分布式数据库设计(共82张PPT).pptx

分布式数据库设计 A FRAMEWORK FOR DISTRIBUTED DATABASE DESIGN (概述) THE DESIGN OF DATABASE FRAGMENTATION (分片设计) THE ALLOCATION OF FRAGMENTS (分 配设计); Level of sharing 共享维 不共享，数据共享，数据+程序 共享 Access pattern behavior访问模式维 静态模式，动态 模式(分布式数据库设计与查询处理) Level of knowledge 访问模式知识维用户完全已知或部 分已知访问模式; 存取模式 动态 静态 部分信息 数据 知识级别 数据+程序 完整信息 共享; 集中式数据库设计 1. Designing the conceptual schema which describes the integrated database 2. Designing the physical database,i.e., mapping the conceptual schema to storage areas and determining appropriate access methods.; 分布式数据库设计的特殊要求 +3.Designing the fragmentation. + 4. Designing the allocation of fragments,i.e. mapped to physical images; also the replication of fragments is determined.; 关于分片和分配的几点注意 Fragmentation design been partially analyzed in centralized systems with multiple storage devices. The allocation problem has been studied as the file allocation problem. The distinction between two problems is conceptually relevant one deals with the logical criteria which motivate the fragmentation of a global relation one deals with the physical placement of data at the various sites. 这两个问题通常是相互关联的，不可能独立地解决它们而 能确定最优的fragmentaion和allocation; 关于APPLICATION考虑因素： 分布式数据库设计包括：分布式数据库设计和相应的分布式应用设计 1. The site from which the application is issued (site of origin of the application). 2. The frequency of activation of the application (i.e.,在单位时间内被激活 的次数); applications which can be issued at multiple sites, we need to know the frequency of activation of each application at each site. 3. The number, type, and the statistical distribution of accesses made by each application to each required data object.; 设计目标 (Objectives) Processing locality数据处理的本地性 Availability and reliability of distributed data 分 布式数据的有效性和可靠性冗余控制 Workload distribution 工作负荷的合理分布 Storage costs and availability存储能力和费用; Processing locality Maximize processing locality corresponds to the simple principle of placing data a