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1、精品学习资源河北工程高校毕业论文（设计）英文参考文献原文复印件及译文数据仓库数据仓库为商务运作供应结构与工具，以便系统地组织、懂得和使用数据进行决策；大量组织机构已经发觉，在当今这个布满竞争、快速进展的世界， 数据仓库是一个有价值的工具；在过去的几年中，很多公司已花费数百万美 元，建立企业范畴的数据仓库；很多人感到，随着工业竞争的加剧，数据仓库成了必备的最新营销武器 通过更多地明白客户需求而保住客户的途径；“那么”，你可能会布满神奇地问， “究竟什么是数据仓库？ ”数据仓库已被多种方式定义，使得很难严格地定义它；宽松地讲，数据仓库是一个数据库，它与组织机构的操作数据库分别保护；数据仓库系统答应
2、将各种应用系统集成在一起，为统一的历史数据分析供应坚实的平台，对信息处理供应支持；依据 W. H. Inmon，一位数据仓库系统构造方面的领头建筑师的说法， “数据仓库是一个面对主题的、集成的、时变的、非易失的数据集合，支持治理决策制定 ”；这个简短论、文全题面的目定：义鸿指海出种了业数据仓仓库库管的理主系要统特点的；四个关键词，面向主题的、集成的、时变的、非易失的，将数据仓库与其它数据储备系统设计与实现（如，关系数据库系统、事务处理系统、和文件系统）相区分；让我们进一步看看这些关键特点；作者姓名：石成华专业班级：信管(1) 面对主题的：数据仓库环绕一些主题，如顾客、供应商、产品和销售组100
3、1织；数据仓库关注决策者的数据建模与分析，而不是构造组织机构的日常操作和事务处理；因此，学数号据信仓息库：排除对于1决0策03无40用1的19数据，供应特定主题的简明视图；(2) 集成的：通指常，导构老造师数：据仓库是张将贵多炜个异种数据源，如关系数据库、一论文日期：2021.04.101 / 10欢迎下载精品学习资源般文件和联机事务处理记录，集成在一起；使用数据清理和数据集成技术，确保命名商定、编码结构、属性度量的一样性等；(3) 时变的：数据储备从历史的角度（例如，过去5-10 年）供应信息；数据仓库中的关键结构，隐式或显式地包含时间元素；(4) 非易失的：数据仓库总是物理地分别存放数据；
4、这些数据源于操作环境下的应用数据；由于这种分别，数据仓库不需要事务处理、复原和并行掌握机制；通常，它只需要两种数据拜访：数据的初始扮装入和数据拜访；概言之，数据仓库是一种语义上一样的数据储备，它充当决策支持数据模型的物理实现，并存放企业决策所需信息；数据仓库也经常被看作一种体系结构，通过将异种数据源中的数据集成在一起而构造，支持结构化和启示式查 询、分析报告和决策制定；“好”，你现在问， “那么，什么是建立数据仓库？”依据上面的争论，我们把建立数据仓库看作构造和使用数据仓库的过程； 数据仓库的构造需要数据集成、数据清理、和数据统一；利用数据仓库经常需 要一些决策支持技术；这使得 “学问工人 ”
5、（例如，经理、分析人员和主管）能够使用数据仓库，快捷、便利地得到数据的总体视图，依据数据仓库中的信息 做出精确的决策；有些作者使用术语 “建立数据仓库 ”表示构造数据仓库的过程，而用术语 “仓库 DBM”S 表示治理和使用数据仓库；我们将不区分二者；“组织机构如何使用数据仓库中的信息？ ”很多组织机构正在使用这些信息支持商务决策活动，包括 :(1) 、增加顾客关注，包括分析顾客购买模式（如，宠爱买什么、购买时间、预算周期、消费习惯）；(2) 、依据季度、年、地区的营销情形比较，重新配置产品和治理投资， 调整生产策略；(3) 、分析运作和查找利润源；(4) 、治理顾客关系、进行环境调整、治理合股
6、人的资产开销；从异种数据库集成的角度看，数据仓库也是特别有用的；很多组织收集了形形色色数据，并由多个异种的、自治的、分布的数据源保护大型数据库；集成这些数据，并供应简便、有效的拜访是特别期望的，并且也是一种挑战；数据库工业界和争论界都正朝着实现这一目标竭尽全力；对于异种数据库的集成，传统的数据库做法是：在多个异种数据库上，建立一个包装程序和一个集成程序（或仲裁程序）；这方面的例子包括IBM 的数据连接程序和 Informix 的数据刀；当一个查询提交客户站点，第一使用元数据字典对查询进行转换，将它转换成相应异种站点上的查询；然后，将这些查询欢迎下载精品学习资源映射和发送到局部查询处理器；由不同
7、站点返回的结果被集成为全局回答；这种查询驱动的方法需要复杂的信息过滤和集成处理，并且与局部数据源上的处理竞争资源；这种方法是低效的，并且对于频繁的查询，特殊是需要集合操作的查询，开销很大；对于异种数据库集成的传统方法，数据仓库供应了一个好玩的替代方案；数据仓库使用更新驱动的方法，而不是查询驱动的方法；这种方法将来自多个异种源的信息预先集成，并储备在数据仓库中，供直接查询和分析；与联机事务处理数据库不同，数据仓库不包含最近的信息；然而，数据仓库为集成的异种数据库系统带来了高性能，由于数据被拷贝、预处理、集成、注释、汇总， 并重新组织到一个语义一样的数据储备中；在数据仓库中进行的查询处理并不影响在
8、局部源上进行的处理；此外，数据仓库储备并集成历史信息，支持复杂的多维查询；这样，建立数据仓库在工业界已特别流行；1. 操作数据库系统与数据仓库的区分由于大多数人都熟识商品关系数据库系统，将数据仓库与之比较，就简单懂得什么是数据仓库；联机操作数据库系统的主要任务是执行联机事务和查询处理；这种系统称 为联机事务处理（ OLTP）系统；它们涵盖了一个组织的大部分日常操作，如购买、库存、制造、银行、工资、注册、记帐等；另一方面，数据仓库系统在数 据分析和决策方面为用户或 “学问工人 ”供应服务；这种系统可以用不同的格式组织和供应数据，以便满意不同用户的形形色色需求；这种系统称为联机分析 处理（ OLA
9、P ）系统；OLTP 和 OLAP 的主要区分概述如下；(1) 用户和系统的面对性： OLTP 是面对顾客的，用于办事员、客户、和信息技术专业人员的事务和查询处理； OLAP 是面对市场的，用于学问工人（包括经理、主管、和分析人员）的数据分析；(2) 数据内容： OLTP 系统治理当前数据；通常，这种数据太琐碎，难以便利地用于决策； OLAP 系统治理大量历史数据，供应汇总和集合机制，并在不同的粒度级别上储备和治理信息；这些特点使得数据简单用于见多识广的决策；(3) 数据库设计：通常， OLTP 系统采纳实体 -联系（ ER）模型和面对应用的数据库设计；而OLAP 系统通常采纳星形或雪花模型和
10、面对主题的数据库设计；(4) 视图： OLTP 系统主要关注一个企业或部门内部的当前数据，而不涉及历史数据或不同组织的数据；相比之下，由于组织的变化，OLAP 系统经常跨欢迎下载精品学习资源越数据库模式的多个版本； OLAP 系统也处理来自不同组织的信息，由多个数据储备集成的信息；由于数据量庞大，OLAP 数据也存放在多个储备介质上；(5) 、拜访模式： OLTP 系统的拜访主要由短的、原子事务组成；这种系统需要并行掌握和复原机制；然而，对OLAP 系统的拜访大部分是只读操作（由于大部分数据仓库存放历史数据，而不是当前数据），尽管很多可能是复杂的 查询；OLTP 和 OLAP 的其它区分包括数
11、据库大小、操作的频繁程度、性能度量等；2. 但是，为什么需要一个分别的数据仓库“既然操作数据库存放了大量数据”，你留意到， “为什么不直接在这种数据库上进行联机分析处理，而是另外 花费时间和资源去构造一个分别的数据仓库？”分别的主要缘由是提高两个系统的性能；操作数据库是为已知的任务和负载设计的，如使用主关键字索引和散列，检索特定的记录，和优化 “罐装的 ”查询；另一方面，数据仓库的查询通常是复杂的，涉及大量数据在汇总级的运算，可能需要特殊的数据组织、存取方法和基于多维视图的实现方法；在操作数据库上处理OLAP 查询，可能会大大降低操作任务的性能；此外，操作数据库支持多事务的并行处理，需要加锁和
12、日志等并行掌握和 复原机制，以确保一样性和事务的强健性；通常，OLAP 查询只需要对数据记录进行只读拜访，以进行汇总和集合；假如将并行掌握和复原机制用于这 OLAP 操作，就会危害并行事务的运行，从而大大降低OLTP 系统的吞吐量；最终，数据仓库与操作数据库分别是由于这两种系统中数据的结构、内容和用法都不相同；决策支持需要历史数据，而操作数据库一般不保护历史数 据；在这种情形下，操作数据库中的数据尽管很丰富，但对于决策，经常仍是远远不够的；决策支持需要将来自异种源的数据统一（如，集合和汇总），产生高质量的、纯洁的和集成的数据；相比之下，操作数据库只保护具体的原始数据（如事务），这些数据在进行分
13、析之前需要统一；由于两个系统供应很不相同的功能，需要不同类型的数据，因此需要保护分别的数据库；Data warehousing provides architectures and tools for business executives to sy stematically organize, understand, and use their data to make strategic decisions. A lar ge number of organizations have found that data warehouse systems are valuable tools
14、 in todays competitive, fast evolving world. In the last several years, many firms have spent millions of dollars in building enterprise-wide data warehouses. Many people feel that with competition mounting in every ind ustry, data warehousing is the latest must-have marketing weapon 欢迎下载精品学习资源a way
15、 to keep customers by learning more about their needs.“ Soy, ou may ask, full of intrigue, “ whaet xactly is a data warehouse.Data warehouses have been defined in many ways, making it difficult to formulate a rigorous definition. Loosely speaking, a data warehouse refers to a database that is mainta
16、ined separately from an organizations operational databases. Data warehouse s ystems allow for the integration of a variety of application systems. They support info rmation processing by providing a solid platform of consolidated, historical data for a nalysis.According to W. H. Inmon, a leading ar
17、chitect in the construction of data wareho use systems,“adata warehouse is a subject-oriented, integrated, time-variant, and nonvolatile collection of data in support of managements decision making process. This short, but comprehensive definition presents the major features of a d ata warehouse. Th
18、e four keywords, subject-oriented, integrated, time-variant, and nonvolatile, distinguish data warehouses from other data repository syste ms, such as relational database systems, transaction processing systems, and file syste ms. Lets take a closer look at each of these key features.1.Subject-orien
19、ted: A data warehouse is organized around major subjects, such as customer, ven dor, product, and sales. Rather than concentrating on the day-to-day operations and transaction processing of an organization, a data warehouse focuse s on the modeling and analysis of data for decision makers. Hence, da
20、ta warehouses ty pically provide a simple and concise view around particular subject issues by excluding data that are not useful in the decision support process.2 Integrated: A data warehouse is usually constructed by integrating multiple he terogeneous sources, such as relational databases, flat f
21、iles, and on-line transaction records. Data cleaning and data integration techniques are applied to e nsure consistency in naming conventions, encoding structures, attribute measures, and so on.3.Time-variant: Data are stored to provide information from a historical perspective e.g., the past 5-10 y
22、ears. Every key structure in the data warehouse contains, either implicitly or expl icitly, an element of time.4Nonvolatile: A data warehouse is always a physically separate store of data tra欢迎下载精品学习资源nsformed from the application data found in the operational environment. Due to this separation, a
23、data warehouse does not require transaction processing, recovery, and co ncurrency control mechanisms. It usually requires only two operations in data accessi ng: initial loading of data and access of data.In sum, a data warehouse is a semantically consistent data store that serves as a p hysical im
24、plementation of a decision support data model and stores the information on which an enterprise needs to make strategic decisions. A data warehouse is also often viewed as an architecture, constructed by integrating data from multiple heterogeneous sources to support structured and/or ad hoc queries
25、, analytical reporting, and decisio n making.“ OK,you now ask, “ whatt,hen, is data warehousing.Based on the above, we view data warehousing as the process of constructing and using data warehouses. The construction of a data warehouse requires data integratio n, data cleaning, and data consolidatio
26、n. The utilization of a data warehouse often necessitates a collection of decision support technologies. This allow“s knowledgeworkers e.g., managers, analysts, and executives to use the warehouse to quickly and con veniently obtain an overview of the data, and to make sound decisions based on infor
27、 mation in the warehouse. Some authors use the ter“m datawarehousing to refer onlyto the process of data warehouse construction, while the term warehouse DBMS is used to refer to the management and utilization of data warehouses. We will not make thi s distinction here.“ Howare organizations using t
28、he information from data warehouses. Many organizations are using this information to support business decision making activities, in cluding:(1) increasing customer focus, which includes the analysis of customer buying pa tterns such as buying preference, buying time, budget cycles, and appetites f
29、or spendi ng,(2) repositioning products and managing product portfolios by comparing the performance of sales by quarter, by year, and by geographic regions, in order to fine- tune production strategies,(3) analyzing operations and looking for sources of profit,(4) managing the customer relationship
30、s, making environmental corrections, and managing the cost of corporate assets.Data warehousing is also very useful from the point of view of heterogeneous dat欢迎下载精品学习资源abase integration. Many organizations typically collect diverse kinds of data and main tain large databases from multiple, heteroge
31、neous, autonomous, and distributed infor mation sources. To integrate such data, and provide easy and efficient access to it is hi ghly desirable, yet challenging.Much effort has been spent in the database industry and research community tow ards achieving this goal.The traditional database approach
32、 to heterogeneous database integration is to buil d wrappers and integrators or mediators on top of multiple, heterogeneous databases. A variety of data joiner and data blade products belong to this category. When a quer y is posed to a client site, a metadata dictionary is used to translate the que
33、ry into quer ies appropriate for the individual heterogeneous sites involved. These queries are then mapped and sent to local query processors. The results returned from the different sit es are integrated into a global answer set. This query-driven approach requires complex information filtering an
34、d integration processes, and competes for resources with processing at local sources. It is inefficient and potentiall y expensive for frequent queries, especially for queries requiring aggregations.Data warehousing provides an interesting alternative to the traditional approach o f heterogeneous da
35、tabase integration described above. Rather than using a query- driven approach, data warehousing employs an update-driven approach in which information from multiple, heterogeneous sources is integra ted in advance and stored in a warehouse for direct querying and analysis. Unlike on- line transacti
36、on processing databases, data warehouses do not contain the most current information. However, a data warehouse brings high performance to the integrated he terogeneous database system since data are copied, preprocessed, integrated, annotate d, summarized, and restructured into one semantic data st
37、ore. Furthermore, query proc essing in data warehouses does not interfere with the processing at local sources. Mor eover, data warehouses can store and integrate historical information and support com plex multidimensional queries. As a result, data warehousing has become very popular in industry.1
38、. Differences between operational database systems and data warehouses Since most people are familiar with commercial relational database systems, it iseasy to understand what a data warehouse is by comparing these two kinds of systems.The major task of on-line operational database systems is to per
39、form on-欢迎下载精品学习资源line transaction and query processing. These systems are called on-line transaction processing OLTP systems. They cover most of the day-to-day operations of an organization, such as, purchasing, inventory, manufacturing, ban king, payroll, registration, and accounting. Data warehou
40、se systems, on the other hand, serve users or“ knowledgeworkers in the role of data analysis and decision making. Such systems can organize and present data in various formats in order to accommod ate the diverse needs of the different users. These systems are known as on-line analytical processing
41、OLAP systems.The major distinguishing features between OLTP and OLAP are summarized as f ollows.(1). Users and system orientation: An OLTP system is customer-oriented and is used for transaction and query processing by clerks, clients, and infor mation technology professionals. An OLAP system is mar
42、ket-oriented and is used for data analysis by knowledge workers, including managers, exe cutives, and analysts.(2). Data contents: An OLTP system manages current data that, typically, are toodetailed to be easily used for decision making. An OLAP system manages large amou nts of historical data, pro
43、vides facilities for summarization and aggregation, and stores and manages information at different levels of granularity. These features make the d ata easier for use in informed decision making.(3). Database design: An OLTP system usually adopts an entity- relationship ER data model and an applica
44、tion -oriented database design. An OLAP system typically adopts either a star or snowflake model, and a subject-oriented database design.(4). View: An OLTP system focuses mainly on the current data within an enterpri se or department, without referring to historical data or data in different organiz
45、ations. In contrast, an OLAP system often spans multiple versions of a database schema, due to the evolutionary process of an organization. OLAP systems also deal with informat ion that originates from different organizations, integrating information from many data stores. Because of their huge volu
46、me, OLAP data are stored on multiple storage me dia.(5). Access patterns: The access patterns of an OLTP system consist mainly of sh ort, atomic transactions. Such a system requires concurrency control and recovery me chanisms. However, accesses to OLAP systems are mostly read-欢迎下载精品学习资源only operati
47、ons since most data warehouses store historical rather than up-to- date information, although many could be complex queries.Other features which distinguish between OLTP and OLAP systems include data base size, frequency of operations, and performance metrics and so on. 2. But, why ha ve a separate
48、data warehouse.“ Sincoeperational databases store huge amounts of data, you observ“e,whynotperform on-line analytical processing directly on such databases instead of spending additional ti me and resources to construct a separate data warehouse.A major reason for such a separation is to help promote the high performance of both systems. An operational database is designed and tuned from known tasks and w orkloads, such as indexing and hashing using primary keys, searching for partic