Staging area data warehouse basics

Staging areas are used to temporarily store data extracted from source systems so that it can be prepared for subsequent cleansing and transformation.

Table structures usually are very similar to the table structure or file layouts in the source systems and are a series of “flat” table structures. In other words, they have no indexes and no relationships to other tables in the staging area.

Data structures may be designed to include:

• In-scope data e.g. only data in scope is loaded in the staging area; or
• All data, e.g. all data in the source table or files is loaded in the staging area and subsequent transformations eliminate non-essential data.

Data is loaded into staging area using fast load techniques and is transformed to ensure basic compatibility with the staging area structures e.g.

• Dates might be transformed from mm/dd/yy to yy/mm/dd; or
• Numeric values might be converted to varchar (if not needed for reporting).

Why Union Vs Join ?

Consider all related dimensions while loading it

Need to IDentify te Cube that u aregoing to build

How logical is your DB ?