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1.
在Web应用中,以XML为格式的信息查询通常会受到网络传输速度有限等因素的影响。为了减少XML的物化视图与其数据源之间的一致性维护中所需的网络数据传输开销,提出了一种面向远程的XML物化视图增量维护方法和系统框架。这种方法根据多用户的查询请求和数据源更新信息,生成视图维护程序代码,以程序代码的网络迁移代替XML视图的重复查询,有效地减少了网络数据传输量。介绍了物化视图增量维护的基本原理、系统框架以及设计实现思路。最后通过性能测试,说明这种增量维护系统能够有效地减少传输开销。  相似文献   

2.
在试验任务中引入XML文档数据接口,一方面提高了远程数据查询分析的效率,另一方面也产生了XML物化视图的维护带来的高系统开销的问题.针对该问题,采用XML物化视图远程增量维护的方法,通过系统原型设计、系统部署、同步机制,可有效地实现试验任务数据接口同步.结果表明,在不影响试验任务数据处理与传输的实时性及可靠性的条件下,XML物化视图远程增量维护有效地实现了指挥显示系统数据接口的一致性.  相似文献   

3.
为有效降低视图增量计算的代价,提出了净化操作和主外码约束的优化同步计算方法.数据源基表的更新操作可能对同一元组多次反复的修改,而在视图增量的维护中并不需要反映基表的整个更新过程,而只是维护某个时间的状态一致,因而利用净化操作减少了计算的数据量.数据源基表间的主外码约束使得部分增量子查询的结果为空,减少这样的增量子查询提高了计算的效率.实验分析表明优化后的同步计算方法有效地降低了计算和维护代价.  相似文献   

4.
实化视图维护是指在数据源的原始数据发生改变时,有效地将这种变化反映到数据仓库中,使相应的实化视图得到及时更新.当前的视图维护方法主要以C/S结构为基础,当更新频繁时将会导致数据仓库超载而崩溃.针对这种现状,提出基于维护查询任务进行分解的实化视图并行增量维护P3Sweep算法,算法修正了Sweep算法只能顺序处理的限制,赋予其并行处理能力.对于单个更新,P3Sweep算法通过对维护查询任务进行分解,并行执行左右扫描过程来完成维护演算;对于并发更新,算法通过递归分解方式进行细粒度并行演算.性能计算和实验测试结果表明,该方法增加了系统对更新的吞吐能力,减少了维护的延迟,从维护查询任务本身实施对实化视图维护的优化.  相似文献   

5.
数据仓库中物化视图维护算法的分析和比较   总被引:1,自引:0,他引:1  
随着数据源的更新,数据仓库中的物化视图必须得到及时的更新维护.而如何对物化视图进行高效的更新,以满足用户对查询响应速度和查询结果一致性、时新性的要求,这是数据仓库技术中非常复杂和重要的工作,也是一个迫切需要解决的关键性技术问题.以物化视图更新维护问题为主要研究对象,通过对现有各种维护算法深入的研究和分析,系统地进行了比较和总结,最后指出了谊问题深入研究的方向.  相似文献   

6.
物化视图是减少数据仓库中查询响应时间的有效方法.现有的物化视图选择策略主要考虑物化视图的初始选择方法以及动态更新方法.针对某时间段内查询进行物化视图更新的情况考虑不足,在贪心算法以及动态更新算法的基础上,提出了基于时间段内查询的物化视图更新策略.基于时间段查询的物化视图更新策略可充分适应用户需求,提高查询效率.  相似文献   

7.
Web数据集成系统基于QC模型的物化视图选择   总被引:2,自引:0,他引:2  
在Web数据集成系统中,物化视图能够有效地减少网络传输代价,提高系统的查询效率.如何选择查询进行物化,使得选中的查询满足集成层的空间限制,同时获取最大物化收益,成为集成系统中一个迫切需要解决的问题.传统方法没有考虑到海量XML查询之间的包含关系,其选择的物化视图中可能包含冗余的信息.针对上述问题,提出了①Web数据集成系统中海量查询集合的QC(query containment)模型,该模型能够捕捉查询之间最常见的包含关系;②基于QC模型的物化视图选择算法,算法考虑了物化视图选择相关的主要因素,包括查询提交的频率、空间代价、查询重写能力和查询结果的完备性,提出了查询位图的物化视图组织方式,从而获取更加合理的物化视图选择方案.实验结果证明了该方法的有效性.  相似文献   

8.
针对含聚集物化视图的增量维护问题,提出了一种基于逐步更新思想的增量维护模型和方法.该方法建立了聚集函数计算前查询结果与基表记录之间的映射关系表,并根据映射关系表的增量变化更新物化视图的聚集函数.针对之前方法对于MAX/MIN聚集函数增量更新的不足,在仅利用增量数据不能更新聚集函数值时,采用仅重新计算映射关系表中相关行的MAX/MIN函数值的方法,极大地减小了更新MAX/MIN聚集函数的计算量.在OSCAR数据库的应用表明了该方法的有效性和高效性.  相似文献   

9.
数据仓库中多数据源物化视图的一种有效更新算法   总被引:4,自引:0,他引:4  
数据仓库中存储着大量的汇总数据以支持查询和相关决策的制定,这些汇总数据常常是定义在若干数据源上的物化视图.当数据源发生变化时,物化视图也需要相应的更新,这必然给数据仓库带来庞大的开销,因而如何有效地对物化视图进行更新成为一个非常重要的问题.利用BinPartition算法可以使计算费用达到最低,随后证明了该算法的正确性并分析了其时间复杂性.  相似文献   

10.
基于多维护策略的物化视图选择方法   总被引:1,自引:0,他引:1  
物化视图是数据仓库环境中提高OLAP查询效率的重要手段,因此,物化视图的选择是数据仓库设计中重要的决策之一。本文提出的物化视图选择方法目标是选择合适的视图进行物化,使得查询处理的总代价和物化视图的维护代价最低,提出了物化视图收益模型,并在此基础上基于视图的多维护策略提出了物化视图选择的方法:基于增量和重计算的物化视图选择算法IRMVS、基于增量策略的物化视图选择算法IMVS和基于重计算策略的物化视图选择算法RMVs和基于增量策略的物化后代视图选择算法IMDVS,理论分析和实验表明这些算法是有效可行的。  相似文献   

11.
Database systems employ physical structures such as indexes and materialized views to improve query performance, potentially by orders of magnitude. It is therefore important for a database administrator to choose the appropriate configuration of these physical structures for a given database. XML database systems are increasingly being used to manage semi-structured data, and XML support has been added to commercial database systems. In this paper, we address the problem of automatic physical design for XML databases, which is the process of automatically selecting the best set of physical structures for a database and a query workload. We focus on recommending two types of physical structures: XML indexes and relational materialized views of XML data. We present a design advisor for recommending XML indexes, one for recommending materialized views, and an integrated design advisor that recommends both indexes and materialized views. A key characteristic of our advisors is that they are tightly coupled with the query optimizer of the database system, and they rely on the optimizer for enumerating and evaluating physical designs. We have implemented our advisors in a prototype version of IBM DB2 V9, and we experimentally demonstrate the effectiveness of their recommendations using this implementation.  相似文献   

12.
Joseph Fong  Herbert Shiu  Davy Cheung 《Software》2008,38(11):1183-1213
Integrating information from multiple data sources is becoming increasingly important for enterprises that partner with other companies for e‐commerce. However, companies have their internal business applications deployed on diverse platforms and no standard solution for integrating information from these sources exists. To support business intelligence query activities, it is useful to build a data warehouse on top of middleware that aggregates the data obtained from various heterogeneous database systems. Online analytical processing (OLAP) can then be used to provide fast access to materialized views from the data warehouse. Since extensible markup language (XML) documents are a common data representation standard on the Internet and relational tables are commonly used for production data, OLAP must handle both relational and XML data. SQL and XQuery can be used to process the materialized relational and XML data cubes created from the aggregated data. This paper shows how to handle the two kinds of data cubes from a relational–XML data warehouse using extract, transformation and loading. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

13.
Optimizing queries using materialized views has not been addressed adequately in the context of XML due to the many limitations associated with the definition and usability of materialized views in traditional XML query evaluation models.  相似文献   

14.
在传统的实化视图维护时,数据源把增量数据以XML文档的方式报送给数据仓库,数据仓库从此文档中解析出数据,利用JDBC完成对实化视图的更新。文中提出在数据源把增量数据封装成序列化对象存储于文件中再报送给数据仓库,而数据仓库从文件中读出对象,利用Hibernate直接把对象更新到实化视图。通过两种方案性能的比较,表明后一种方案是可行并且更加高效的。  相似文献   

15.
数据仓库中用存储大量的物化视图来加速OLAP的查询响应,物化视图的选取是数据仓库设计中的一个重要问题。论文提出了一个有效的物化视图选取算法,采用基于数据立方体层次搜索的方式选取视图。经分析与测试表明,该算法取得良好的效果和效率。  相似文献   

16.
The research presented in this paper supports the identification of common subexpressions as candidates for potential materialized views that form the basis of multiple query optimization in a loosely-coupled distributed system where query expressions access heterogeneous data sources, including relations and data-centric XML. This paper introduces a unifying mixed multigraph formalism to represent SQL, XQuery, and LINQ queries in a common query graph model and a heuristics-based algorithm to detect common subexpressions. The identified common subexpressions represent an opportunity for defining a materialized view to avoid repeating computation. The common subexpressions may access only relations, only XML, or a combination of relations and XML. The mixed multigraph model and the heuristic rules presented in this paper have distinguished advantages over the existing approaches that consider only relational or XML data sources individually. The mixed multigraph model can present SQL, XQuery, and LINQ queries in a single graph model and the heuristic rules are designed to consider the identical and subsumed conditions at the same time. A prototype implementation of the algorithm illustrates the applicability of the approach using various examples from the research literature as well as scenarios over a Criminal Justice enterprise that include common subexpressions across relational and XML data sources.  相似文献   

17.
We present ViewDF: a flexible and declarative framework for incremental maintenance of materialized views (i.e., results of continuous queries) over streaming data. The main component of the proposed framework is the View Delta Function (ViewDF), which declaratively specifies how to update a materialized view when a new batch of data arrives. We describe and experimentally evaluate a prototype system based on this idea, which allows users to write ViewDFs directly and automatically translates common classes of streaming queries into ViewDFs. Our approach generalizes existing work on incremental view maintenance and enables new optimizations for views that are common in stream analytics, including those with pattern matching and sliding windows.  相似文献   

18.
We describe the Enosys XML integration platform, focusing on the query language, algebra, and architecture of its query processor. The platform enables the development of eBusiness applications in customer relationship management, e-commerce, supply chain management, and decision support. These applications often require that data be integrated dynamically from multiple information sources. The Enosys platform allows one to build (virtual and/or materialized) integrated XML views of multiple sources, using XML queries as view definitions. During run-time, the application issues XML queries against the views. Queries and views are translated into the XCQL algebra and are combined into a single algebra expression/plan. Query plan composition and query plan decomposition challenges are faced in this process. Finally, the query processor lazily evaluates the result, using an appropriate adaptation of relational database iterator models to XML. The paper describes the platform architecture and components, the supported XML query language and the query processor architecture. It focuses on the underlying XML query algebra, which differs from the algebras that have been considered by W3C in that it is particularly tuned to semistructured data and to optimization and efficient evaluation in a system that follows the conventional architecture of database systems.  相似文献   

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