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Managing data provenance in database

Journal of information and Computational Science 2009年第1期6卷 423-431页

作者： Liu, Xiping Wan, Changxuan Jiang, Tengjiao School of Information Technology Jiangxi University of Finance and Economics Nanchang 330013 China Jiangxi Key Laboratory of Data and Knowledge Engineering Nanchang 330013 China

The paper studies the management problem of data provenance. Firstly, two data models, which enhance the traditional relational model and tree model, are proposed to reveal the basic nature of data provenance. To answer the new challenges to data management posed by data provenance, DBPro, a new database with the ability of managing both data and provenance, is introduced. The storage of data provenance is a core problem in designing DBPro, which is coped with two storage schemes. The comparison between these two storage schemes is also conducted. © 2009 Binary information Press.

关键词： database systems

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Predictable recovery for replication real-time main memory databases using request logs

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Journal of information and Computational Science 2009年第3期6卷 1607-1614页

作者： Liao, Guoqiong Li, Jing School of Information Technology Jiangxi University of Finance and Economics Nanchang 330013 China Jiangxi Key Laboratory of Data and Knowledge Engineering Nanchang 330013 China

Reliable telecommunication applications in future need the supports from replication real-time main memory databases. In order to improve recovery performance and provide predictable recovery, this paper proposes a new recovery method using request logs for the databases. Firstly, the format and correctness of request logs are discussed. Then, a recovery model based on request logs is given. Thirdly, the recovery algorithms for local recovery and resynchronization are provided in details. At last, a formula to estimate denial-of-service time (DoS) is presented for predictable recovery. 1548-7741/ Copyright © 2009 Binary information Press.

关键词： Recovery

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Dynamic programming based top-k aggregate queries in uncertain database

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Journal of information and Computational Science 2009年第3期6卷 1589-1596页

作者： Liu, Dexi School of Information Technology Jiangxi University of Finance and Economics Nanchang 330013 China Jiangxi Key Laboratory of Data and Knowledge Engineering Nanchang 330013 China

A Top-k aggregate query ranks groups of tuples by their aggregate values, sum or average for example, and returns k groups with the highest aggregate values. We propose a dynamic programming based method to process uncertain kRanks aggregate queries in uncertain database, where the number of retrieved tuples and group states generated on these tuples are minimized. Our method has two levels, group state generation and U-x-kRanks query processing. In the former level, group states, which satisfy the properties of x-tuple [13], are generated one after the other according to their aggregate values, while in the latter level, dynamic programming based uncertain x-tuple kRanks query processing [15] are employed to return the answers. Comprehensive experiments on different data sets demonstrate the effectiveness of the proposed solutions. 1548-7741/ Copyright © 2009 Binary information Press.

关键词： Dynamic programming

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A temporal object-oriented RFID data model for object tracking and monitoring in supply chain

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Journal of information and Computational Science 2009年第3期6卷 1505-1513页

作者： Deng, Kun Liao, Guoqiong School of Information Technology Jiangxi University of Finance and Economics Nanchang 330013 China Jiangxi Key Laboratory of Data and Knowledge Engineering Nanchang 330013 China

With the significant advantages of RFID technologies, RFID is being gradually adopted and deployed in a wide area of applications, such as supply chain and logistics. Since RFID data has the characteristics including time-dependent, dynamically changing, large volumes, and carrying implicit semantics, relational data model is not suitable to express and handle RFID data for object tracking and monitoring applications in supply chain and logistics application. This paper first proposes a temporal object-oriented RFID data model based on EPCIS specification, and then the model implementation based on TOODM is introduced in details. In the end, some query examples using TOSQL to track and monitor objects are given. The results shows that our model can express the semantics of RFID data directly and can deal with temporal queries effectively. 1548-7741/ Copyright © 2009 Binary information Press.

关键词： Radio frequency identification (RFID)

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Commit processing of mobile distributed real-time transactions based on mobile agents

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Journal of information and Computational Science 2009年第3期6卷 1627-1634页

作者： Di, Guoqiang Liu, Yaoyao Liao, Guoqiong School of Information Technology Jiangxi University of Finance and Economics Nanchang 330013 China Jiangxi Key Laboratory of Data and Knowledge Engineering Nanchang 330013 China

In mobile computing environment, the features of limited resources, frequent disconnection and long transactions make the success rate of mobile distributed real-time transactions low. Through analyzing the factors impacting the execution of mobile distributed real-time transactions, this paper suggests a mobile distributed real-time transaction model based on mobile agents firstly. Then, a nested advance commit protocol (NACP) is presented, which allows the transactions executing in fixed server to release locks early. The results of performance testing show that NACP can not only effectively increase the successful rate of mobile distributed real-time transactions, but also support disconnection well. 1548-7741/ Copyright © 2009 Binary information Press.

关键词： Mobile agents

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Generating multi-page mirror site from ajax interfaces

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Journal of information and Computational Science 2009年第2期6卷 985-991页

作者： Xia, Tian Key Laboratory of Data Engineering and Knowledge Engineering Renmin University of China Beijing 100872 China School of Information Resource Management Renmin University of China Beijing 100872 China

Ajax is an important approach for improving rich interactivity between web server and end users during Web 2.0 eras. At the same time, AJAX web pages can not be indexed by search engines due to its asynchronous loading. In this paper, we propose a technique for generating the traditional multi-page mirror site from the AJAX based web pages. Firstly, a page state structure to represent any dynamic state of Ajax page is defined, and a states repository is proposed to store the different states. Secondly, each state is fetched from repository and rendered by an embedded browser to get the dynamic DOM, and the click events of candidate clickable elements are fired, then new states are created and stored to repository. Finally, page states are linked and transformed into static HTML files. Experimental results show that mirroring Ajax sites is feasible, though there still have some limitations need to be improved later. Copyright ©2009 Binary information Press.

关键词： Websites

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Incremental computation for MEDIAN cubes in what-if analysis

Incremental computation for MEDIAN cubes in what-if analysis

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Joint International Conference on Advances in data and Web Management, APWeb/WAIM 2009

作者： Xiao, Yanqin Zhang, Yansong Wang, Shan Chen, Hong Key Laboratory of Data Engineering and Knowledge Engineering Renmin University of China MOE Beijing 100872 China School of Information Renmin University of China Beijing 100872 China Computer Center Hebei University Baoding Hebei 071002 China Department of Computer Science Harbin Finance College Harbin 150030 China

ISBN: (纸本)9783642006715

What-if analysis is an important type of DSS analysis processing procedure. It analyzes hypothetical scenarios based on historical data. The data cube view must be updated when the what-if condition is changed. Since source data must be kept in order to compute the new aggregate value when new tuples are inserted or deleted, in what-if analysis, incrementally computing a data cube for holistic aggregation functions is a difficult problem. In this paper, we adopt delta cube strategy and work area technique to incrementally compute data cube for MEDIAN function. The size of work area has important influence on the efficiency of the incremental computing. This paper optimizes the size of work area based on the number and the cardinality of dimension attributes of the cuboid. Performance study shows that our algorithms are effective over large databases. © Springer-Verlag Berlin Heidelberg 2009.

关键词： Geometry

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Efficient incremental computation of CUBE in multiple versions what-if analysis

Efficient incremental computation of CUBE in multiple versio...

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Joint International Conference on Advances in data and Web Management, APWeb/WAIM 2009

ISBN: (纸本)9783642006715

What-if analysis is an important method to analyze the hypothetical scenarios based on the historical data. It provides useful information for the decision- maker. Multiple versions are critical to what-if analysis. In this paper, we analyze the problem of multiple versions data processing and the incremental computation of cubes in what-if analysis, proposing a strategy to process multiple versions of what-if data. Our solution can adopt different data processing methods according to the type of aggregate functions, the efficiency of multiple versions data processing is improved. Furthermore, we proposes an algorithm of incremental computation of CUBE for max(min) function to reduce the access time of fact table, and the experimental results showed that the performance is improved about 10%. © Springer-Verlag Berlin Heidelberg 2009.

关键词： Decision making

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The tradeoff of delta table merging and re-writing algorithms in what-if analysis application

The tradeoff of delta table merging and re-writing algorithm...

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Joint International Conference on Advances in data and Web Management, APWeb/WAIM 2009

作者： Zhang, Yansong Zhang, Yu Xiao, Yanqin Wang, Shan Chen, Hong Key Laboratory of the Ministry of Education for Data Engineering and Knowledge Engineering Renmin University of China Beijing 100872 China School of Information Renmin University of China Beijing 100872 China Department of Computer Science Harbin Finance College Harbin 150030 China Computer Center Hebei University Baoding Hebei 071002 China

ISBN: (纸本)9783642006715

What-if analysis can provide more meaningful information than classical OLAP. Multi-scenario hypothesis based on historical data needs efficient what-if data view support. In general, delta table for what-if analysis is more general than other solutions such as query re-writing prototype of Sesame. Delta table is independent of base table and is more suitable to represent complex hypothetical updates and multi-version hypothetical updates. Due to low efficiency of traditional delta table merging algorithm which is based on set operation, there are few researches focus on delta table merging algorithm but on query re-writing algorithm. By analyzing the difference between what-if query and what-if analysis and improving the delta table merging algorithm, we propose novel algorithms without set operation of difference. Considering the feature of aggregate operations in OLAP analysis, pre-merge algorithm is presented without the generation of what if data view before group-bys in the scenario of SUM, AVERAGE and COUNT function OLAP queries. In our experiments, the pre-merge algorithm greatly improved the efficiency of delta table merging procedure which is close to base group-by statement and superior to the re-writing algorithm. A complete comparison between all candidate delta table merging algorithms and re-writing algorithm with different what-if update conditions of update, deletion, insertion and mixed what-if updates is exhibited in our experiments, the policy of what-if analysis among different types is also discussed. © Springer-Verlag Berlin Heidelberg 2009.

关键词： Merging

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DB Facade: A Web Cache with Improved data Freshness

DB Facade: A Web Cache with Improved Data Freshness

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International Symposium on Electronic Commerce and Security

作者： Xiongpai Qin Xiaoyun Zhou Key Laboratory of Data Engineering and Knowledge Engineering School of Information Renmin University of China Beijing China School of Information and Electrical Engineering China University of Mining and Technology Xuzhou Jiangsu China

Traditional Web database cache techniques have a major disadvantage, namely poor data freshness, because they employ an asynchronous data refresh strategy. A novel Web database cache, DB Facade, is proposed in this paper. DB Facade uses a main memory database to cache result sets of previous queries for subsequent reusing. Updates on backend database system are managed by delta tables, and then propagated to Web database cache in a near real-time manner, hence guarantee the freshness of data. DB Facade off loads query burden from backend database systems, and exploits the power of main memory database system to boost query performance. TPC-W testing result shows that the system's performance increases by about 17 percent.

关键词： database systems System testing Assembly systems Web pages Web server Electronic commerce data security information security Laboratories data engineering

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