事实表是规范化形式还是非规范化形式？

问题描述

无论事实表是规范化还是非规范化的，我都对事实表进行了一些研发。
我遇到了一些发现，这使我感到困惑。

根据：

我也认为可以的另一个发现，：

所以我的问题是事实表是规范化还是非规范化？如果有任何这些，怎么办？为什么？

解决方案

从关系数据库设计理论的角度来看，维度表通常位于2NF中，事实表通常位于2NF与6NF之间的任何位置。

但是，尺寸建模是 ，它专门针对：

• 一个用例，即报告




• 主要是查询的一种基本类型（模式）




• 一个主要的用户类别-业务分析师或类似的




• 行存储RDBMS，例如Oracle，SQl Server，Postgres ...




• 一个独立控制的加载/更新过程（ETL）；所有其他客户端都是只读的

还有其他DW设计方法，例如

• Inmon的-数据结构驱动




• 数据保管库-数据结构驱动




• 锚点建模-模式演化驱动

I did a bit R&D on the fact tables, whether they are normalized or de-normalized. I came across some findings which make me confused.

According to Kimball:

The other finding, which I also I think is ok, by fazalhp at GeekInterview:

So my question is, are fact tables normalized or de-normalized? If any of these then how & why?

解决方案

From the point of relational database design theory, dimension tables are usually in 2NF and fact tables anywhere between 2NF and 6NF.

However, dimensional modelling is a methodology unto itself, tailored to:

• one use case, namely reporting

• mostly one basic type (pattern) of a query

• one main user category -- business analyst, or similar

• row-store RDBMS like Oracle, SQl Server, Postgres ...

• one independently controlled load/update process (ETL); all other clients are read-only

There are other DW design methodologies out there, like

• Inmon's -- data structure driven

• Data Vault -- data structure driven

• Anchor modelling -- schema evolution driven

The main thing is not to mix-up database design theory with specific design methodology. You may look at a certain methodology through database design theory perspective, but have to study each methodology separately.

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