Staging area: Necessary or overhead?

In this article, let us see what a staging area is, its types and the reason to have one in your data warehouse.

Ok, what is a stage area?

It is that part of a data warehouse where data is stored physically (in database or in files), but as an intermediate step before loading the target data warehouse / data marts. It is where activities like cleansing, de-duplication, etc take place. It is like a pit stop for a racing car before reaching the destination.

Some characteristics of the staging area are

1. accessible to and owned by ETL / DW team
2. OLAP / reporting teams do not have access to it
3. indexed very little
4. ETL developers are usually free to create / drop tables, controlled though (by the architect or modeling team)

Types of staging areas:

1. Persistent staging – stage data is not deleted, if you want to maintain history.
2. Transient staging – stage data is deleted after each ETL load

Most data warehouses have one or more staging areas, the types being either persistent or transient or both.

But should you really have a stage area? Can’t you do without it? After all these days, ETL tools are more capable of handling more data in memory fully.

Is staging necessary or is it an overhead?

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