Informatica PowerCenter, called Informatica for short, is an ETL (extraction, transformation, and loading) tool that’s widely used in building enterprise data warehouses. According to iDataLabs, more than 21,000 companies in the U.S. and elsewhere use Informatica, such as the U.S. Air Force, the Chicago Cubs, and eBay—in fact, many companies on the Fortune 100 list use Informatica.
According to Glassdoor, the average salary for an Informatica professional services senior consultant is $111,375, plus more than $16,000 in additional pay. And with businesses around the world in such a wide range of fields using Informatica—including financial services, healthcare, the nonprofit sector, manufacturing, insurance, and publishing—the number of needed Informatica professionals can only be expected to grow in the future.
Wondering what Informatica questions you might be asked in an interview? Here we’ll tell you the top Informatica interview questions and answers, at both the basic and expert level, to help you prepare for that higher-paying job.
Top Informatica Interview Questions and Answers
1. What are the advantages of Informatica over other ETL tools?
Informatica is the world’s most popular data integration tool. It interoperates with the widest range of different standards, systems, and applications; it’s fast; and it is designed to adapt to the constant change in the field/market, the organization, and the system. Also, you can easily monitor jobs, and it’s easy to identify the causes of failed jobs.
2. What are the main components of Informatica?
The main features of Informatica are the client tools/applications, server, repository server, and repository.
3. What can Informatica be used for in an organization?
Informatica can be used for data migration—for example, a company is transitioning from an older mainframe system to a new database system; data warehousing—an ETL tool would be needed for moving data from the production system to the warehouse; data integration—incorporating data from multiple databases or file-based systems, for example; and cleaning up data.
4. What is an enterprise data warehouse?
An enterprise data warehouse is a single unified database that holds an organization’s business information and distributes it throughout the company. There are variations, but it likely includes a unified approach to sorting and presenting data, and data can be classified and accessed according to the subject.
5. Describe an Informatica workflow.
In the workflow manager, you build a workflow by logically connecting tasks to execute code (for example, scripts). The final workflow will automatically run all the tasks within it in the specified order.
6. What is the domain?
A domain is composed of relationships and nodes covered by one organizational point.
7. What are some of the types of transformation?
Some transformation types are aggregator, expression, filter, joiner, lookup, rank, router, and normalizer.
8. What’s the difference between active and passive transformation?
An active transformation can change the number of rows that pass through it, can change the transaction boundary and can change the actual row type. A passive transformation doesn’t change either the number of rows that pass through it or the row type and doesn’t change the transaction boundary.
9. Why might router transformation be better than filter transformation?
With router transformation, you can have better performance, and it’s less complex and more efficient than filter transformation.
10. Why would you want to partition a section?
It improves the server’s efficiency; other transformations are carried out in parallel.
11. What’s the difference between a mapping parameter and a mapping variable?
Mapping variables, as the name implies, are values that change during a session’s execution. Values that don’t change are called parameters.
12. How would you self-join in an Informatica mapping?
To self-join, place one transformation minimum between the source qualifier and the joiner in one branch minimum. You must pre-sort the data and then configure the joiner to accept sorted input.
13. What are the different join types within a joiner transformation?
There are four join types: normal join, master outer join, detail outer join and full outer join.
14. What are the different dimensions in Informatica?
Three dimensions are available in Informatica: junk, degenerative and conformed.
15. What is the difference between a session and a batch?
A session is a set of commands by which the server moves data to the target. A batch is a set of individual tasks.
16. How many sessions can be grouped in a batch?
There is no limit to the number of sessions that can comprise a batch. But the fewer the sessions, the easier the migration.
17. Describe the modes of data movement.
In the normal mode of data movement, a separate DML stmt is prepared and executed. In the bulk mode, a DML stmt is prepared and executed for multiple records at a time, improving efficiency.
18. What is the aggregator cache used for?
It stores transitional files found in the local buffer memory, and stores transformation values if extra memory is required.
19. What is the persistent lookup cache?
This data is stored on the server, saving time because a database query doesn’t need to happen when a lookup occurs.
20. What are Mapplets?
In the Mapplet Designer, you create mapplets, which are reusable objects that contain a set of transformations.
21. Describe the differences between a mapplet and a mapping.
Mapplets contain only transformations, can be reused and are developed for complex calculations. Mappings include source, target, and transformations; they are not reusable; and are used for less complex calculations than mapplets, such as for what data to move to a target.
22. How does a pipeline partition improve performance?
A pipeline partition lets you divide a pipeline into different reader/transformation/writer threads. The integration service can run the different partitions within the mapping at the same time, increasing efficiency.
23. What are some other types of partitioning aside from pipeline partitioning?
Other types of partitioning include database partitioning, round-robin partitioning, key-range partitioning, pass-through partitioning, hash user-keys partitioning and hash auto-keys partitioning.
24. Describe the differences between an SQL override and a lookup override.
When you want to limit the number of rows entering a mapping pipeline, you’d use an SQL override. When you want to limit the number of lookup rows to avoid scanning an entire table, you’d use the lookup override. Lookup override provides only one record even if multiple records for a condition exist. Also, SQL override doesn’t use the “order by” clause—you have to manually enter it in the query.
25. What are the configurable commit types?
There are three configurable commit types: target-based, source-based and user-defined.
26. What is ETL (Extract, transform, Load) and write some ETL tools?
ETL stands for Extract, Transform, and Load. It is a process used to move data from one or more sources to a destination database, data warehouse, or other data repository.
27. What is Informatica PowerCenter?
Write its components. Informatica PowerCenter is a data integration tool used for extracting, transforming, and loading data from various sources to a target system.
28. Write the difference between connected lookup and unconnected lookup.
A connected lookup refers to a lookup transformation that is linked to the pipeline flow, whereas an unconnected lookup is a standalone transformation that is not linked to the pipeline flow. A connected lookup retrieves data from the lookup table and passes it on to the next transformation in the pipeline, while an unconnected lookup can be called within another transformation to return a value.
29. An unconnected lookup can have how many input parameters?
An unconnected lookup can have one or more input parameters.
30. Name the output files that are created by the Informatica server at runtime.
The Informatica server creates log files, workflow log files, and session files at runtime.
31. Can we store previous session logs in Informatica?
If yes, how? Yes, we can store previous session logs in Informatica. This can be done by configuring the session to log all events and then saving the log files to a designated location for future reference.
32. Explain data driven sessions.
Data-driven sessions are Informatica sessions that are executed based on the data available in a specified file or table. This allows for the automatic execution of sessions without manual intervention, as the session is triggered based on the data available.
33. What is the target load order?
Target load order is the order in which the Informatica server inserts data into the target tables. The target load order can be specified in the session properties to ensure that data is inserted into the target tables in a specific sequence.
34. What is the role of a repository manager?
The role of a repository manager in Informatica is to manage the PowerCenter Repository, including creating and maintaining the repository, managing user access, and backing up and restoring the repository.
35. What are the different ways of parallel processing?
Different ways of parallel processing include:
- Multi-threading: breaking down a task into multiple smaller tasks that can be executed simultaneously by different threads.
- Multi-processing: executing multiple tasks simultaneously by dividing the work between various processors.
- Distributed processing: breaking down a task into smaller tasks and distributing them across multiple systems for processing.
36. What is OLAP, and write its type?
OLAP (Online Analytical Processing) is a data analysis technology that provides multidimensional business data analysis. There are three types of OLAP:
- Relational OLAP (ROLAP)
- Multidimensional OLAP (MOLAP)
- Hybrid OLAP (HOLAP)
37. What is the scenario in which the Informatica server rejects files?
The Informatica server may reject files for a few reasons, including:
- The file format is not supported
- The file size exceeds the limit set by the Informatica administrator
- The file contains incorrect or corrupted data
38. What do you mean by surrogate key?
A surrogate key is a unique identifier generated by the system to replace the natural primary key of a table. The main purpose of a surrogate key is to provide a stable, unique identifier for a record, even if the natural primary critical changes over time.
39. Give a few mapping design tips for Informatica.
A few mapping design tips for Informatica include:
- Use source-based or incremental loading whenever possible to reduce the amount of data processed.
- Use the appropriate transformation for the task, as some changes are more efficient than others.
- Use caching where applicable, as this can reduce the number of database hits and improve performance.
- Minimize the number of changes in a mapping, as each transformation adds overhead to the processing time.
40. How can we improve the performance of Informatica Aggregator Transformation?
To improve the performance of Informatica Aggregator Transformation, the following tips can be used:
- Filter data before the Aggregator Transformation to reduce the amount of data processed.
- Use indexing to improve the performance of database lookups.
- Use memory or disk-based aggregation, depending on the amount of data being processed.
- Use partitioning to split the data into smaller chunks for processing.
Informatica Interview Questions for Experienced
41. What are different lookup caches?
The different lookup caches in Informatica include:
- Persistent cache: A cache stored on a disk can be reused across multiple sessions.
- Dynamic cache: A cache that updates its data based on the input data for each session.
- Static cache: A cache that holds a predetermined data set and does not change during the session.
- Reusable cache: A cache can be reused across multiple mappings in a mapping or different mappings.
42. What is the difference between static and dynamic cache?
The difference between static and dynamic cache is that it holds a predetermined data set and does not change, while dynamic cache updates its data based on the input data.
43. What is the pm cmd command? How to use it?
Pmcmd command is a command-line tool used for controlling Informatica PowerCenter services. It can start and stop workflows, sessions, and other tasks. To use pm cmd, you need to specify the command, service, and options in the command line.
44. What do you mean by mapplet in Informatica?
A mapplet in Informatica is a reusable object that contains a set of transformations. Therefore, it can be used as a mapping building block and helps simplify the mapping development process.
45. What is the difference between Router and Filter?
Router and Filter are two different types of transformations in Informatica. A Router is used to route data to multiple output ports based on conditions defined in the change, while a Filter is used to eliminate rows based on requirements specified in the transformation.
46. Explain the tracing level.
Tracing level refers to the level of detail in the log files generated during the execution of a workflow. There are five tracing levels in Informatica, ranging from low to high, and they determine the amount of information logged during the execution of the workflow. The higher the tracing level, the more information is logged, but the slower the workflow execution time.
47. Write the difference between stop and abort options in the workflow monitor.
The stop option in the workflow monitor pauses the execution of a task or the entire workflow, allowing the user to resume it later. On the other hand, the abort option terminates the execution of a job or the whole workflow immediately without allowing for resumption.
48. What is DTM (Data Transformation Manager) Process?
DTM, or Data Transformation Manager, is a component of Informatica that manages the execution of data transformation tasks within a workflow. The DTM process loads data into memory, applies transformation rules and writes the transformed data to a target database or file.
49. What are the components of a workflow manager in Informatica?
The components of a workflow manager in Informatica include tasks, worklets, workflows, and workflow monitoring. Tasks are the individual work units executed within a workflow, such as data extraction or transformation. Worklets are reusable collections of tasks. Workflows are tasks and workouts performed to complete a specific process. Finally, the workflow monitor is the interface for monitoring and controlling the execution of workflows.
50. What are the different types of tasks in Informatica?
The different types of tasks in Informatica include data extraction, data transformation, data loading, email, event wait, command, and session.
51. What do you mean by incremental loading in Informatica?
Incremental loading in Informatica refers to only extracting and transforming new or changed data rather than processing all data every time a workflow runs. This method optimizes performance and reduces processing time for large data sets.
52. Explain complex mapping and write its features.
Complex mapping in Informatica is a type of data transformation that involves multiple sources and complex calculations. Its features include performing changes using various sources, calculating large amounts of data, and handling complex data relationships.
53. What do you mean by the star schema?
The star schema is a type of data modeling in which data is organized into a central fact table surrounded by dimension tables. This schema is used in data warehousing to provide a simple and efficient way to query and analyze large amounts of data. The star schema allows for rapid and easy data aggregation, making it a popular choice for business intelligence and data analysis.
Tips to Prepare for Informatica Interview
- Familiarize yourself with Informatica products and features: Before appearing for the interview, it's essential to have a good understanding of Informatica products, features, and their use cases.
- Brush up on data warehousing concepts: Informatica is primarily used for data warehousing and business intelligence, so ensure you have a solid understanding of concepts such as star schema, ETL, and data modeling.
- Get hands-on experience with Informatica tools: Practical experience is vital in preparing for an interview. Try to work on real-world projects and get hands-on experience with Informatica tools like PowerCenter, Data Quality, and MDM.
- Brush up on SQL and database concepts: Understanding SQL and database concepts is crucial for Informatica interviews. Brush up on relational database management, SQL queries, and database design.
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If you have any questions or queries, feel free to post them in the comments section below. Our team will get back to you at the earliest.
1. How many rounds are there in an Informatica interview?
The number of rounds in an Informatica interview can vary depending on the company.
2. Is Informatica a good career choice?
It depends on your career goals and interests.
3. Is Informatica difficult to learn?
It can be challenging, but with dedication and practice, anyone can learn it.
4. How can I prepare for Informatica?
Practicing Informatica tools and familiarizing yourself with data warehousing concepts can help.
5. What do you know about Informatica?
Informatica is a popular ETL (Extract, Transform, Load) tool for data integration and management.
6. How many days will it take to learn Informatica?
Learning Informatica varies for each individual, but it usually takes several weeks to a few months to get a basic understanding.
7. Does Informatica have a future?
Informatica is a widely used tool with strong market demand, so it has a bright future.