a2zinterviews

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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