Proceedings of the 35th ACM SIGMOD-SIGACT-SIGAI Symposium on Principles of Database Systems最新文献

{"title":"Proceedings of the 35th ACM SIGMOD-SIGACT-SIGAI Symposium on Principles of Database Systems","authors":"Emanuel Sallinger, J. V. D. Bussche, Floris Geerts","doi":"10.1145/2902251","DOIUrl":"https://doi.org/10.1145/2902251","url":null,"abstract":"This year's symposium continues this tradition and continues to explicitly invite for submission papers providing original, substantial contributions in one or more of the following categories: a) Deep theoretical exploration of topical areas central to data management; b) New formal frameworks that aim at providing the basis for deeper theoretical investigation of important emerging issues in data management; and c) Validation of theoretical approaches from the lens of practical applicability in data management. Apart from validating the practical applicability of existing theoretical approaches, submissions in this category are expected to provide a clear message to the database theory community as to which aspects need further theoretical investigation, based on the experimental findings. \u0000 \u0000This volume contains the proceedings of PODS 2017, which include a paper for the keynote address by Susan Davidson (University of Pennsylvania, USA), abstracts based on two invited tutorials by Lise Getoor (University of California Santa Cruz, USA) and Dan Suciu (University of Washington, USA), and 29 contributions that were selected by the Program Committee for presentation at the symposium. \u0000 \u0000In addition, this volume also contains papers from our two \"Gems of PODS\" speakers, Alon Halevy (Recruit Institute of Technology, USA) and Val Tannen (University of Pennsylvania, USA). The Gems of PODS is an event, started in 2016, where the goal is to promote understanding of past seminal PODS results to the general audience. The Gems of PODS papers were selected by the Gems of PODS committee consisting of Floris Geerts (chair), Christoph Koch and Pierre Senellart. \u0000 \u0000This year, PODS continued with two submission cycles that were introduced two years ago. The first cycle allowed for the possibility for papers to be revised and resubmitted. For the first cycle, 28 papers were submitted, 3 of which were directly selected for inclusion in the proceedings, and 13 were invited for a resubmission after a revision. The quality of most of the revised papers increased substantially with respect to the first submission, and 9 of 13 revised papers were selected for the proceedings. For the second cycle, 73 papers were submitted, 17 of which were selected, resulting in 29 papers selected overall from a total number of 101 submissions. \u0000 \u0000With respect to the three categories mentioned above, of the 101 submissions (resp., 29 accepted papers), 66 (resp., 22) were classified by the authors in category (a), 9 (resp., 1) in category (b), 2 (resp., 0) in category (c), 14 (resp., 4) in categories (a)&(b), 7 (resp., 1) in categories (a)&(c), and 3 (resp., 1) in categories (b)&(c). The authors were asked to select the most appropriate categories for their papers at submission time. \u0000 \u0000An important task for the Program Committee has been the selection of the PODS 2017 Best Paper Award. The committee selected the paper \u0000\"Dichotomies in Ontology-Mediated Querying with the Guarded Fragmen","PeriodicalId":158471,"journal":{"name":"Proceedings of the 35th ACM SIGMOD-SIGACT-SIGAI Symposium on Principles of Database Systems","volume":"72 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117115147","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}

{"title":"Minimization of Tree Pattern Queries","authors":"Wojciech Czerwinski, W. Martens, Matthias Niewerth, P. Parys","doi":"10.1145/2902251.2902295","DOIUrl":"https://doi.org/10.1145/2902251.2902295","url":null,"abstract":"We investigate minimization of tree pattern queries that use the child relation, descendant relation, node labels, and wildcards. We prove that minimization for such tree patterns is Sigma2P-complete and thus solve a problem first attacked by Flesca, Furfaro, and Masciari in 2003. We first provide an example that shows that tree patterns cannot be minimized by deleting nodes. This example shows that the M-NR conjecture, which states that minimality of tree patterns is equivalent to their nonredundancy, is false. We then show how the example can be turned into a gadget that allows us to prove Sigma2P-completeness.","PeriodicalId":158471,"journal":{"name":"Proceedings of the 35th ACM SIGMOD-SIGACT-SIGAI Symposium on Principles of Database Systems","volume":"76 2-3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116581680","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}

{"title":"A Theory of Regular Queries","authors":"Moshe Y. Vardi","doi":"10.1145/2902251.2902305","DOIUrl":"https://doi.org/10.1145/2902251.2902305","url":null,"abstract":"A major theme in relational database theory is navigating the tradeoff between expressiveness and tractability for query languages, where the query-containment problem is considered a benchmark of tractability. The query class UCQ, consisting off unions of conjunctive queries, is a fragment of first-order logic that has a decidable query containment problem, but its expressiveness is limited. Extending UCQ with recursion yields Datalog, an expressive query language that has been studied extensively and has recently become popular in application areas such as declarative networking. Unfortunately, Datalog has an undecidable query containment problem. Identifying a fragment of Datalog that is expressive enough for applications but has a decidable query-containment problem has been an open problem for several years. In the area of graph databases, there has been a similar search for a query language that combines expressiveness and tractability. Because of the need to navigate along graph paths of unspecified length, transitive closure has been considered a fundamental operation. Query classes of increasing complexity -- using the operations of disjunction, conjunction, projection, and transitive closure -- have been studied, but the classes lacked natural closure properties. The class RQ of regular queries has emerged only recently as a natural query class that is closed under all of its operations and has a decidable query-containment problem. RQ turned out to be a fragment of Datalog where recursion can be used only to express transitive closure. Furthermore, it turns out that applying this idea to Datalog, that is, restricting recursion to the expression of transitive closure, does yield the long-sought goal -- an expressive fragment of Datalog with a decidable query-optimization problem.","PeriodicalId":158471,"journal":{"name":"Proceedings of the 35th ACM SIGMOD-SIGACT-SIGAI Symposium on Principles of Database Systems","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134111266","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}

{"title":"Bounded Query Rewriting Using Views","authors":"Yang Cao, W. Fan, Floris Geerts, Ping Lu","doi":"10.1145/2902251.2902294","DOIUrl":"https://doi.org/10.1145/2902251.2902294","url":null,"abstract":"A query Q has a bounded rewriting using a set of views if there exists a query Q' expressed in the same language as Q, such that given a dataset D, Q(D) can be computed by Q' that accesses only cached views and a small fraction DQ of D. We consider datasets D that satisfy a set of access constraints, a combination of cardinality constraints and associated indices, such that the size |DQ| of DQ and the time to identify DQ are independent of |D|, no matter how big D is. This paper studies the problem for deciding whether a query has a bounded rewriting given a set V of views and a set A of access constraints. We establish the complexity of the problem for various query languages, from Σ3p-complete for conjunctive queries (CQ), to undecidable for relational algebra (FO). We show that the intractability for CQ is rather robust even for acyclic CQ with fixed V and A, and characterize when the problem is in PTIME. To make practical use of bounded rewriting, we provide an effective syntax for FO queries that have a bounded rewriting. The syntax characterizes a core subclass of such queries without sacrificing the expressive power, and can be checked in PTIME.","PeriodicalId":158471,"journal":{"name":"Proceedings of the 35th ACM SIGMOD-SIGACT-SIGAI Symposium on Principles of Database Systems","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115375047","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}

{"title":"Session details: Session 5: Data Streams and Privacy","authors":"Graham Comcorde","doi":"10.1145/3252642","DOIUrl":"https://doi.org/10.1145/3252642","url":null,"abstract":"","PeriodicalId":158471,"journal":{"name":"Proceedings of the 35th ACM SIGMOD-SIGACT-SIGAI Symposium on Principles of Database Systems","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123546822","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}

{"title":"Fast Algorithms for Parsing Sequences of Parentheses with Few Errors","authors":"A. Backurs, Krzysztof Onak","doi":"10.1145/2902251.2902304","DOIUrl":"https://doi.org/10.1145/2902251.2902304","url":null,"abstract":"We consider the problem of fixing sequences of unbalanced parentheses. A classic algorithm based on dynamic programming computes the optimum sequence of edits required to solve the problem in cubic time. We show the first algorithm that runs in linear time when the number of necessary edits is small. More precisely, our algorithm runs in O(n) + dO(1) time, where n is the length of the sequence to be fixed and d is the minimum number of edits. The problem of fixing parentheses sequences is related to the task of repairing semi-structured documents such as XML and JSON.","PeriodicalId":158471,"journal":{"name":"Proceedings of the 35th ACM SIGMOD-SIGACT-SIGAI Symposium on Principles of Database Systems","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126898674","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}

{"title":"Logical Aspects of Massively Parallel and Distributed Systems","authors":"F. Neven","doi":"10.1145/2902251.2902307","DOIUrl":"https://doi.org/10.1145/2902251.2902307","url":null,"abstract":"Database research has witnessed a renewed interest for data processing in distributed and parallel settings. While distributed and parallel data management systems have been around for quite some time, it is the rise of cloud computing and the advent of Big Data that presents the community with new challenges. This paper highlights recent research concerning the logical foundations of massively parallel and distributed systems. The first part of the paper concerns massively parallel systems where computation proceeds in a number of synchronized rounds. Here, the focus is on evaluation algorithms for conjunctive queries as well as on reasoning about correctness and optimization of such algorithms. The second part of the paper addresses a distributed asynchronous setting where eventual consistency comes into play. Here, the focus is on coordination-free computation and its relationship to logical monotonicity and Datalog programs.","PeriodicalId":158471,"journal":{"name":"Proceedings of the 35th ACM SIGMOD-SIGACT-SIGAI Symposium on Principles of Database Systems","volume":"172 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122992897","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}

{"title":"Session details: Session 6: Algorithms and Data Structures","authors":"K. Yi","doi":"10.1145/3252643","DOIUrl":"https://doi.org/10.1145/3252643","url":null,"abstract":"","PeriodicalId":158471,"journal":{"name":"Proceedings of the 35th ACM SIGMOD-SIGACT-SIGAI Symposium on Principles of Database Systems","volume":"408 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116691786","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}

{"title":"Making SQL Queries Correct on Incomplete Databases: A Feasibility Study","authors":"P. Guagliardo, L. Libkin","doi":"10.1145/2902251.2902297","DOIUrl":"https://doi.org/10.1145/2902251.2902297","url":null,"abstract":"Multiple issues with SQL's handling of nulls have been well documented. 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. But while these modifications came with good theoretical complexity bounds, they have not been tested in practice. The goals of this proof-of-concept paper are to understand whether wrong answers can be produced by SQL queries in real-world scenarios, and whether proposed techniques for avoiding them can be made practically feasible. We use the TPC-H benchmark, and show that for some typical queries involving negation, wrong answers are very common. On the other hand, existing solutions for fixing the problem do not work in practice at all. By analyzing the reasons for this, we come up with a new modified way of rewriting SQL queries that restores correctness. We conduct experiments which show the feasibility of our solution: the small price tag it imposes can be often tolerated to ensure correct results, and we do not miss correct answers that the usual SQL evaluation produces. The overall conclusion is that correct evaluation can be realistically achieved in the presence of nulls, at least for the SQL fragment that corresponds to first-order queries.","PeriodicalId":158471,"journal":{"name":"Proceedings of the 35th ACM SIGMOD-SIGACT-SIGAI Symposium on Principles of Database Systems","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131393816","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}

{"title":"Session details: PODS Award talks + 1 regular paper","authors":"Jan Van den Bussche","doi":"10.1145/3252634","DOIUrl":"https://doi.org/10.1145/3252634","url":null,"abstract":"","PeriodicalId":158471,"journal":{"name":"Proceedings of the 35th ACM SIGMOD-SIGACT-SIGAI Symposium on Principles of Database Systems","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127661605","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}