DataStage Interview Questions and Answers

Question.1  What is the difference between DataStage and Informatica?

Answer: DataStage support parallel processing which informatica doesn’t. Links are object in the DataStage ,in Informatica it’s a port to port connectivity .In Informatica, its easy to implement Slowly Changing Dimensions which is little bit complex in Data Stage. DataStage doesn’t support complete error handling.

Question.2 What are the components of Ascential Data Stage?

Answer: Client Components – Administrator, Director, Manager, and Designer.

Server Components – Repository, Server and Plug-ins.

Question.3  What are System variables?

Answer:  System variables comprise of a set of variables which are used to get system information and they can be accessed from a transformer or a routine. They are read only and start with an @.

Question.4  What are the enhancements made in datastage 7.5 compare with 7.0?

Answer: Many new stages were introduced compared to datastage version 7.0. In server jobs we have stored procedure stage, CDC Stage ,command stage and generate report option was there in file tab. In job sequence many stages like startloop activity, end loop activity,terminate loop activity and user variables activities were introduced. In parallel jobs surrogate key stage, stored procedure stage were introduced..

Question.5 What is DataStage?

Answer:  Design jobs for Extraction, Transformation and Loading(ETL).Ideal tool data integration projects such as data warehouses, data marts and system migrations.Import,export,create and managed metadata for use within jobs.Schedule, run and monitor jobs all within DataStage Adminsters your Datastage development and execution environments.

Question.6 What is a merge?

Answer: Merge is a stage that is available in both parallel and server jobs.The merge stage is used to join two tables(server/parallel) or two tables/datasets(parallel).Merge requires that the master table/dataset and the update table/dataset to be sorted. Merge is performed on a key field, and the key field is mandatory in the master and update dataset/table.  

Question.7  What are Sequencers?

Answer: A sequencer allows you to synchronize the control flow of multiple activities in a job sequence. It can have multiple input triggers as well as multiple output triggers.

Question.8  What is version Control?

Answer: Version Control stores different versions of DS jobs runs different versions of same job reverts to previous version of a job view version histories.                      

Question.9  what is Active and Passive Stage?

Answer: Passive Stages are used for data extraction and loading ,while Active Stage are used to implements and process the business rules.

Question .10   What are the main features of datastage?

Answer: DataStage has the following features to aid the design and processing required to build a data warehouse :Uses graphical design tools. With simple point and click techniques you can draw a scheme to represent your processing requirements. Extracts data from any number or types of database.Handles all the metadata definitions required to define your data warehouse. You can view and modify the table definitions at any point during the design of your application.

Aggregates data. You can modify SQL SELECT statements used to extract data. Transforms data. DataStage has a set of predefined transforms and functions you can use to convert your data. You can easily extend the functionality by defining your own transforms to use.Loads the data warehouse.

Question.11 Define data aggregation?

Answer: An operational data source usually contains records of individual transactions such as product sales. If the user of a data warehouse only needs a summed total, you can reduce records to a more manageable number by aggregating the data. 

Question.12 How the IPC Stage work?

Answer: If we used the IPC Stage between source and target .One process will handling the communication from sequential file stage to IPC stage, and other will handling communication from IPC stage to ODBC stage. As soon as the Sequential File stage has opened its output link, the IPC stage can start passing data to the ODBC stage.  

Question.13    What are stage variables?

Answer: An intermediate processing variable that retains value during read and doesn’t pass the value into target column.

Question.14    What are the types of Containers?

Answer:  There are Two types of containers namely

                      Local Container

                      Shared Container

Question.15    Where the DataStage stored his repository?

Answer:  DataStage stored his repository in IBM Universe Database.

Question.16 What is Staging Variable?

Answer: These are the temporary variables created in transformer for calculation.

Question.17    How do you generate Sequence number in Datastage?

 Answer:      Using the Routine

                       KeyMgtGetNextVal

                       KeyMgtGetNextValConn

They can also be done by Oracle Sequence.

Question.18 What is the difference between Server Job and Parallel Jobs?

Answer: Server Jobs works in sequential way while parallel jobs work in parallel fashion (Parallel Extender work on the principal of pipeline and partition) for Input/Output processing.

Question.19    What is the difference between Account and Directory options ?

Answer: Account option create the hashfile in the current project itself using condition and for Directory option we have to specify the path of the directory.

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