Download or read book Answering Queries Using Views Second Edition written by Foto Afrati and published by Springer Nature. This book was released on 2022-05-31 with total page 253 pages. Available in PDF, EPUB and Kindle. Book excerpt: The topic of using views to answer queries has been popular for a few decades now, as it cuts across domains such as query optimization, information integration, data warehousing, website design and, recently, database-as-a-service and data placement in cloud systems. This book assembles foundational work on answering queries using views in a self-contained manner, with an effort to choose material that constitutes the backbone of the research. It presents efficient algorithms and covers the following problems: query containment; rewriting queries using views in various logical languages; equivalent rewritings and maximally contained rewritings; and computing certain answers in the data-integration and data-exchange settings. Query languages that are considered are fragments of SQL, in particular select-project-join queries, also called conjunctive queries (with or without arithmetic comparisons or negation), and aggregate SQL queries. This second edition includes two new chapters that refer to tree-like data and respective query languages. Chapter 8 presents the data model for XML documents and the XPath query language, and Chapter 9 provides a theoretical presentation of tree-like data model and query language where the tuples of a relation share a tree-structured schema for that relation and the query language is a dialect of SQL with evaluation techniques appropriately modified to fit the richer schema.
Download or read book Answering Queries Using Views written by Foto Afrati and published by Springer Nature. This book was released on 2022-11-10 with total page 229 pages. Available in PDF, EPUB and Kindle. Book excerpt: The topic of using views to answer queries has been popular for a few decades now, as it cuts across domains such as query optimization, information integration, data warehousing, website design, and, recently, database-as-a-service and data placement in cloud systems. This book assembles foundational work on answering queries using views in a self-contained manner, with an effort to choose material that constitutes the backbone of the research. It presents efficient algorithms and covers the following problems: query containment; rewriting queries using views in various logical languages; equivalent rewritings and maximally contained rewritings; and computing certain answers in the data-integration and data-exchange settings. Query languages that are considered are fragments of SQL, in particular, select-project-join queries, also called conjunctive queries (with or without arithmetic comparisons or negation), and aggregate SQL queries.
Download or read book Abstraction in Ontology based Data Management written by G. Cima and published by IOS Press. This book was released on 2022-03-08 with total page 270 pages. Available in PDF, EPUB and Kindle. Book excerpt: Effectively documenting data services is a crucial issue in any organization, not only for governing data but also for interoperation purposes. Indeed, in order to fully realize the promises and benefits of a data-driven society, data-driven approaches need to be resilient, transparent, and fully accountable. This book, Abstraction in Ontology-based Data Management, proposes a new approach to automatically associating formal semantic description to data services, thus bringing them into compliance with the FAIR (Findable, Accessible, Interoperable, and Reusable) guiding principles. The approach is founded on the Ontology-based Data Management (OBDM) paradigm, in which a domain ontology is used to provide a high-level semantic layer mapped to the source schema of an organization containing data, thus abstracting from the technical details of the data layer implementation. A formal framework for a novel reasoning task in OBDM, called Abstraction, is introduced in which a data service is assumed to be expressed as a query over the source schema, and the aim is to derive a query over the ontology that semantically describes the given data service best with respect to the underlying OBDM specification. In a general scenario that uses the most popular languages in the OBDM literature, an in-depth complexity analysis of two computational problems associated with the framework is carried out. Also investigated is the problem of expressing abstractions in a non-monotonic query language as well as the impact of adding inequalities. Regarding the latter, the problem of answering queries with inequalities over lightweight ontologies is first studied. Lastly, the author illustrates how the achieved results contribute to new results in the Semantic Web context and in the Relational Database theory. The book will be of interest to all those engaged in Artificial Intelligence and Data Management.
Download or read book Fault Tolerant Distributed Transactions on Blockchain written by Suyash Gupta and published by Springer Nature. This book was released on 2022-06-01 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the introduction of Bitcoin—the first widespread application driven by blockchain—the interest of the public and private sectors in blockchain has skyrocketed. In recent years, blockchain-based fabrics have been used to address challenges in diverse fields such as trade, food production, property rights, identity-management, aid delivery, health care, and fraud prevention. This widespread interest follows from fundamental concepts on which blockchains are built that together embed the notion of trust, upon which blockchains are built. 1. Blockchains provide data transparancy. Data in a blockchain is stored in the form of a ledger, which contains an ordered history of all the transactions. This facilitates oversight and auditing. 2. Blockchains ensure data integrity by using strong cryptographic primitives. This guarantees that transactions accepted by the blockchain are authenticated by its issuer, are immutable, and cannot be repudiated by the issuer. This ensures accountability. 3. Blockchains are decentralized, democratic, and resilient. They use consensus-based replication to decentralize the ledger among many independent participants. Thus, it can operate completely decentralized and does not require trust in a single authority. Additions to the chain are performed by consensus, in which all participants have a democratic voice in maintaining the integrity of the blockchain. Due to the usage of replication and consensus, blockchains are also highly resilient to malicious attacks even when a significant portion of the participants are malicious. It further increases the opportunity for fairness and equity through democratization. These fundamental concepts and the technologies behind them—a generic ledger-based data model, cryptographically ensured data integrity, and consensus-based replication—prove to be a powerful and inspiring combination, a catalyst to promote computational trust. In this book, we present an in-depth study of blockchain, unraveling its revolutionary promise to instill computational trust in society, all carefully tailored to a broad audience including students, researchers, and practitioners. We offer a comprehensive overview of theoretical limitations and practical usability of consensus protocols while examining the diverse landscape of how blockchains are manifested in their permissioned and permissionless forms.
Download or read book Flexible Query Answering Systems 2015 written by Troels Andreasen and published by Springer. This book was released on 2015-10-22 with total page 483 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume contains the papers presented at the Eleventh Flexible Query Answering Systems 2015 (FQAS-2015) held on October 26-28, 2015 in Cracow, Poland. The international conferences on Flexible Query Answering Systems (FQAS) are a series of premier conferences focusing on the key issue in the information society of providing easy, flexible, and intuitive access to information and knowledge to everybody, even people with a very limited computer literacy. In targeting this issue, the Conference draws on several research areas, such as information retrieval, database management, information filtering, knowledge representation, soft computing, management of multimedia information, and human-computer interaction. The Conference provides a unique opportunity for researchers, developers and practitioners to explore new ideas and approaches in a multidisciplinary forum.
Download or read book Database and Expert Systems Applications written by Trevor Bench-Capon and published by Springer. This book was released on 2003-07-31 with total page 1123 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Database and Expert Systems Applications (DEXA) conferences bring together researchers and practitioners from all over the world to exchange ideas, experiences and opinions in a friendly and stimulating environment. The papers are at once a record of what has been achieved and the first steps towards shaping the future of information systems. DEXA covers a broad field, and all aspects of database, knowledge base and related technologies and their applications are represented. Once again there were a good number of submissions: 241 papers were submitted and of these the programme committee selected 103 to be presented. DEXA’99 took place in Florence and was the tenth conference in the series, following events in Vienna, Berlin, Valencia, Prague, Athens, London, Zurich, Toulouse and Vienna. The decade has seen many developments in the areas covered by DEXA, developments in which DEXA has played its part. I would like to express thanks to all the institutions which have actively supported and made possible this conference, namely: • University of Florence, Italy • IDG CNR, Italy • FAW – University of Linz, Austria • Austrian Computer Society • DEXA Association In addition, we must thank all the people who have contributed their time and effort to make the conference possible. Special thanks go to Maria Schweikert (Technical University of Vienna), M. Neubauer and G. Wagner (FAW, University of Linz). We must also thank all the members of the programme committee, whose careful reviews are important to the quality of the conference.
Download or read book Computer Supported Cooperative Work in Design IV written by Weiming Shen and published by Springer. This book was released on 2008-12-18 with total page 688 pages. Available in PDF, EPUB and Kindle. Book excerpt: Design of complex artifacts and systems requires the cooperation of multidisciplinary design teams using multiple sophisticated commercial and non-commercial engine- ing tools such as CAD tools, modeling, simulation and optimization software, en- neering databases, and knowledge-based systems. Individuals or individual groups of multidisciplinary design teams usually work in parallel and independently with various engineering tools, which are located on different sites, often for quite a long period of time. At any moment, individual members may be working on different versions of a design or viewing the design from various perspectives, at different levels of details. In order to meet these requirements, it is necessary to have efficient comput- supported collaborative design systems. These systems should not only automate in- vidual tasks, in the manner of traditional computer-aided engineering tools, but also enable individual members to share information, collaborate, and coordinate their activities within the context of a design project. Based on close international collaboration between the University of Technology of Compiègne in France and the Institute of Computing Technology of the Chinese Ac- emy of Sciences in the early 1990s, a series of international workshops on CSCW in Design started in 1996. In order to facilitate the organization of these workshops, an International Working Group on CSCW in Design (CSCWD) was established and an International Steering Committee was formed in 1998. The series was converted to int- national conferences in 2000 building on the success of the four previous workshops.
Download or read book Flexible Query Answering Systems written by Henrik L. Larsen and published by Springer Science & Business Media. This book was released on 2012-08-27 with total page 617 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume constitutes the proceedings of the Fourth International Conference on Flexible Query Answering Systems, FQAS'2000, held in Warsaw, Poland on October 25 - 28, 2000. The FQAS conference has been the premier conference focusing on one of key issues that the information society faces, namely that of providing easy, flexible, intuitive access to information for everybody. In targeting this issue, the conference draws on several research areas, such as databases, querying, information retrieval, knowledge representation, soft computing, cyberspace, multimedia systems, human-computer interaction, etc. FQAS'2000 has been preceded by the extremely successful FQAS'94, FQAS'96 and FQAS'98 conferences all held in Roskilde, Denmark. The present conference provides a unique opportunity for researchers, developers and practitioners to explore new ideas and approaches in a multidisciplinary forum. As a metaphor for flexible query answering we may consider a human intermediary who has expertise in the topic of the query, and is experienced in identifying the user's information needs and answering the needs from the available information resources. The use of knowledge on relevant contexts, available information resources, etc. , enables the expert to respond rather precisely to the needs, though the query, per se, may be imprecise, incomplete, etc. Thus, a key issue for flexible query answering system is to obtain, maintain, represent, and utilize such knowledge. This comprises domain knowledge and metaknowledge, its representation and organization in ontologies, terminologies, etc.
Download or read book Algorithms for Selecting Views and Indexes to Answer Queries written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In many contexts it is beneà ̄¬ cial to answer database queries using derived data called views. Using views in query answering is relevant in applications in information integration, data warehousing, web-site design, and query optimization. The problem of answering queries using views can be divided into a number of subproblems. The à ̄¬ rst step in the process of view selection is to identify which view can be used to answer queries from the given set. The second step is to determine possible reformulations of the workload queries. The last step is choosing views that can be maintained appropriately and that minimize the processing time of the input query workload. In our work we address the problem of selecting and precomputing indexes and materialized views in a database system, with the goal of improving the processing performance for frequent and important queries. The focus of our work is to develop a unià ̄¬ ed quality-centered view- and index-selection approach, for a range of query, view, and index classes that are typical in practical database systems. To the best of our knowledge, we are the à ̄¬ rst to adopt the solution-quality focus for this generic practical problem setting.
Download or read book Advances in Databases and Information Systems written by Johann Eder and published by Springer Science & Business Media. This book was released on 2005-08-29 with total page 405 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book constitutes the refereed proceedings of the 9th East European Conference on Advances in Databases and Information Systems, ADBIS 2005, held in Tallinn, Estonia, in September 2005. The 27 revised full papers presented together with an invited paper were carefully reviewed and selected from 144 submissions. The papers are organized in topical sections on database theory, database modelling and physical database design, query processing, heterogeneous databases and interoperability, XML and databases, data mining and knowledge discovery, information systems and software engineering, and information systems development.
Download or read book A Top down Approach to Answering Queries Using Views written by Nima Mohajerin and published by . This book was released on 2008 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The problem of answering queries using views is concerned with finding answers to a query using only answers to a set of views. In the context of data integration with LAV approach, this problem translates to finding maximally contained rewriting for a query using a set of views. When both query and views are in conjunctive form, rewritings generated by existing bottom-up algorithms in this context are generally expensive to evaluate. As a result, they often require costly post-processing to improve efficiency of computing the answer tuples. In this dissertation, we propose a top-down approach to the rewriting problem of conjunctive queries. We first present a graph-based analysis of the problem and identify conditions that must be satisfied to ensure maximal containment of rewriting. We then present TreeWise, a novel algorithm that uses our top-down approach to efficiently generate maximally contained rewritings that are generally less expensive to evaluate. Our experiments confirm that TreeWise generally produces better quality rewritings, with a performance comparable to the most efficient of previously proposed algorithms.
Download or read book Notes and Queries written by and published by . This book was released on 1927 with total page 560 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Butterworths Questions and Answers written by Debbie Wilson and published by . This book was released on 2014-01-01 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Flexible Query Answering Systems written by and published by . This book was released on 2000 with total page 640 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Queries written by and published by . This book was released on 1885 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book 500 Plain Answers to Direct Questions on Steam Hot Water Vapor and Vacuum Heating written by Alfred Grant King and published by . This book was released on 1915 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Piano Questions Answered written by Josef Hofmann and published by . This book was released on 1909 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt:
