DWH Interview Question and Answers

17. What are the disadvantage of molap?
  Disadvantages of MOLAP are:
  • MOLAP tools are costlier as compared to ROLAP tools.
  • The cubes require high storage.
  • Data cubes have to be updated periodically as the summaries keep changing.
  • MOLAP lacks flexibility because the data cubes in the server have to be predefined keeping in view the requirements analysis. Hence, drill up is very difficult.
 
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18. What are the advantages of molap?
  Advantages of MOLAP are:
  • It provides excellent performance in terms of response time to queries as the data is already stored in summarized form.
  • Only the results are sent to the client machine and hence the network bandwidth requirements are low.
  • Drill-down is very fast.
 
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19. What is meant by grain?
  Granularity of data is a very important factor in the design of fact table. In fact table, we can represent data at different atomic levels, called grains.
 
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20. What is the difference between data mining and data warehousing?
 
  • In data mining, the operational data is analyzed using statistical techniques and clustering techniques to find the hidden patterns and trends. So, the data mines do some kind of summarization of the data and can be used by data warehouses for faster analytical processing for business intelligence.
  • Data warehouse may make use of a data mine for analytical processing of the data in a faster way.
 
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