Wednesday, 4 February 2015

Technical Round DataStage Model Interview Questions and Answers (Part4)

31. What is fact table?
The chief feature of a star schema is the table at the center, called the fact table.

32. What are the advantages of data warehousing?
A data warehousing strategy provides the following advantages :
? Capitalizes on the potential value of the organization’s information.
? Improves the quality and accessibility of data.
? Combines valuable archive data with the latest data in operational sources.
? Increases the amount of information available to users.
? Reduces the requirement of users to access operational data.
? Reduces the strain on IT departments, as they can produce one database to serve all user groups.
? Allows new reports and studies to be introduced without disrupting operational systems.
? Promotes users to be self sufficient.

33. What is container?
Containers are the reusable set of stages.

34. What is the difference between local and shared container?
Local Container is local to the particular job in which we developed the container.
Shared Container is can be used in any other jobs also.

35. What is orabulk Stage?
This Stage is used to Bulk Load the Oracle Target Database.

36. What is the difference between active and passive Stage?
Passive Stages are used for data extraction and loading.
Active Stage are used to implements and process the business rules

37. What is meta data repository?
Meta Data is a data about the data. It also contains
? Query statistics
? ETL statistics
? Business subject area
? Source Information
? Target Information
? Source to Target mapping Information

38. What is the difference between join stage and merge stage?
JOIN : Performs join operations on two or more data sets input to the stage and then outputs the resulting dataset.
MERGE : Combines a sorted master data set with one or more sorted updated data sets. The columns from the rccords in the master and update data set s arc merged so that the out put record contains all the columns from the master record plus any additional columns from each update record that required.

39. What is the default cache size?
Default cache size is 256 MB.

40. How do you schedule or monitoring the job?
Using the DataStage Director we can schedule or monitor the job.
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