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Top 50 Datastage Interview Questions and Answers


This blog for DataStage Interview Questions would help you with all the necessary information to clear the DataStage Interview. These questions are prepared by DataStage experts which are usually asked in all DataStage Interviews. This blog will cover questions at different levels like intermediates and advanced workforce.

Usually, the discussion starts from basics for each expert and moves towards advanced stage slowly. If DataStage is new for you or you want to know the DataStage concept in depth, then join the DataStage certification course at JanBask Training to give a new definition to your career.

DataStage Interview Questions And Answers

Q1). What is DataStage?

DataStage is basically a tool that is required for designing, developing, and executing multiple apps to fill different tables in a data mart or a data warehouse. It is a program majorly designed for Windows Servers extracting data from databases and converts them to data warehouses. Today, it is considered as an essential part of the IBM WebSphere Data Integration suite.

Q2). Name the command line function that is used to import DS jobs.

To import DS jobs, the dsimport.exe command is used.

Q3). Name the command line function that is used to export DS jobs.

To export DS jobs, the dsexport.exe command is used.

Q4). Explain the process for populating a source file in DataStage.

You may utilize two techniques for populating a source file in DataStage:

  • The source file can be populated by creating a SQL file in Oracle.
  • The source file can be populated using a row generator extract tool.

Q5). How DataStage versions 7.0 and 7.5 are different?

DataStage 7.5 is an advanced version of DataStage 7.0 where multiple stages are added for a smooth or robust performance like Command Stage, Procedure Stage, and Report generation stage, etc.

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Q6). How data file and descriptor file are different?

A Data file contains data while Descriptor file contains complete information about data stored in data files.

Q7). What is the process for fixing truncated data errors in DataStage tool?

You should use an environment variable for fixing data errors in DataStage tool.


Q8). How can DataStage and Informatica be compared?

In DataStage, there is a concept of data partition and data parallelism when it comes to node configuration. While there is no concept of data partition and data parallelism for node configuration. When it comes to benefits, Informatica is more scalable, and DataStage is more user-friendly.

Q9). What is the mechanism for writing parallel routines in DataStage?

With the help of C and C++ Compiler, parallel routines can be written in DataStage. You can also use the DS manager for creating parallel routines in DataStage. They can be called further through Transformation Stage.

Q10). What are Routines and its different types in DataStage?

Routines are basically collections of functions that can be defined with the help of a DS Manager. They can be called further through Transformation Stage. They are basically divided into three major categories:

  • Parallel Routines
  • Server routines
  • Main Frame Routines

Q11). How to remove duplicate values in DataStage?

Sort Stage can do it. Here, you should use the option, allow duplicates = False.

Q12). What is a Merger?

Merging means joining two tables together. It can be done with the help of a Primary key in both the tables.

Q13). Do you know the process for improving DataStage jobs?

To improve the performance of DataStage jobs, you should first define the baselines. Secondly, try using multiple flows for performance testing. Then start working in increments. Now, evaluate the data skews. Now you should isolate and solve the problem one by one. This is the time for distributing file systems to remove bottlenecks. RDBMS should not be used in the beginning. In the ned, you should understand and assess the available tuning knobs.

Q14). How are these three terms different – Merge, Join, and Lookup stage?

All three terms are different in terms of memory storage, input requirements, how they treat the records. Lookup stage needs high memory when compared to Merge and Join.

Q15). What is a Quality Stage in DataStage tool?

A quality stage is also termed as the Integrity Stage. It helps in integrating different types of data from multiple sources.

Q16). What is the meaning of term Job Control in DataStage tool?

With the Job Control Language (JCL), job control tasks are completed. It is used to execute multiple jobs simultaneously without using any loop.

Q17). How to differentiate massive parallel processing and symmetric processing?

Symmetric Processing:

  • In this case, hardware resources are shared by one processor.
  • Each processor has a dedicated operating system that communicates by shared memory.

Massive Parallel Processing:

  • In this case, the processor accesses the hardware resources exclusively.
  • It does not allow sharing and much faster than symmetric processing.

Q18). What is the process of killing a job in DataStage?

To kill a job, you should kill the respective processing ID.

Q19). Do you know the format for Date conversion in DataStage?

We can use date conversion function for this purpose i.e. Oconv(Iconv(filedname, "Existing date formate"), "Another date Format").

Q20). How to validate and compile a job in DataStage?

Validation means the execution of a job in DataStage. When validating a job, DataStage engine verifies either all properties are defined well or not. During compilation, the DataStage engine will check either all defined properties are valid or not.

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Q21). What is the meaning of the exception activity in DataStage?

The job executes even if there exists some unexpected error in case of exception activity with the help of a job sequencer.

Q22). What is the meaning of APT_CONFIG command in DataStage?

An environment variable is used for identifying apt files in DataStage. It can be used for storing node information, disk information, etc. from scratch.

Q23). Can you convert a server job to a parallel job?

With the help of an IPC Connector and Link Connector in DataStage, a server job can be converted to the parallel job.

Q24). How many types of Lookups exists in DataStage?

There are two types of lookups in DataStage, Normal Lookup and Sparse Lookup. In the case of Normal Lookup, data is first stored in memory, and lookup is performed later. In the case of Sparse lookup, data is saved to the database directly. It is faster than the normal lookup.

Q25). What is a repository table in DataStage?

A repository table works as a data warehouse that can either be centralized or distributed.

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Q26). How will you calculate the total number of rows in a sequential file?

To calculate the total number of rows in a sequential file, we can use a system variable @INROWNUM

Q27). Define the usage analysis in DataStage.

The usage analysis can be performed in DataStage with few clicks only. For this purpose, launch the DataStage Manager first then right click on the job, select the usage analysis option and you are done.

Q28). What is the meaning of OConv () and IConv () functions in DataStage?

They are used to convert files one format to another. The OConv () function is used to convert the file for users to understand while IConv () function is used to convert the file for the system to understand. They are used to convert data in different formats, either it is ASCII code, numeric data, date, or time formats, etc.

Q29). How will you differentiate a Hash File and a Sequential File?

Hash files store data using Hash algorithms on Hash key values. It does not have any key value to store the data. Because of the Hash key feature in DataStage, search becomes faster for a Hash file as compared to a Sequential File.

Q30). How to clean a DataStage repository?

To clean a DataStage repository, you should clean up resources functionality in Database Manager.

Q31). How Operational DataStage (ODS) is different from a Data Warehouse?

ODS can be defined as the mini data warehouse that doesn’t store information for more than a year. At the same time, a Data Warehouse contains detailed information about the entire business.

Q32). Do you know how to drop the index before data is loaded to the target DataStage tool?

We can use Direct Load functionality to drop the index before data is loaded to the target DataStage tool.

Q33). What is the meaning of NLS in DataStage?

NLS means national language support that gives support for international languages like Spanish, German, Japanese, and more.

Q34). How DataStage supports slowly changing dimensions?

In DataStage 8.5 version, this function is available.

Q35). What is the process for finding bugs in a job sequence?

It can be done through the DataStage director.

Q36). Do you know any third-party tool that can be integrated with DataStage? Have you ever used it during your last job experience?

TNG, Autosys, and Even coordinator are a few third-party tools that can be used with DataStage. Yes, I have worked on all these three tools and having hands-on expertize with all of them.

Q37). How can complex jobs be implemented in DataStage to improve the performance?

You should not use more than 20 stages for each job to improve the performance. If the number goes higher than 20, it is better using another job in that case.

Q38). What is a project in DataStage?

To launch a DataStage client, you should connect to the DataStage project first. A DataStage project contains DataStage jobs, built-in DataStage components, and user-defined functions.

Q39). Name different types of hash files in DataStage.

There are two types of hash files in DataStage. These are static has files and dynamic hash files. A static hash file is used when a limited amount of data is loaded to the target database. A dynamic hash file is used when we don’t know the exact amount of data to be transferred to the target database.

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Q40). What do you understand by the term Meta Stage?

A Meta Stage is used to save the metadata that is further helpful for data analysis and data lineage.

Q41). Have you ever worked in a UNIX environment and why it is significant in DataStage?

Yes, I have the knowledge of UNIX environment, and it is significant in DataStage too because one has to write UNIX programs when required.

Q42). How are DataStage and DataStage TX are different?

DataStage is a tool from ETL and DataStage TX is a tool from EAI.

Q43). How will you define a surrogate key in DataStage?

A surrogate key is used to retrieve data faster. It uses indexes for retrieval operations.

Q44). What is transaction size and array size mean in DataStage?

Transaction size signifies the total number of rows written before records are committed to a table. Array size means the total number of rows written to and from a table.

Q45). Name a different type of views in a DataStage director?

Job View, Status view, and Log View.

Q46). How can we manage rejected rows in DataStage?

To manage rejected rows, constraints should be defined in DataStage. It would be great defining a temporary storage area for rejected rows in DataStage.

Q47). What is a DS Designer?

A DS manager is used to design the work area and add various links to it.

Q48). What do you understand by the terms Link collector and Link Partitioner in DataStage?

Link Partitioner is used to divide data into multiple logical units based on partitioning methods. Link collector is used for collecting data from different partitions to a single data and save it to the target database.

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Q49). How to compare the ODBC and DRS stage?

DRS is much faster than ODBS because it uses native databases for connectivity.

Q50). How to compare the BCP and Orabulk stages?

Orabulk is used to store voluminous data in one target table of Oracle database. A BCP stage is used to store voluminous data in one target table of Microsoft SQL Server.


Here, we have listed the top 50 DataStage Interview Questions and Answers to prepare you for the next DataStage you are planning to appear currently. These questions are prepared after deep researc, but you should not restrict yourself to limited knowledge. Before you start applying for interviews, you are recommended joining DataStage certification program at JanBask Training and be future-ready with ample job opportunities in DataStage domain.

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