Proceedings of the 42nd ACM SIGMOD-SIGACT-SIGAI Symposium on Principles of Database Systems最新文献

Bounded Treewidth and the Infinite Core Chase: Complications and Workarounds toward Decidable Querying 有限树宽和无限核心追逐:可决定查询的复杂性和变通方法

Proceedings of the 42nd ACM SIGMOD-SIGACT-SIGAI Symposium on Principles of Database Systems Pub Date : 2023-06-18 DOI: 10.1145/3584372.3588659

Jean-François Baget, M. Mugnier, S. Rudolph

{"title":"Bounded Treewidth and the Infinite Core Chase: Complications and Workarounds toward Decidable Querying","authors":"Jean-François Baget, M. Mugnier, S. Rudolph","doi":"10.1145/3584372.3588659","DOIUrl":"https://doi.org/10.1145/3584372.3588659","url":null,"abstract":"The core chase, a popular algorithm for answering conjunctive queries (CQs) over existential rules, is guaranteed to terminate and compute a finite universal model whenever one exists, leading to the equivalence of the universal-model-based and the chase-based definitions of finite expansion sets (fes) -- a class of rulesets featuring decidable CQ entailment. In case of non-termination, however, it is non-trivial to define a ''result'' of the core chase, due to its non-monotonicity. This causes complications when dealing with advanced decidability criteria based on the existence of (universal) models of finite treewidth. For these, sufficient chase-based conditions have only been established for weaker, monotonic chase variants. This paper investigates the -- prima facie plausible -- hypothesis that the existence of a treewidth-bounded universal model and the existence of a treewidth-bounded core-chase sequence coincide -- which would conveniently entail decidable CQ entailment whenever the latter holds. Perhaps surprisingly, carefully crafted examples show that both directions of this hypothesized correspondence fail. On a positive note, we are still able to define an aggregation scheme for the infinite core chase that preserves treewidth bounds and produces a finitely universal model, i.e., one that satisfies exactly the entailed CQs. This allows us to prove that the existence of a treewidth-bounded core-chase sequence does warrant decidability of CQ entailment (yet, on other grounds than expected). Hence, for the first time, we are able to define a chase-based notion of bounded treewidth sets of rules that subsumes fes.","PeriodicalId":360503,"journal":{"name":"Proceedings of the 42nd ACM SIGMOD-SIGACT-SIGAI Symposium on Principles of Database Systems","volume":"60 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121748244","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: 1

Applications of Sketching and Pathways to Impact 素描的应用和影响途径

Proceedings of the 42nd ACM SIGMOD-SIGACT-SIGAI Symposium on Principles of Database Systems Pub Date : 2023-06-18 DOI: 10.1145/3584372.3589937

Graham Cormode

引用次数: 2

The ACM PODS Alberto O. Mendelzon Test-of-Time Award 2023 ACM PODS Alberto O. Mendelzon测试时间奖2023

Proceedings of the 42nd ACM SIGMOD-SIGACT-SIGAI Symposium on Principles of Database Systems Pub Date : 2023-06-18 DOI: 10.1145/3584372.3590139

M. Arenas, W. Fan, F. Neven

引用次数: 0

Probabilistic Query Evaluation: The Combined FPRAS Landscape 概率查询评估:组合的FPRAS景观

Proceedings of the 42nd ACM SIGMOD-SIGACT-SIGAI Symposium on Principles of Database Systems Pub Date : 2023-06-18 DOI: 10.1145/3584372.3588677

Timothy van Bremen, Kuldeep S. Meel

{"title":"Probabilistic Query Evaluation: The Combined FPRAS Landscape","authors":"Timothy van Bremen, Kuldeep S. Meel","doi":"10.1145/3584372.3588677","DOIUrl":"https://doi.org/10.1145/3584372.3588677","url":null,"abstract":"We consider the problem of computing the probability of a query over a tuple-independent probabilistic database, known as theprobabilistic query evaluation (PQE) problem. The problem is well-known to be #¶-hard in data complexity for conjunctive queries in general, as well as for several subclasses of conjunctive queries. Existing approximation approaches for dealing with hard queries have centred on computing the lineage of the query over the database, which can be intractable for all but the smallest of queries due to the exponential dependence of the lineage size on the query length. In this paper, we take a first step towards bridging this gap, by showing how to construct a fully polynomial-time randomized approximation scheme (FPRAS) for the PQE problem for any class of self-join-free conjunctive queries of bounded hypertree width, that runs in time polynomial inboth the query length and database instance size. An interesting consequence of our result is the existence of classes of queries that are #¶-hard in data complexity to evaluate exactly, yet easy to approximate both in terms of query length and database size.","PeriodicalId":360503,"journal":{"name":"Proceedings of the 42nd ACM SIGMOD-SIGACT-SIGAI Symposium on Principles of Database Systems","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132617168","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: 1

Databases as Graphs: Predictive Queries for Declarative Machine Learning 作为图的数据库:声明性机器学习的预测查询

Proceedings of the 42nd ACM SIGMOD-SIGACT-SIGAI Symposium on Principles of Database Systems Pub Date : 2023-06-18 DOI: 10.1145/3584372.3589939

J. Leskovec

{"title":"Databases as Graphs: Predictive Queries for Declarative Machine Learning","authors":"J. Leskovec","doi":"10.1145/3584372.3589939","DOIUrl":"https://doi.org/10.1145/3584372.3589939","url":null,"abstract":"The era of intelligent systems and applications is here and AI has been disrupting science and industry. The speed of change has been breathtaking. However, building AI-based solutions is hard, training Machine Learning models and putting them in production takes highly-skilled teams months if not years. There is a real need to drastically simplify machine learning workflow and bring AI closer to users, and make it accessible to a wide range of audiences. In this talk, I present Kumo, a no-code machine learning platform that enables data scientists to solve a wide range of machine learning problems over relational tables in a database in a simple declarative way. Kumo provides a SQL-like Predictive Query language that allows for declarative specification of machine learning problems in a wide array of applications from sales and marketing to customer retention and recommender systems. The key insight in Kumo is that relational schema can be represented as a heterogeneous hypergraph. Such graphs are emerging as an abstraction to represent complex data and Deep Graph Neural Networks (GNN) can then be used to learn optimal feature representation for any entity of interest. Automatic learning to encode graph structure into low-dimensional embeddings brings several benefits: (1) automatic learning from the entire data spread across multiple relational tables (2) no manual feature engineering as the system learns optimal embeddings; (3) state-of-the-art predictive performance. Building such a distributed system for GNN training and inference poses several interesting algorithmic and data processing challenges, which we address by innovative machine learning methods and careful algorithm/architecture codesign. Kumo has already been successfully deployed at several major companies.","PeriodicalId":360503,"journal":{"name":"Proceedings of the 42nd ACM SIGMOD-SIGACT-SIGAI Symposium on Principles of Database Systems","volume":"119 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124575239","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: 2

Indexing for Keyword Search with Structured Constraints 结构化约束下关键字搜索的索引

Proceedings of the 42nd ACM SIGMOD-SIGACT-SIGAI Symposium on Principles of Database Systems Pub Date : 2023-06-18 DOI: 10.1145/3584372.3588663

Shangqi Lu, Yufei Tao

引用次数: 0

Guaranteeing the Õ(AGM/OUT) Runtime for Uniform Sampling and Size Estimation over Joins 保证Õ(AGM/OUT)运行时间为统一采样和连接大小估计

Proceedings of the 42nd ACM SIGMOD-SIGACT-SIGAI Symposium on Principles of Database Systems Pub Date : 2023-06-18 DOI: 10.1145/3584372.3588676

Kyoungmin Kim, J. Ha, G. Fletcher, Wook-Shin Han

引用次数: 1

Allocating Isolation Levels to Transactions in a Multiversion Setting 在多版本设置中为事务分配隔离级别

Proceedings of the 42nd ACM SIGMOD-SIGACT-SIGAI Symposium on Principles of Database Systems Pub Date : 2023-06-18 DOI: 10.1145/3584372.3588672

Brecht Vandevoort, Bas Ketsman, F. Neven

{"title":"Allocating Isolation Levels to Transactions in a Multiversion Setting","authors":"Brecht Vandevoort, Bas Ketsman, F. Neven","doi":"10.1145/3584372.3588672","DOIUrl":"https://doi.org/10.1145/3584372.3588672","url":null,"abstract":"A serializable concurrency control mechanism ensures consistency for OLTP systems at the expense of a reduced transaction throughput. A DBMS therefore usually offers the possibility to allocate lower isolation levels for some transactions when it is safe to do so. However, such trading of consistency for efficiency does not come with any safety guarantees. In this paper, we study the mixed robustness problem which asks whether, for a given set of transactions and a given allocation of isolation levels, every possible interleaved execution of those transactions that is allowed under the provided allocation is always serializable. That is, whether the given allocation is indeed safe. While robustness has already been studied in the literature for the homogeneous setting where all transactions are allocated the same isolation level, the heterogeneous setting that we consider in this paper, despite its practical relevance, has largely been ignored. We focus on multiversion concurrency control and consider the isolation levels that are available in Postgres and Oracle: read committed (RC), snapshot isolation (SI) and serializable snapshot isolation (SSI). We show that the mixed robustness problem can be decided in polynomial time. In addition, we provide a polynomial time algorithm for computing the optimal robust allocation for a given set of transactions, prioritizing lower over higher isolation levels. The present results therefore establish the groundwork to automate isolation level allocation within existing databases supporting multiversion concurrency control.","PeriodicalId":360503,"journal":{"name":"Proceedings of the 42nd ACM SIGMOD-SIGACT-SIGAI Symposium on Principles of Database Systems","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121674633","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: 2

Distributed Consistency Beyond Queries 超越查询的分布式一致性

Proceedings of the 42nd ACM SIGMOD-SIGACT-SIGAI Symposium on Principles of Database Systems Pub Date : 2023-06-18 DOI: 10.1145/3584372.3588657

Tim Baccaert, Bas Ketsman

{"title":"Distributed Consistency Beyond Queries","authors":"Tim Baccaert, Bas Ketsman","doi":"10.1145/3584372.3588657","DOIUrl":"https://doi.org/10.1145/3584372.3588657","url":null,"abstract":"Programming asynchronous distributed systems is a challenging task in which consistency is often achieved by use of expensive coordination protocols like Paxos and 2PC. The CALM theorem, first conjectured by Hellerstein, is one of the first results to challenge this practice by stating that a problem can have a consistent, coordination-free distributed implementation if (and only if) the problem is monotonic. This result was proven for queries and shown to extend beyond monotonic (yet monotonic-like) queries for data systems having specific knowledge about the partitioning of data over the network. In this article, we extend the latter results in several ways. We consider problems that can be modeled as mappings from distributed instances to distributed instances, enabling insights into a much broader range of problems than queries. Furthermore, our model can express arbitrary system configurations, allowing us to reason about the expressiveness of any particular distributed system and thereby revealing a nuanced gradient of problems with increasing coordination-needs. Finally, we apply our model to a recent question about the expressiveness of coordination-free queries, raised by Hellerstein and Alvaro.","PeriodicalId":360503,"journal":{"name":"Proceedings of the 42nd ACM SIGMOD-SIGACT-SIGAI Symposium on Principles of Database Systems","volume":"105 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121772677","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: 0

SQL Nulls and Two-Valued Logic SQL空值和二值逻辑

Proceedings of the 42nd ACM SIGMOD-SIGACT-SIGAI Symposium on Principles of Database Systems Pub Date : 2023-06-18 DOI: 10.1145/3584372.3588661

L. Libkin, L. Peterfreund

{"title":"SQL Nulls and Two-Valued Logic","authors":"L. Libkin, L. Peterfreund","doi":"10.1145/3584372.3588661","DOIUrl":"https://doi.org/10.1145/3584372.3588661","url":null,"abstract":"The design of SQL is based on a three-valued logic (3VL), rather than the familiar two-valued Boolean logic (2VL). In addition totrue andfalse, 3VL addsunknown to handle nulls. Viewed as indispensable for SQL expressiveness, it is often criticized for unintuitive behavior of queries and for being a source of programmer mistakes. We show that, contrary to the widely held view, SQL could have been designed based on 2VL, without any loss of expressiveness. Similarly to SQL's WHERE clause, which only keeps true tuples, we conflate false and unknown for conditions involving nulls to obtain an equally expressive 2VL-based version of SQL. This applies to the core of the 1999 SQL Standard. Queries written under the 2VL semantics can be efficiently translated into the 3VL SQL and thus executed on any existing RDBMS. We show that 2VL enables additional optimizations. To gauge its applicability, we establish criteria under which 2VL and 3VL semantics coincide, and analyze common benchmarks such as TPC-H and TPC-DS to show that most of their queries are such. For queries that behave differently under 2VL and 3VL, we undertake a user study to show a consistent preference for the 2VL semantics.","PeriodicalId":360503,"journal":{"name":"Proceedings of the 42nd ACM SIGMOD-SIGACT-SIGAI Symposium on Principles of Database Systems","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130554582","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: 1