DataStage Interview Questions Answers and Explanations

3/26/2010 1 Comment

DataStage Interview Questions and Answers, Solution and Explanation.

Explain how did you handle reject data in Datastage?
Answer :
 Usually, a Reject-link is defined and the rejected data is loaded back into data warehouse. So Reject link has to be defined every Output link you wish to collect rejected data. Rejected data is typically bad data like duplicates of Primary keys or null-rows where data is expected.

What do you mean by Routines and where/how are they written and have you written any routines before?
Answer :
Routines are stored in the Routines branch of the DataStage Repository, where you can create, view or edit. The following are different types of routines:

  • Transform functions
  • Before-after job subroutines
  • Job Control routines
What do you mean by OConv () and Iconv () functions and where are they used?
Answer :
 Thery are conversion functions.

IConv() - Converts a string to an internal storage format
OConv() - Converts an expression to an output format.

Describe in brief about METASTAGE?
Answer :
MetaStage is used to handle the Metadata which will be very useful for data lineage and data analysis later on. Meta Data defines the type of data we are handling. This Data Definitions are stored in repository and can be accessed with the use of MetaStage.

Answer :
Qulaity Stage can be integrated with DataStage, In Quality Stage we have many stages like investigate, match, survivorship like that so that we can do the Quality related works and we can integrate with datastage we need Quality stage plugin to achieve the task.

What is the main differences between Oracle8i and Oracle 9i database?
Answer :
Oracle 8i does not support pseudo column sysdate but 9i supports
Oracle 8i we can create 256 columns in a table but in 9i we can upto 1000 columns(fields)

Explain how do you merge two files in Datastage?
Answer :
 You can either use Copy command as a Before-job subroutine if the metadata of the 2 files are same or create a job to concatenate the 2 files into one if the metadata is different.

Explain the usage of Datastage Designer? Also, describe the usage of DS Administrator?
Answer :
We can use the Designer to build jobs by creating a visual design that models the flow and transformation of data from the data source through to the target warehouse. The Designer graphical interface lets you select stage icons, drop them onto the Designer work area, and add links.

The Administrator enables you to set up DataStage users, control the purging of the Repository, and, if National Language Support (NLS) is enabled, install and manage maps and locales.

What is DS Director  and 
DS Manager used for?
Answer : Datastage director is used to run the jobs and validate the jobs. We can go to Datastage director from Datastage designer it self.
The Manager is a graphical tool that enables you to view and manage the contents of the DataStage Repository

What do you mean by Hash file stage and explain its usage?
Answer : It is u
sed for Look-ups. It is like a reference table. It is also used in-place of ODBC, OCI tables for better performance.

Explain in brief how are the Dimension tables designed in Datastage?
Answer :
 The dimension tables are designed by the following steps.

  • Finding where data for this dimension are located.
  • Figuring out how to extract this data.
  • Determining how to maintain changes to this dimension.
  • Changing fact table and DW population routines.
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