DW的元数据是指除去数据本身之外的所有信息. 围绕DBMS方面的元数据可以描述为表定义,分区设置,索引视图定义,以及DBMS级安全方面的特权 与授权等内容. 在任何场合下,ODS要么是一个处在OLTP和DW之间的第三方物理系统,要么是DW的一个专门管理 的热区(用于支持实时交互操作,数据查询具有固定的结构形式)? 事实表的一行对应一个度量值,一个度量值就是事实表的一行,事实表的所有度量值必须具有相同的 粒度. 可加性事实:销售额 半可加性事实:库存 余额(除时间之外的维度可以用于聚合) 非可加性…

以下内容,常读常新,每次都有新的感悟和认识. 数据仓库必须使组织机构的信息变得容易存取. 数据仓库的内容需要是容易理解的,数据对业务人员也必定是直观的,明显的. 数据仓库重新组织了原来OLTP数据库的结构,根据业务需求,但又结合数据建模的一些特性. 数据仓库必须一致地展示组织机构的信息. 数据仓库中的数据必须是可信的,这就需要ETL能够保证数据是准确的. 数据仓库必须具有的适应性和便于修改. 其实任何软件的架构都应该考虑扩展性,所以有自己的一套设计模式.在数据仓库的设计中, 不应该根据具体的报表…

Atitit HTTP认证机制基本验证 (Basic Authentication) 和摘要验证 (Digest Authentication)attilax总结 1.1. 最广泛使用的是基本验证 (Basic Authentication) 和摘要验证 (Digest Authentication).1 1.2. 关于HTTP AUTH的文档不多.1 1.3. 什么是HTTP基本认证1 1.4. 适用场合 路由器 摄像头2 1.5. 其他认证  除了基本认证(Basic Authenticat…

After learning the basic opreation of Redis,we should take some time to summarize the usage. And I wrote my first edition RedisHelper.Here is the code: The Interface IRedis: public interface IRedis { ITransaction GetTransaction(, bool isRead = false)…

Data play an important part in our project,how can we ensure correctness of the data and prevent the data from error.In relational database, we are famillar with the usage of transaction. begin opreations commit/rollback But there are some difference…

This post is mainly about the publishment and subscription in Redis.I think you may subscribe some offiial accounts on wechat,and when the authors published something new to their accounts,you will get them in your wechat.The instance can make you un…

Redis's List is different from C#'s List,but similar with C#'s LinkedList.Sometimes I confuse with them.I expect that you won't mix them and have a clear mind of them. There are 17 commands we can use in List. Push and pop are the base opreation of t…

The last post is mainly about the unsorted set,in this post I will show you the sorted set playing an important role in Redis.There are many command added after the version 2.8.9.OK,let's see the below picture firstly.There are 24 commands to handle…

This post will introduce you to some usages of Set in Redis.The Set is a unordered set,it means that the data was stored in the database randomly.And there are 15 commands you can use in Redis,the same as Hash. For storing the data to database,we can…

When you first saw the name of Hash,what do you think?HashSet,HashTable or other data structs of C#?As for me, the first time I saw the Hash,I considered is as the HashTable.Actually,Hash can identify with HashTable,the same as DataRow.A row data of…