25 Informatica Interview Questions and Answers

Informatica is a leading data integration tool widely used for data warehousing, data migration, and data transformation projects. Its robust capabilities in handling large volumes of data and seamless integration with various data sources make it a preferred choice for organizations aiming to streamline their data management processes. Informatica’s user-friendly interface and powerful ETL (Extract, Transform, Load) functionalities enable efficient data processing and ensure data quality and consistency.

This article offers a curated selection of interview questions designed to test your knowledge and proficiency in Informatica. By reviewing these questions and their detailed answers, you will be better prepared to demonstrate your expertise and problem-solving abilities in Informatica during your interview.

Informatica Interview Questions and Answers

1. Describe the role of a Source Qualifier Transformation.

A Source Qualifier Transformation in Informatica is an active transformation that represents the rows the Integration Service reads from a source during a session. It performs tasks such as converting source data types to Informatica native data types, filtering rows, joining data from the same source database, sorting data, and selecting distinct values. It ensures that data read from the source is in the correct format and meets necessary criteria before further processing in the ETL pipeline.

2. What is a Session in Informatica?

A session in Informatica is a set of instructions that tells the Informatica server how and when to move data from sources to targets. It is a task created in the Workflow Manager to run a mapping, responsible for extracting, transforming, and loading data. Sessions can run in different modes, be scheduled, and provide options for error handling, logging, and performance tuning.

3. Describe the use of Aggregator Transformation.

Aggregator Transformation in Informatica performs aggregate calculations on groups of data, such as sum, average, count, min, and max. It groups data based on specified group-by ports and performs calculations on these groups. Key features include group-by, aggregate functions, sorted input for performance, and conditional aggregation for customized calculations.

4. What is a Router Transformation?

Router Transformation in Informatica is an active transformation that routes data into multiple transformations or targets based on specified conditions. It is more powerful than a Filter Transformation, as it can test multiple conditions and route data to different paths. It has input and output groups, with user-defined and default output groups for data that doesn’t meet any conditions.

5. How do you perform Error Handling in Informatica?

Error handling in Informatica involves identifying, capturing, and managing errors during the ETL process. Methods include session log files, error tables, reject files, error handling functions, exception handling in mappings, and workflow and session properties configuration.

6. How do you optimize a mapping for performance?

Optimizing a mapping for performance in Informatica involves strategies like source and target optimization, efficient transformations, session configuration, pushdown optimization, data caching, and incremental loading. These focus on improving data processing efficiency.

7. Describe the use of Joiner Transformation.

Joiner Transformation in Informatica allows joining data from two different sources, supporting various types of joins like normal, master outer, detail outer, and full outer. It is useful for heterogeneous sources and allows complex join conditions. Performance considerations include using sorted input and choosing the smaller dataset as the master source.

8. What is a Dynamic Lookup Cache?

A Dynamic Lookup Cache in Informatica allows the lookup cache to be updated dynamically as rows are processed, ensuring it contains the most recent data. It is useful for scenarios with frequently changing data, maintaining data consistency, and reducing the need for reloading the entire lookup table.

9. How do you use the Rank Transformation?

Rank Transformation in Informatica identifies top or bottom performers in a dataset based on specific criteria. It ranks data by specified columns and order, and you can set the number of ranks to generate. It is useful for tasks like finding top N customers or products.

10. How do you implement Slowly Changing Dimensions (SCD)?

Slowly Changing Dimensions (SCD) manage and track changes in dimension data over time. Types include SCD Type 0 (Fixed Dimension), Type 1 (Overwrite), Type 2 (Add New Row), Type 3 (Add New Column), Type 4 (History Table), and Type 6 (Hybrid). In Informatica, SCDs can be implemented using transformations like Lookup, Update Strategy, and Router.

11. Describe the use of Update Strategy Transformation.

The Update Strategy Transformation in Informatica controls how rows in a target table are processed, specifying whether rows should be inserted, updated, deleted, or rejected based on conditions. It uses constants like DD_INSERT, DD_UPDATE, DD_DELETE, and DD_REJECT to determine operations.

12. What is a Mapplet?

A Mapplet in Informatica is a reusable object that encapsulates a set of transformations, allowing for consistent and simplified maintenance across multiple mappings. Changes to a Mapplet are automatically reflected in all mappings that use it, ensuring consistent transformation logic.

13. How do you use the Expression Transformation?

The Expression Transformation in Informatica performs row-wise data manipulation, allowing calculations within a single row before writing to the target. It is used for data cleansing and manipulation tasks, such as concatenating fields, performing arithmetic operations, or applying conditional logic.

14. Explain the concept of Pushdown Optimization.

Pushdown Optimization in Informatica refers to pushing transformation logic to the source or target database, utilizing the database’s processing capabilities. It reduces data transfer between the Informatica server and the database, improving performance.

15. How do you handle Flat File Sources?

In Informatica, handling flat file sources involves defining the file structure, importing the file, configuring the session, and mapping the data. This process ensures that data from flat files is correctly integrated into the ETL workflow.

16. Describe the use of Sequence Generator Transformation.

The Sequence Generator Transformation in Informatica generates unique numeric values for creating primary keys, surrogate keys, or other unique identifiers. It has two main output ports: NEXTVAL for the next value in the sequence and CURRVAL for the current value.

17. What is a Control Task?

A Control Task in Informatica controls the execution of a workflow, defining conditions and actions that determine the workflow’s flow. It manages dependencies and ensures tasks are executed in the correct order.

18. How do you use the Union Transformation?

The Union Transformation in Informatica merges data from multiple sources into a single pipeline, similar to the SQL UNION operation. It combines data from different pipelines into one, ensuring seamless data flow through the integration process.

19. Explain the concept of Data Masking.

Data masking protects sensitive information by replacing it with fictional but realistic data. Techniques include static, dynamic, and on-the-fly data masking, using methods like substitution, shuffling, encryption, and nulling out.

20. Describe the use of Normalizer Transformation.

The Normalizer Transformation in Informatica converts a single row into multiple rows, useful for normalizing denormalized data structures. It is beneficial for detailed analysis or reporting on individual values stored in a denormalized format.

21. What is a Command Task?

A Command Task in Informatica executes shell commands, scripts, or batch files during workflow execution. It automates operations outside of Informatica, such as file manipulations, database operations, or invoking external scripts.

22. How do you use the Transaction Control Transformation?

The Transaction Control Transformation in Informatica defines and controls transaction boundaries within a mapping, allowing for commit or rollback transactions based on conditions. It provides granular control over data processing.

23. Explain the concept of Metadata Manager.

Metadata Manager in Informatica provides a centralized repository for metadata, enabling users to manage and govern data assets effectively. It offers features like metadata discovery, lineage and impact analysis, data governance, collaboration, and reporting and visualization tools.

24. What techniques do you use for performance tuning in Informatica?

Performance tuning in Informatica involves techniques like optimizing source and target databases, efficient use of transformations, partitioning, session and workflow configuration, pushdown optimization, and incremental loading to ensure efficient data integration processes.

25. What security features does Informatica provide to protect data?

Informatica provides security features to protect data, including authentication and authorization, data encryption, secure communication, data masking, audit trails, and policy management. These features safeguard sensitive information throughout the data integration process.