|
|
-
|
|
This is my second notes on fact table modeling. They are tips to improve performance and scalability.
Fact tables are often designed to be index light, meaning that indexes should be placed only to support reporting and cube processing.
Fact tables are often much larger in row count and data volum......
|
|
-
|
|
Finally here is my notes about fact table modeling.
A fact table is the center of the star schema
It contains two primary types of data: Key columns and Data columns.
Fact table holds the keys to relate the needed dimension tables
Many OLAP tools, such as Analysis Services, look for star schem......
|
|
-
|
|
This is my last notes on dimension modeling.
Avoid unnecessary normalizing. In a star schema, the practice of normalizing is called snowflaking. This is usually unnecessary, unless your dimension tables is so large it needs to be physically separated on the storage array.
CamelCasing, the capita......
|
|
-
|
|
Here is my notes #11. About dimension again.
It’s easier to demonstrate the Type 0, Type 1 and Type 2 and Type 3 SCD (Slowly Changing Dimension) using the SCD Wizard in SSIS.
Type 0: any change in the dimension column is treated as errors.
Type 1: Update changing data only, no historical ......
|
|
-
|
|
Here is my notes #10.
On a very high level, dimensions provides the means to "slice and dice" data in a data warehouse. The primary function of dimensions is threefold: to provide filtering, grouping and labeling. It answers the where-clause questions for us. Look for word “by” in busin......
|
|
-
|
|
I guess my notes about dimension modeling will not be very complete if I do not show a typical snowflake schema.
In this typical snowflake schema example, the dimension Product is normalized, because the Product Sub Category is stored in a separate table ProductSubCategory. ProductSubCategory is al......
|
|
-
|
|
Here is my notes #8 about more keys in a star schema.
In the previous notes, MS BI Workshop #7 – What are all those keys in a star schema?, I showed two typical keys you are seeing in a dimensional table, a surrogate key and an alternate key.
In this notes, I will show two types of foreign k......
|
|
-
|
|
Here is my notes #7 about all those keys we’ve seen in a star schema.
This dimensional table is very typical. It has a primary key CurrencyKey, and an alternate key Currency code.
The above snapshot is from the DSV of SSAP project Adventure Works DW 2008 in BIDS. The table type is View (......
|
|
-
|
|
Here is my notes #6.
It’ll be redundant to write down all my notes because there are endless information about dimensional modeling. I’ll just write down the highlights from my notes.
Both 3NF models and dimensional models can be represented in ERDs.
The key difference is the degree......
|
|
-
|
|
Here is my notes #5.
Tons of books and articles and seminars have been produced telling us why we need BI. But why do I want to pursue a career as a BI developer? This is a question I often ask myself.
A few years back, I was offered a job as a MicroStrategy developer, and I turned it down. My re......
|
|