used in scenarios where high accuracy is required in spite of high user error rates. The goal of this paper is thus to devise algorithms that can cope with such situations. To achieve this, we provide new theoretical insights to the problem, then use them to develop a new efficient algorithm. We also propose novel optimizations for the algorithms of CrowdScreen that improve their scalability. We complement our theoretical study by an experimental evaluation of the algorithms on a large set of synthetic parameters as well as real-life crowdsourcing scenarios, demonstrating the advantages of our solution.","PeriodicalId":90482,"journal":{"name":"Database theory-- ICDT : International Conference ... proceedings. International Conference on Database Theory","volume":"14 1","pages":"12:1-12:18"},"PeriodicalIF":0.0,"publicationDate":"2016-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86083813","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 4

A Formal Study of Collaborative Access Control in Distributed Datalog 分布式数据中协同访问控制的形式化研究

Database theory-- ICDT : International Conference ... proceedings. International Conference on Database Theory Pub Date : 2016-03-15 DOI: 10.4230/LIPIcs.ICDT.2016.10

S. Abiteboul, P. Bourhis, V. Vianu

{"title":"A Formal Study of Collaborative Access Control in Distributed Datalog","authors":"S. Abiteboul, P. Bourhis, V. Vianu","doi":"10.4230/LIPIcs.ICDT.2016.10","DOIUrl":"https://doi.org/10.4230/LIPIcs.ICDT.2016.10","url":null,"abstract":"We formalize and study a declaratively specified collaborative access control mechanism for data dissemination in a distributed environment. Data dissemination is specified using distributed datalog. Access control is also defined by datalog-style rules, at the relation level for extensional relations, and at the tuple level for intensional ones, based on the derivation of tuples. The model also includes a mechanism for \" declassifying \" data, that allows circumventing overly restrictive access control. We consider the complexity of determining whether a peer is allowed to access a given fact, and address the problem of achieving the goal of disseminating certain information under some access control policy. We also investigate the problem of information leakage, which occurs when a peer is able to infer facts to which the peer is not allowed access by the policy. Finally, we consider access control extended to facts equipped with provenance information, motivated by the many applications where such information is required. We provide semantics for access control with provenance, and establish the complexity of determining whether a peer may access a given fact together with its provenance. This work is motivated by the access control of the Webdamlog system, whose core features it formalizes.","PeriodicalId":90482,"journal":{"name":"Database theory-- ICDT : International Conference ... proceedings. International Conference on Database Theory","volume":"99 1","pages":"10:1-10:17"},"PeriodicalIF":0.0,"publicationDate":"2016-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81187938","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 7

Worst-Case Optimal Algorithms for Parallel Query Processing 并行查询处理的最坏情况最优算法

Database theory-- ICDT : International Conference ... proceedings. International Conference on Database Theory Pub Date : 2016-03-01 DOI: 10.4230/LIPIcs.ICDT.2016.8

P. Beame, Paraschos Koutris, Dan Suciu

{"title":"Worst-Case Optimal Algorithms for Parallel Query Processing","authors":"P. Beame, Paraschos Koutris, Dan Suciu","doi":"10.4230/LIPIcs.ICDT.2016.8","DOIUrl":"https://doi.org/10.4230/LIPIcs.ICDT.2016.8","url":null,"abstract":"In this paper, we study the communication complexity for the problem of computing a conjunctive query on a large database in a parallel setting with $p$ servers. In contrast to previous work, where upper and lower bounds on the communication were specified for particular structures of data (either data without skew, or data with specific types of skew), in this work we focus on worst-case analysis of the communication cost. The goal is to find worst-case optimal parallel algorithms, similar to the work of [18] for sequential algorithms. \u0000We first show that for a single round we can obtain an optimal worst-case algorithm. The optimal load for a conjunctive query $q$ when all relations have size equal to $M$ is $O(M/p^{1/psi^*})$, where $psi^*$ is a new query-related quantity called the edge quasi-packing number, which is different from both the edge packing number and edge cover number of the query hypergraph. For multiple rounds, we present algorithms that are optimal for several classes of queries. Finally, we show a surprising connection to the external memory model, which allows us to translate parallel algorithms to external memory algorithms. This technique allows us to recover (within a polylogarithmic factor) several recent results on the I/O complexity for computing join queries, and also obtain optimal algorithms for other classes of queries.","PeriodicalId":90482,"journal":{"name":"Database theory-- ICDT : International Conference ... proceedings. International Conference on Database Theory","volume":"82 1","pages":"8:1-8:18"},"PeriodicalIF":0.0,"publicationDate":"2016-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77126567","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 57