Informatica INTERVIEW QUESTION & ANSWERS
||What are the main difference between Data Warehousing and Business Intelligence?
||Data Warehousing : is a way of storing data and creating information through leveraging data marts. DM's are segments or categories of information and/or data that are grouped together to provide 'information' into that segment or category. DW does not require BI to work. Reporting tools can generate reports from the DW.
Business Intelligence : is the leveraging of DW to help make business decisions and recommendations. Information and data rules engines are leveraged here to help make these decisions along with statistical analysis tools and data mining tools.
||What are the advantages of Dimensional modelling?
- Ease of use
- High performance
- Predictable,standard framework
- Extensible to accomodate unexpected new data elements and new design decisions
||What transformations are used for variable port?
- Expression Transformation
- Aggregated transformation
- Rank Transformation
||What is the difference between OLTP and OLAP?
- OLTP is nothing but OnLine Transaction Processing which contains a normalised tables. But OLAP Online Analtical Programming contains the history of OLTP data which is non-volatile acts as a Decisions Support System.
- OLTP systems are for doing clerical / operational processing of data whereas OLAP systems are for carrying out analytical processing of data.
- OLAP system contains the current data as well as the details of the transactions.
- OLTP system contains historical data, and also data in summarized form.
||What are the various aggregate calculations?
Aggregate functions are :