DWH Interview Question and Answers

21. What is BI?
  Business Intelligence, it is an ongoing process of various integration packages to analyze data.
 
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22. What are the Different types of OLAP’s?
  OLAP - Desktop OLAP(Cognos), ROLAP, MOLAP(Oracle Discoverer).
ROLAP, MOLAP and HOLAP are specialized OLAP (Online Analytical Analysis) applications.
  • ROLAP stands for Relational OLAP. Users see their data organized in cubes with dimensions, but the data is really stored in a Relational Database (RDBMS) like Oracle. The RDBMS will store data at a fine grain level, response times are usually slow.
  • MOLAP stands for Multidimensional OLAP. Users see their data organized in cubes with dimensions, but the data is store in a Multi-dimensional database (MDBMS) like Oracle Express Server. In a MOLAP system lot of queries have a finite answer and performance is usually critical and fast.
  • HOLAP stands for Hybrid OLAP, it is a combination of both worlds. Seagate Software's "Holos" is an example HOLAP environment. In a HOLAP system one will find queries on aggregated data as well as on detailed data.
 
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23. What is an ETL or ETT?
  ETL is the Data Warehouse acquisition processes of Extracting, Transforming (or Transporting) and Loading (ETL) data from source systems into the data warehouse.
 
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24. What do you mean by data mining?
  A data mining dimension provides support for dimensions that result from data-mining models.
 
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