abstract: This dissertation presents the Temporal Event Query Language (TEQL), a new language for querying event streams. Event Stream Processing enables online querying of streams of events to extract relevant data in a timely manner. TEQL enables querying of interval-based event streams using temporal database operators. Temporal databases and temporal query languages have been a subject of research for more than 30 years and are a natural fit for expressing queries that involve a temporal dimension. However, operators developed in this context cannot be directly applied to event streams. The research extends a preexisting relational framework for event stream processing to support temporal queries. The language features and formal semantic extensions to extend the relational framework are identified. The extended framework supports continuous, step-wise evaluation of temporal queries. The incremental evaluation of TEQL operators is formalized to avoid re-computation of previous results. The research includes the development of a prototype that supports the integrated event and temporal query processing framework, with support for incremental evaluation and materialization of intermediate results. TEQL enables reporting temporal data in the output, direct specification of conditions over timestamps, and specification of temporal relational operators. Through the integration of temporal database operators with event languages, a new class of temporal queries is made possible for querying event streams. New features include semantic aggregation, extraction of temporal patterns using set operators, and a more accurate specification of event co-occurrence. / Dissertation/Thesis / Ph.D. Computer Science 2012

Many modern applications process queries over unbounded streams of data. These applications include tracking financial data from international markets, intrusion detection in networks, monitoring remote sensors, and monitoring patients vital signs. These data streams arrive in real time, are unbounded in length and have unpredictable arrival patterns due to external uncontrollable factors such as network congestion or weather in the case of remote sensors. This thesis presents a novel technique for adapting the execution of stream queries that, to my knowledge, is not present in any other continuous query system to date. This thesis hypothesizes that utilizing a single scheduling algorithm to execute a continuous query, as is employed in other state-of-the-art continuous query systems, is not sufficient because existing scheduling algorithms all have inherent flaws or tradeoffs. Thus, one scheduling algorithm cannot optimally meet an arbitrary set of Quality of Service (QoS) requirements. Therefore, to meet unique features of specific monitoring applications, an adaptive strategy selector guidable by QoS requirements was developed. The adaptive strategy selector monitors the effects of its behavior on its environment through a feedback mechanism, with the aim of exploiting previously beneficial behavior and exploring alternative behavior. The feedback mechanism is guided by qualitatively comparing how well each algorithm has met the QoS requirements. Then the next scheduling algorithm is chosen by spinning a roulette wheel where each candidate is chosen with a probability equal to its performance score. The adaptive algorithm is general, being able to employ any candidate scheduling algorithm and to react to any combination of quality of service preferences. As part of this thesis, the Raindrop system was developed as exploratory test bed in which to conduct an experimental study. In that experimental study, the adaptive algorithm was shown to be effective in outperforming single scheduling algorithms for many QoS combinations and data arrival patterns.

A general XML index can itself be sizable leading to low efficiency. To alleviate this predicament, frequently asked queries can be indexed by a database system. They are referred to as views. Answering queries using materialized views is always cheaper than evaluating over the base data. Traditional techniques solve this problem by considering only a single view. We approach this problem by exploiting the potential relationships of multiple views, which can be used together to answer a given query. Experiments show that significant performance gain can be achieved from multiple views. / A XML query can be decomposed to a sequence of structural joins (e.g., parent/child and ancestor/descendant) and content joins. Thus, structural join optimization is a key to improving join-based evaluation. We optimize structural join with two orthogonal methods: partition-based method exploits the spatial specialities of XML encodings by projecting them on a plane; and location-based method improves structural join by accurately pruning all irrelevant nodes, which cannot produce results. / As XML (eXtensible Markup Language) becomes a universal medium for data exchange over the Internet, efficient XML query processing is now the focus of considerable research and development activities. This thesis describes works toward efficient XML query evaluation and optimization in native XML databases. / XML indexes are widely studied to evaluate XML queries and in particular to accelerate join-based approaches. Index-based approaches outperform join-based approaches (e.g., holistic twig join) if the queries match the index. Existing XML indexes can only support a small set of XML queries because of the varieties in XML query representations. A XML query may involve child-axis only, both child-axis and branches, or additional descendant-or-self-axis but only in the query root. We propose novel indexes to efficiently support a much wider range of XML queries (with /, //, [], *). / Tang, Nan. / "December 2007." / Advisers: Kam-Fei Wong; Jeffrey Xu Yu. / Source: Dissertation Abstracts International, Volume: 69-08, Section: B, page: 4861. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (p. 152-163). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

Abstract not available

Thesis (M.Sc.(Computer Science))--University of Pretoria, 2008. / Includes bibliographical references (leaves 99-116).

Thesis (M.Sc.)--York University, 2008. Graduate Programme in Computer Science. / Typescript. Includes bibliographical references (leaves 147-152). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR38782

Thesis (Ph. D.)--Hong Kong University of Science and Technology, 2004. / Includes bibliographical references (leaves 107-120). Also available in electronic version. Access restricted to campus users.

Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2003. / Includes bibliographical references (leaves 142-147). Also available in electronic version. Access restricted to campus users.

We study three category-theoretic types in the context of functional query languages (typed lambda-calculi extended with additional operations for bulk data processing). The types we study are: / Engineering and Applied Sciences

Darbe nagrinėjama plačiausiai praktikoje paplitusiems duomenų šaltiniams – reliacinėms duomenų bazėms ir XML dokumentams – skirtų užklausų kalbų - SQL, XQuery ir XPath - užklausų struktūra ir savybės. Remiantis analizės rezultatais, sudarytas bendrinis užklausų modelis, kurio paskirtis – padėti formuoti vartotojų užklausas nepriklausomai nuo to, kokiomis technologijomis realizuoti duomenų šaltiniai. Sukurto modelio praktinio taikomumo galimybėms pademonstruoti pateikta juo paremta paieškos sistemos kūrimo metodika. / The thesis presents the analysis of SQL, XQuery and XPath query languages that are intended for the most widely used data sources, namely relational databases and XML documents. Based on the results of the analysis, a generic query model has been developed. The model should serve to help compose user queries without the context of a specific data source implementation technology. The applicability of the model in practice is demonstrated by creating methods for search system development, based on this model.