IBM InfoSphere DataStage Interview Questions - Set D

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IBM InfoSphere DataStage Interview Questions

Set D



Boost your career with IBM InfoSphere DataStage, a powerful ETL tool used for data integration, transformation, and data warehousing. Our platform offers a comprehensive collection of DataStage interview questions and exam preparation materials, covering everything from basic concepts to advanced topics. Whether you're a beginner or an experienced professional, explore real-world scenarios, practical questions, and expert-level insights to confidently prepare for interviews and certification exams.


DataStage Interview Questions


Question 01:

What is a Sequential File Stage in IBM InfoSphere DataStage?
Answer:
It is a stage used to read data from or write data to flat files such as .csv, .txt, or fixed-width files.

Question 02:

What is a sequential file?
Answer:
A file where data is stored line by line in a sequence, usually in text format.

Question 03:

What are the two main operations of Sequential File Stage?
Answer:

  • Reading data (Source)
  • Writing data (Target)

Question 04:

How do you read data from a file?
Answer:
Use Sequential File Stage as a source, define file path, format, and column metadata.

Question 05:

How do you write data to a file?
Answer:
Use Sequential File Stage as a target and specify output file properties.

Question 06:

What file formats are supported?
Answer:

  • Delimited files (CSV, TSV)
  • Fixed-width files

Question 07:

What is a delimiter?
Answer:
A character used to separate columns (e.g., comma, tab, pipe).

Question 08:

Common delimiters used?
Answer:

  • Comma (,)
  • Tab (\t)
  • Pipe (|)

Question 09:

What is a header row?
Answer:
The first row containing column names.

Question 10:

How do you skip header rows?
Answer:
Use "Header rows" property and set number of rows to skip.

Question 11:

What is a footer row?
Answer:
Rows at the end of a file, usually containing summary or metadata.

Question 12:

How to skip footer rows?
Answer:
Use "Footer rows" property.

Question 13:

What is fixed-width file?
Answer:
A file where each column has a fixed number of characters.

Question 14:

How to define fixed-width columns?
Answer:
By specifying column offsets and lengths.

Question 15:

Difference between fixed-width and delimited file?
Answer:

  • Fixed-width: Position-based
  • Delimited: Separator-based

Question 16:

What is null field handling?
Answer:
Handling missing or empty values in input data.

Question 17:

What is "Final delimiter"?
Answer:
Specifies whether the last column also ends with delimiter.

Question 18:

What is "Quote character"?
Answer:
Used to enclose string values (e.g., "text").

Question 19:

What is "Escape character"?
Answer:
Used to treat special characters as normal text.

Question 20:

What is file encoding?
Answer:
Defines how data is stored (e.g., UTF-8, ASCII).

Question 21:

What is "First line is column names"?
Answer:
Option to treat first row as metadata instead of data.

Question 22:

What is "Read method"?
Answer:
Defines how file is read (Sequential, Parallel).

Question 23:

What is "Write method"?
Answer:
Defines how output file is written.

Question 24:

What is file update mode?
Answer:
Options for writing file:

  • Create
  • Append
  • Overwrite

Question 25:

What happens in "Overwrite"?
Answer:
Existing file is replaced.

Question 26:

What happens in "Append"?
Answer:
New data is added to existing file.

Question 27:

What is "Create (Error if exists)"?
Answer:
Job fails if file already exists.

Question 28:

What is "Use existing"?
Answer:
Uses existing file without modification.

Question 29:

What is reject link?
Answer:
A link that captures rejected records during processing.

Question 30:

Why use reject link?
Answer:
To handle bad or invalid records separately.

Question 31:

What causes records to be rejected?
Answer:

  • Data type mismatch
  • Format errors
  • Null constraint violations

Question 32:

What is error handling in Sequential Stage?
Answer:
Capturing invalid records and logging errors.

Question 33:

What is "Max errors"?
Answer:
Maximum allowed errors before job fails.

Question 34:

What is "Keep rejected rows"?
Answer:
Option to retain rejected records.

Question 35:

What is sed command?
Answer:
A Unix stream editor used to manipulate text data.

Question 36:

Why use sed in Sequential Stage?
Answer:
To filter or modify input data before processing.

Question 37:

Example of sed to get first row?
Answer:
sed -n '1p' file.txt

Question 38:

Example of sed to get last row?
Answer:
sed -n '$p' file.txt

Question 39:

Example to get specific row (e.g., 10th)?
Answer:
sed -n '10p' file.txt

Question 40:

Example to get range (5–10 rows)?
Answer:
sed -n '5,10p' file.txt

Question 41:

How to use sed in DataStage?
Answer:
Use it in "Filter command" property of Sequential File Stage.

Question 42:

What is filter command?
Answer:
A command used to preprocess input data before reading.

Question 43:

What is "File pattern"?
Answer:
Used to read multiple files using wildcard (*).

Question 44:

What is "File name column"?
Answer:
Stores file name from which data is read.

Question 45:

What is "Buffer size"?
Answer:
Defines memory used for reading/writing file.

Question 46:

What is "Record delimiter"?
Answer:
Defines how rows are separated (usually newline).

Question 47:

What is "Column delimiter"?
Answer:
Defines how columns are separated.

Question 48:

What is performance tip for Sequential File?
Answer:

  • Use proper buffer size
  • Avoid unnecessary sorting
  • Use parallel jobs

Question 49:

What is common issue with Sequential File Stage?
Answer:

  • Incorrect delimiter
  • Data type mismatch
  • Encoding issues

Question 50:

Best practices for Sequential File Stage?
Answer:

  • Always define metadata correctly
  • Use reject links
  • Avoid hardcoding file paths (use parameters)
  • Validate input files before processing


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