1.Data Model Model Is the abstraction of real world Reveal the essence of objects, help people to locate and resolve problems Data Model A data model explicitly determines the structure of data, and defines the operation that can be imposed, in order…

1.Database concepts (1)Data & Information Information Is any kind of event that affects the state of a dynamic system Is the message (utterance or expression) being conveyed Is an ordered sequence of symbols that can be interpreted as a message As se…

Recovery Types of Failures Wrong data entry Prevent by having constraints in the database Fix with data cleaning Disk crashes Prevent by using redundancy (RAID, archive) Fix by using archives Fire, theft, bankruptcy… Buy insurance, change profession……

SQL is a very-high-level language, in which the programmer is able to avoid specifying a lot of data-manipulation details that would be necessary in languages like C++. What makes SQL viable is that its queries are “optimized” quite well, yielding ef…

规范化问题的提出 在规范化理论出现以前,层次和网状数据库的设计只是遵循其模型本身固有的原则,而无具体的理论依据可言,因而带有盲目性,可能在以后的运行和使用中发生许多预想不到的问题. 在关系数据库系统中,关系模型包括一组关系模式,各个关系不是完全孤立的,数据库的设计较层次和网状模型更为重要. 如何设计一个适合的关系数据库系统,关键是关系数据库模式的设计,一个好的关系数据库模式应该包括多少关系模式,而每一个关系模式又应该包括哪些属性,又如何将这些相互关联的关系模式组建一个适合的关系模型,这些工作决定…

Data Management ObjectivesBy the end o this module, you should understand the fundamentals of data management, including:1.Explain typical data management operations.2.Describe typical user cases for inserting system fields.3.List the ways to obtain…

原文地址:http://www.javacodegeeks.com/2015/07/mysql-vs-mongodb.html 1. Introduction It would be fair to say that as IT professionals we are living in the golden age of data management era. As our software systems become more complex and more distributed,…

http://www.windowsazure.com/en-us/develop/net/fundamentals/cloud-storage/ Managing and analyzing data in the cloud is just as important as it is anywhere else. To let you do this, Windows Azure provides a range of technologies for working with relati…

场景3 Data Management 数据管理 性能优化 OLTP OLAP 物化视图 :表的快照 传输表空间 :异构平台的数据迁移 星型转换 :事实表 OLTP : 在线事务处理 1. transaction —> DML 2. 数据量小 3. 处理时间短 —> SQL 共享,绑定变量 4. 并发量大 OLAP,DSS 1. 以查询为主(海量)—> 数据汇总 —> 结果放到表(物化视图)里 2. 处理时间长 3. 几乎无并发 4. 做并行处理 SGA + PGA memory_…

Lifetime-Based Memory Management for Distributed Data Processing Systems (Deca:Decompose and Analyze)   一.分布式数据处理系统像Spark.FLink中的优缺点: 1.优点: in-memory中可以通过缓存中间数据以及在shuffle buffer中组合和聚合数据最小化重复 计算和I/O花销来提升多阶段和迭代计算性能. 2.缺点: (1)会在堆中产生大量的长期生存的对象,因而产生很多GC,尤…