Data Warehousing What is it?

Data Warehouse is big database which contain huge amount of data for analysis .
The data in data warehouse can come from heterogeneous sources as well as from homogeneous sources.
Heterogeneous sources mean data coming from differnet databases like DB2,Oracle etc.
Homogeneous sources mean data coming from same database.
So there are plenty of challenges to be overcome while building a data warehouse.

In the picture above you will data coming from various sources like OLTP etc.

The purpose of ETL layer after that(Informatica,Abinitio) is the data may not be in right format to be loaded into data warehouse.

Example will be data coming from source is in 'YYYY-MM-DD' format and we want another format like 'MM-DD-YYYY'.

After ETL we load data into Data Warehouse.

Plenty of Data bases are available which are present in current market to fulfil the requirement of data warehouse like Oracle 10g,Teradata and DB@.

The data base you choose depend on cost,skills available and few other factor.

Aprt from Data Warehouse we have data mart.

Data mart are subset of Data Warwehouse.In an organization you may have different lot of data mart.Data Mart specifically deal with one domain example finance.

There are two approaches of building data warehouse.

1. Top Down: Build Data Warehouse first and than Data mart

2. Bottom up:Build Data mart first and than Data warehouse.

After the data warehouse is build it can be used for various purpose like data reporting and data mining.

Data reporting can be done by various tools available in the market like cognos,Business Obects etc

Please post you comment.

Thanks for reading