Top 50 Informatica Interview Questions You Must Prepare 24.Jun.2024

Q1. What Are The Differences Between Informatica Power Center Versions 6.2 And 7.1, Also Between Versions 6.2 And 5.1?

The main difference between informatica 5.1 and 6.1 is that in 6.1 they introduce a new thing called repository server and in place of server manager(5.1), they introduce workflow manager and workflow monitor.

Q2. Is A Fact Table Normalized Or De-normalized?

A fact table is always DENORMALISED table. It consists of data from dimension table (Primary Key's) and Fact table has foreign keys and measures.

Q3. What Is A Source Qualifier?

When you add a relational or a flat file source definition to a mapping, you need to connect it to a Source Qualifier trformation. The Source Qualifier represents the rows that the Informatica Server reads when it executes a session.

Q4. How Many Types Of Dimensions Are Available In Informatica?

The types of dimensions available are:

  1. Junk dimension
  2. Degenerative Dimension
  3. Conformed Dimension

Q5. At The Max How Many Trformations Can Be Us In A Mapping?

In a mapping we can use any number of trformations depending on the project, and the included trformations in the particular related trformations.

Q6. What Is The Difference Between Filter And Lookup Trformation?

  1. Filter trformation is an Active trformation and Lookup is a Passive trformation.
  2. Filter trformation is used to Filter rows based on condition and Lookup is used to look up data in a flat file or a relational table, view, or synonym.

Q7. How Can We Use pmcmd Command In A Workflow Or To Run A Session

By using command in the command task there is a option pression. we can write appropriate command of pmcmd to run workflow.

Q8. What Is Difference Between Informatica 7.1 And Abinitio?

There is a lot of difference between informatica and AbInitio:

  • In AbInitio we are using 3 parallelism but Informatica using 1 parallelism.
  • In Ab Initio no scheduling option we can schedule manually or pl/sql script but informatica contains 4 scheduling options.
  • In Ab Inition contains co-operating system but informatica is not.
  • Ramp time is very quickly in Ab Initio compare than Informatica.
  • Ab Initio is user friendly than Informatica.

Q9. When We Create A Target As Flat File And Source As Oracle. How Can I Specify First Rows As Column Names In Flat Files?

Use a pre sql statement., but this is a hard coding method. If you change the column names or put in extra columns in the flat file, you will have to change the insert statement.

You can also achieve this by changing the setting in the Informatica Repository manager to display the columns heading. The only disadvantage of this is that it will be applied on all the files that will be generated by this server.

Q10. How To Load Time Dimension?

We can use SCD Type 1/2/3 to load any Dimensions based on the requirement. We can also use procedure to populate Time Dimension

Q11. What Is Difference Between Maplet And Reusable Trformation?

Maplet :

  • one or more trformations.
  • set of trformations that are reusable.

Reusable trformation :

  • only one trformation
  • Single trformation which is reusable.

Q12. How To Import Oracle Sequence Into Informatica?

Create one procedure and declare the sequence inside the procedure, finally call the procedure in informatica with the help of stored procedure trformation.

Q13. How To Read Rejected Data Or Bad Data From Bad File And Reload It To Target?

Correction the rejected data and send to target relational tables using load order utility. Find out the rejected data by using column indicator and row indicator.

Q14. Compare Data Warehousing Top-down Approach With Bottom-up Approach.

Top down
ODS-->ETL-->Datawarehouse-->Datamart-->OLAP

Bottom up
ODS-->ETL-->Datamart-->Datawarehouse-->OLAP

Q15. What Is The Default Source Option For Update Strategy Trformation?

Default option for update strategy trformation is dd_insert or we can put '0' in session level data driven.

Q16. Why We Use Stored Procedure Trformation?

A Stored Procedure trformation is an important tool for populating and maintaining databases. Database administrators create stored procedures to automate time-consuming tasks that are too complicated for standard SQL statements.

Q17. What Are Main Advantages And Purpose Of Using Normalizer Trformation In Informatica?

Narmalizer Trformation is used mainly with COBOL sources where most of the time data is stored in de-normalized format. Also, Normalizer trformation can be used to create multiple rows from a single row of data.

  1. Normalizer Trformation read the data from COBOL Sources.
  2. It support Horizontal Pivot .It is a processing of single input into a multiple output

Q18. Which All Databases Powercenter Server On Windows Can Connect To?

PowerCenter Server on Windows can connect to following databases:

  1. IBM DB2
  2. Informix
  3. Microsoft Access
  4. Microsoft Excel
  5. Microsoft SQL Server
  6. Oracle
  7. Sybase
  8. Teradata

Q19. Which All Databases Powercenter Server On Unix Can Connect To?

PowerCenter Server on UNIX can connect to following databases:

  1. IBM DB2
  2. Informix
  3. Oracle
  4. Sybase
  5. Teradata

Q20. Define Informatica Repository?

The informatica repository is at the center of the informatica suite. You create a set of metadata tables within the repository database that the informatica application and tools access. The informatica client and server access the repository to save and retrieve metadata.

Q21. Which Is Better Among Connected Lookup And Unconnected Lookup Trformations In Informatica Or Any Other Etl Tool?

If you are having defined source you can use connected, source is not well defined or from different database you can go for unconnected.

Connected and unconnected lookup depends on scenarios and performance If you are looking for a single value for look up and the value is like 1 in 1000 then you should go for unconnected lookup. Performance wise its better as we are not frequently using the trformation. If multiple columns are returned as lookup value then one should go for connected lookup.

Q22. What Is The Difference Between Informatics 7x And 8x And What Is Latest Version?

Java Trformation available in the 8x version and it is not available in 7x version.

Q23. Differences Between Normalizer And Normalizer Trformation.

Normalizer : It is a trformation mainly using for cobol sources. It change the rows into columns and columns into rows.

Normalization : To remove the redundancy and inconsistency.

Normalizer Trformation : can be used to obtain multiple columns from a single row.

Q24. What Type Of Repositories Can Be Created Using Informatica Repository Manager?

Informatica PowerCenter includeds following type of repositories :

Standalone Repository : A repository that functions individually and this is unrelated to any other repositories.

Global Repository : This is a centralized repository in a domain. This repository can contain shared objects across the repositories in a domain. The objects are shared through global shortcuts.

Local Repository : Local repository is within a domain and it’s not a global repository. Local repository can connect to a global repository using global shortcuts and can use objects in it’s shared folders.

Versioned Repository : This can either be local or global repository but it allows version control for the repository. A versioned repository can store multiple copies, or versions of an object. This features allows to efficiently develop, test and deploy metadata in the production environment.

Q25. How To Get The First 100 Rows From The Flat File Into The Target?

create one procedure and declare the sequence inside the procedure, finally call the procedure in informatica with the help of stored procedure trformation.

Q26. What Is Difference Between Partitioning Of Relational Target And Partitioning Of File Targets?

Partition's can be done on both relational and flat files.
Informatica supports following partitions

  1. Database partitioning
  2. RoundRobin
  3. Pass-through
  4. Hash-Key partitioning
  5. Key Range partitioning

All these are applicable for relational targets. For flat file only database partitioning is not applicable.

Informatica supports Navy partitioning. you can just specify the name of the target file and create the partitions, rest will be taken care by informatica session.

Q27. Discuss The Advantages & Disadvantages Of Star & Snowflake Schema?

In a STAR schema there is no relation between any two dimension tables, whereas in a SNOWFLAKE schema there is a possible relation between the dimension tables.

In star schema there is no relationship between two relational tables. All dimensions are de-normalized and query performance is degrades. In this snow flake schema dimensions are normalized. In this SF schema table space is increased. Maintenance cost is high. Query performance is increased.

Q28. How Do You Handle Decimal Places While Importing A Flatfile Into Informatica?

while importing flat file definition just specify the scale for a numeric data type in the mapping, the flat file source supports only number datatype (no decimal and integer). In the SQ associated with that source will have a data type as decimal for that number port of the source.

source ->number datatype port ->SQ -> decimal datatype. Integer is not supported. hence decimal is taken care.

Import the field as string and then use expression to convert it, so that we can avoid truncation if decimal places in source itself.

Q29. How To Join Two Tables Without Using The Joiner Trformation?

Its possible to join the two or more tables by using source qualifier. But provided the tables should have relationship.

When you drag and drop the tables you will getting the source qualifier for each table. Delete all the source qualifiers. Add a common source qualifier for all. Right click on the source qualifier you will find EDIT click on it. Click on the properties tab, you will find sql query in that you can write your sqls.

You can also do it using Session --- mapping---source there you have an option called User Defined Join there you can write your SQL.

Q30. What Are The Methods For Creating Reusable Trformations?

There two methods for creating reusable trformations:

  1. Using trformation developer tool.
  2. Converting a non reusable trformation into a reusable trformation in mapping.

Q31. Difference Between Summary Filter And Details Filter?

Summary Filter - we can apply records group by that contain common values.

Detail Filter - we can apply to each and every record in a database.

Q32. What Can We Do To Improve The Performance Of Informatica Aggregator Trformation?

Aggregator performance improves dramatically if records are sorted before passing to the aggregator and "sorted input" option under aggregator properties is checked. The record set should be sorted on those columns that are used in Group By operation.

It is often a good idea to sort the record set in database level e.g. inside a source qualifier trformation, unless there is a chance that already sorted records from source qualifier can again become unsorted before reaching aggregator.

Q33. Doubts Regarding Rank Trformation: Can We Do Ranking Using Two Ports? Can We Rank All The Rows Coming From Source, How?

When ETL load the data from source we can declare the rank of the incoming data to pass a rank trformation. We can't declare two rank on a single source data. We can do rank the row by declaring the rank Trformation and declaring the rank port.

Q34. What Is The Router Trformation?

A Router trformation is similar to a Filter trformation because both trformations allow you to use a condition to test data. However, a Filter trformation tests data for one condition and drops the rows of data that do not meet the condition. A Router trformation tests data for one or more conditions and gives you the option to route rows of data that do not meet any of the conditions to a default output group.

If you need to test the same input data based on multiple conditions, use a Router Trformation in a mapping instead of creating multiple Filter trformations to perform the same task.

Q35. What Is A Code Page?

A code page contains encoding to specify characters in a set of one or more languages. The code page is selected based on source of the data. For example if source contains Japanese text then the code page should be selected to support Japanese text.

When a code page is chosen, the program or application for which the code page is set, refers to a specific set of data that describes the characters the application recognizes. This influences the way that application stores, receives, and sends character data.

Q36. How Can You Access The Remote Source Into Your Session?

Relational source : To access relational source which is situated in a remote place , you need to configure database connection to the datasource.

FileSource : To access the remote source file you must configure the FTP connection to the host machine before you create the session.

Heterogeneous : When you are mapping contains more than one source type, the server manager creates a heterogeneous session that displays source options for all types.

Q37. How Do I Import Vsam Files From Source To Target. Do I Need A Special Plugin

As far my knowledge by using power exchange tool convert VSAM file to oracle tables then do mapping as usual to the target table.

Q38. How Can You Complete Unrecoverable Sessions?

Under certain circumstances, when a session does not complete, you need to truncate the target tables and run the session from the beginning. Run the session from the beginning when the Informatica Server cannot run recovery or when running recovery might result in inconsistent data.

If there is no recovery mode on in session and workflow failed in mid of execution then

  1. Don’t truncate table immediately.
  2. If there is large volume of data is performing by the load and more than 25% data has loaded then-if same workflow has multiple session then check particular session which caused to be failed and fire the delete command only to delete particular session data which has loaded and copy the session into new workflow and run only that session or dependent others.

Q39. How Can We Partition A Session In Informatica?

The Informatica PowerCenter Partitioning option optimizes parallel processing on multiprocessor hardware by providing a thread-based architecture and built-in data partitioning.

GUI-based tools reduce the development effort necessary to create data partitions and streamline ongoing troubleshooting and performance tuning tasks, while ensuring data integrity throughout the execution process. As the amount of data within an organization expands and real-time demand for information grows, the PowerCenter Partitioning option enables hardware and applications to provide outstanding performance and jointly scale to handle large volumes of data and users.

Q40. Explain Use Of Update Strategy Trformation?

To flag source records as INSERT, DELETE, UPDATE or REJECT for target database. Default flag is Insert. This is must for Incremental Data Loading.

This is the important trformation,is used to maintain the history data or just most recent changes into the target table.

We can set or flag the records by using these two levels.

  1. Within a session :
    When you configure the session,you can instruct the informatica server to either treat all the records in the same way.
  2. Within a mapping :
    within a mapping we use update strategy trformation to flag the records like insert,update,delete or reject.

Q41. How Do We Estimate The Number Of Partitions That A Mapping Really Requires? Is It Dependent On The Machine Configuration?

It depends upon the informatica version we are using. suppose if we are using informatica 6 it supports only 32 partitions where as informatica 7 supports 64 partitions.

Q42. What Is The Use Of Incremental Aggregation? Explain Me In Brief With An Example.

Its a session option, when the informatica server performs incremental aggr. it passes new source data through the mapping and uses historical cache data to perform new aggregation calculations incrementally for performance we will use it.

When using incremental aggregation, you apply captured changes in the source to aggregate calculations in a session. If the source changes incrementally and you can capture changes, you can configure the session to process those changes. This allows the Integration Service to update the target incrementally, rather than forcing it to process the entire source and recalculate the same data each time you run the session.

Q43. If You Want To Create Indexes After The Load Process Which Trformation You Choose?

Its usually not done in the mapping (trformation) level. Its done in session level. Create a command task which will execute a shell script (if Unix) or any other scripts which contains the create index command. Use this command task in the workflow after the session or else, You can create it with a post session command.

Q44. Explain About Informatica Server Architecture?

Informatica server, load managers, data trfer manager, reader, temp server and writer are the components of informatica server. first load manager sends a request to the reader if the reader is ready to read the data from source and dump into the temp server and data trfer manager manages the load and it send the request to writer as per first in first out process and writer takes the data from temp server and loads it into the target.

Q45. How The Informatica Server Increases The Session Performance Through Partitioning The Source?

For a relational sources informatica server creates multiple connections for each partition of a single source and extracts separate range of data for each connection.

Informatica server reads multiple partitions of a single source concurrently. Similarly for loading also informatica server creates multiple connections to the target and loads partitions of data concurrently.

For XML and file sources, informatica server reads multiple files concurrently. For loading the data informatica server creates a separate file for each partition (of a source file). You can choose to merge the targets.

Q46. How Do You Configure Mapping In Informatica?

  • Import src from database.
  • Check if target table already exists in database.
  • If it exists make sure u delete data from it and import into designer.
  • Or else create it with create target wizard.
  • Now you can drag needed trformations into the workspace.
  • Use them according to your purpose.

For improved performance follow these tips:-

  • Use sorter before aggregator
  • If filter is used keep it as near to the source as possible.
  • If possible use an extra expression tr before target to make corrections in future.
  • Enable sorted input option if sorter is used before agg tr.
  • If more filters are needed use router tr.
  • you can use source filter option of SQ if filter tr is immediately after source.
  • In case of router if not needed do not connect default group to any target.

Q47. What Is The Default Join That Source Qualifier Provides?

Inner equi join.

Q48. Can You Start A Batches With In A Batch?

You cannot. If you want to start batch that resides in a batch, create a new independent batch and copy the necessary sessions into the new batch.

Q49. What Are The Joiner Caches?

Specifies the directory used to cache master records and the index to these records. By default, the cached files are created in a directory specified by the server variable $PMCacheDir. If you override the directory, make sure the directory exists and contains enough disk space for the cache files. The directory can be a mapped or mounted drive. There are 2-types of cache in the joiner:

  1. Data cache
  2. Index Cache

Q50. What Is Hash Table Informatica?

In hash partitioning, the Informatica Server uses a hash function to group rows of data among partitions. The Informatica Server groups the data based on a partition key.Use hash partitioning when you want the Informatica Server to distribute rows to the partitions by group. For example, you need to sort items by item ID, but you do not know how many items have a particular ID number.