mdr.mohanrao

• Jun 20th, 2005

 

Denormalization is used when there is a lot of tables involved in retreiving data.Denormalization is done in dimentional modelling used to construct a data ware house.This is not usually done for data bases of transactional systems.

Sriharsha Hanumanth

• Aug 23rd, 2005

 

When the database performance is slow, we should consider denormalization.

Preeti Yadav

 Profile Answers by Preeti Yadav Questions by Preeti Yadav

• Apr 3rd, 2006

 

Denormalization is considering in terms of reporting applications, where a lot of data needs to filtered very often.

zahoorahmad

 Profile Answers by zahoorahmad 

• Apr 12th, 2006

 

When we have normalized (tables) data bases, then we have more number of tables relative to that data base which is not normalized.

So when queries are applied, joins would retrieve data from multiple tables then our processing would be slow.

So if u need high porcessing then keep ur table denormalized.

Preeti Yadav

• Apr 13th, 2006

 

When the database is already slow, how can u think of denormalization, it wud increase the overhead.

KP

• May 20th, 2006

 

This is one of those great, "It Depends" answers.  People following the "Kimball" approach will tell you almosgt always, "Inmon" almost Never.  But simply speaking Star is better in OLAP and Snowflake in Operational DBs or for ETL.

sachin

• Jun 25th, 2007

 

There are various reasons behind normalizing and denormalizing.
If you dig deep into the practical world, everywhere all the applications have both type of formation. You cannot deal with only one type of application.
Example of Practical Scenario:
Banking contains payments. Payments can happen accorss banks, borders and worlds. Hence standards would be different. Keeping this in picture, if you feel that the WH should be constructed region wise would be a big investment. Instead small databases are created with Data Mart in picture. It's not a full data mart. Companies prefer to create OLTP databases with concept of OLAP existing. Most important for any customer is quick response. A person wanting information about history would definitely have to wait even though the report would just take a min to generate. Coz this is business. Whereas a customer who is at the desk would need the info and at that time, the bank representative has to quickly retrieve the record, This can happen if normalization is done. Again here you would say that if it is too much normalized then it would be slow as there are more tables involved. This leads to the question which was raised.
Thus it's a combination based on the practical world's use and thus the designers think both way while preparing the chart way forward.

Regards,
Sachin.

geeksds

 Profile Answers by geeksds 

• Sep 18th, 2008

 

When there are performance issues, that would be improved by denormalizing the database.