Informatica Interview Question and Answers

56. How do you handle large datasets?
  By Using Bulk utility mode at the session level and if possible by disabling constraints after consulting with DBA; Using Bulk utility mode would mean that no writing is taking place in Roll Back Segment so loading is faster. However the pitfall is that recovery is not possible.
 
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57. What are the limitations of handling long datatypes?
  When the length of a datatype (e.g varchar2(4000)) goes beyond 4000, Informatica makes this as varchar2(2000).
 
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58. What are the types of OLAP?
  ROLAP (Relational OLAP) - Users see their data organized in cubes and dimensions but the data is really stored in RDBMS. The performance is slow. A storage mode that uses tables in a relational database to store multidimensional structures.
MOLAP (Multidimensional OLAP) - Users see their data organized in cubes and dimensions but the data is really stored in MDBMS. Query performance is fast.
HOLAP (Hybrid OLAP) - It is a combination of ROLAP and HOLAP. EG: HOLOs. In this one will find data queries on aggregated data as well as detailed data.
 
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59. What is the difference between data mart and data warehouse?
  Data mart used on a business division/department level where as data warehouse is used on enterprise level.
 
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60. What is Meta data?
  Data about the data, contains the location and description of data warehouse system components such as name, definitions and end user views.
 
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