AMAR Pandey

• Nov 22nd, 2007

 

Business Users needed to build queries that summarized the data and fed management reports. Such queries, were extremely slow because they usually summarize large amounts of data, while sharing the database engine with every day operations,
Reason1
which in turn adversely affected the performance of operational systems.
Reason2
Delay in strategic planning of the enterprise.

The solution was, therefore, to separate the data used for reporting and decision
making from the operational systems. Hence, data warehouses were designed and built to house this kind of data so that it can be used later in the strategic planning of the enterprise.

VAMSIKRISHNACH

 Profile Answers by VAMSIKRISHNACH 

• Dec 9th, 2007

 

Moreover BI tools need historical data also which is not present in OLTP sysms

praveen.p

 Profile Answers by praveen.p 

• Mar 5th, 2008

 

I think the more specific and technical answer would be the noremalized and denormalized form of data that exists in OLTP and OLAP machines. In OLTP machine you want to keep the data normalized because you want the transaction or the machine to be fast. In OLAP machine you want to keep the data denormalized because the of the complex Querying by the DSS tools.