Infosys Senior Datastage Developer Interview Questions and Answers

ETL Developers are responsible for designing, developing, and maintaining ETL processes to extract, transform, and load data from various sources into a data warehouse.

• Designing ETL processes to extract data from multiple sources

• Transforming data to meet business requirements

• Loading data into a data warehouse or other target systems

• Developing and maintaining ETL jobs using tools like Informatica, Talend, or SSIS

SCD Type 1 in IICS involves overwriting existing data with new data without maintaining historical changes.

• In IICS, use the Mapping Designer to create a mapping that loads data from source to target.

• Use a Lookup transformation to check if the record already exists in the target table.

• If the record exists, update the existing record with new data using an Update Strategy transformation.

• If the record does not exist, inse...read more

Analytical functions are used to perform calculations across a set of rows related to the current row.

• Analytical functions operate on a group of rows and return a single result for each row

• They can be used to calculate running totals, moving averages, rank, percentiles, etc.

• Examples include ROW_NUMBER(), RANK(), SUM() OVER(), AVG() OVER()

The Slowly Changing Dimension Type 2 (SCD2) transformation is used for handling historical data changes in a data warehouse.

• SCD2 transformation is used to track historical changes in dimension tables.

• It maintains multiple versions of a record by adding new rows with updated information and end-dating the previous record.

• Commonly used in scenarios where historical data needs to be preserved and queried.

• Example: When a c...read more

To find the count of different types of joins between two tables A and B.

• Left join: Includes all records from table A and matching records from table B.

• Right join: Includes all records from table B and matching records from table A.

• Inner join: Includes only the matching records from both tables.

• Full outer join: Includes all records when there is a match in either table A or table B.

Start up parameters are used to configure the behavior of SQL Server when it starts up.

• Start up parameters are specified in the SQL Server Configuration Manager.

• Common start up parameters include -d (database files location), -e (error log location), -m (single user mode), -T (trace flags), etc.

• Start up parameters can be modified to customize the behavior of SQL Server during startup.

• Example: -dC:\Program Files\Microso...read more

Join is used to combine rows from two or more tables based on a related column, while lookup is used to retrieve data from a reference table based on a matching key.

• Join combines rows from multiple tables based on a related column

• Lookup retrieves data from a reference table based on a matching key

• Join can result in duplicate rows if there are multiple matches, while lookup returns only the first matching row

• Join is use...read more

Fact table contains quantitative data and measures, while dimension table contains descriptive attributes.

• Fact table contains numerical data that can be aggregated (e.g. sales revenue, quantity sold)

• Dimension table contains descriptive attributes for analysis (e.g. product name, customer details)

• Fact table is typically normalized, while dimension table is denormalized for faster queries

• Fact table is usually larger in s

Use sed command to display the line before a specific pattern

• Use 'sed -n '/pattern/{g;1!p;};h' file.txt' to display the line before the pattern

• Replace 'pattern' with the specific pattern you are looking for

• This command will display the line before the pattern in the file

I joined inm because of the company's reputation for innovation and growth in the tech industry.

• Attracted to company's reputation for innovation

• Excited about opportunities for growth in tech industry

• Impressed by company culture and values

List is an ordered collection of elements with duplicates allowed, while set is an unordered collection of unique elements.

• List maintains the order of elements, while set does not guarantee any specific order.

• List allows duplicate elements, while set does not allow duplicates.

• Example: List - [1, 2, 3, 1], Set - {1, 2, 3}

Optimizing PySpark involves tuning configurations, using efficient transformations/actions, and leveraging caching.

• Tune PySpark configurations for optimal performance (e.g. adjusting memory settings, parallelism)

• Use efficient transformations/actions to minimize unnecessary data shuffling (e.g. using narrow transformations like map instead of wide transformations like groupByKey)

• Leverage caching to persist intermediate

SOLID principles are a set of five design principles in object-oriented programming to make software designs more understandable, flexible, and maintainable.

• S - Single Responsibility Principle: A class should have only one reason to change.

• O - Open/Closed Principle: Software entities should be open for extension but closed for modification.

• L - Liskov Substitution Principle: Objects of a superclass should be replaceable...read more