Informatica interview questions and answers part 7

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45. How does the recovery mode work in informatica?
 Ans - In case of load failure an entry is made in OPB_SERV_ENTRY(?) table from where the extent of loading can be determined.

46.How do you measure session performance?
Ans -This can be done by check marking Collect performance Data check box.

47.Can we use Reusable Sequence Generator transformation in Mapplet?
Ans - No this cannot be done.

48.What is the difference between Filter transformation and Router transformation?
Ans - Filter transformation drops the data that do not meet the condition while latter captures the data even though the condition is not met and saves it in Default output group.

49.What is SQL override?
Ans - SQL override means overriding SQL in source qualifier or lookup for additional logic.

50.What are the types of data movement in Informatica server?
Ans - The two types of modes in Informatica are s below -
         1.Ascii mode    2. Unicode mode

51.How can PL/SQL script can be executed from Informatica mapping?
Ans - Stored Procedure transformation can be used to execute PL/SQL Scripts from informatica mapping.

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Informatica interview questions and answers part 6

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38.What are Stored Procedure transformation?

Ans- Stored Procedure transformation is an Passive & Connected or UnConnected transformation. It is useful to automate time-consuming tasks and in error handling, to drop and recreate indexes.

39. What is a source qualifier?

Ans- Source Qualifier represents the rows that the PowerCenter Server reads from a relational or flat file source when it runs a session. 

40. How a transformation be defined?
Ans-  A transformation is a repository object that generates, modifies, and passes data. The Designer provides a set of transformations that perform specific functions 

41. What are different types of transformations available in Informatica?

Ans - Aggregator, Application Source Qualifier, Custom, External Procedure , Expression, Filter, Input, Joiner, Lookup, Normalizer, Output, Rank, Router,  Sequence Generator,  Sorter, Stored Procedure , Source Qualifier ,   Transaction Control,    Update Strategy,  Union,  XML Source Qualifier ,  XML Generator,  XML Parser

42.What is Surrogate Key?
Ans - Surrogate key is a key that is maintained within the data warehouse instead of key taken from source data systems.

43. What are the types of OLAP?

Ans - 1. ROLAP (Relational OLAP) 2. MOLAP (Multidimensional OLAP) 3. HOLAP (Hybrid OLAP)

44. What is ROLAP

Ans ROLAP stands for Relational OLAP. Users see their data organised in cubes and dimensions but the data is stored in RDBMS.

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Informatica interview questions and answers part 5

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31. What is a target load order?
Ans: Target load order is specified on the basis of source qualifiers in a mapping. In case if there are multi-fold source qualifiers linked to different targets then one can entitle order in which informatica server loads data into targets.

32.What is power center repository?
Ans -The PowerCenter repository is used to share metadata across repositories to create a data mart domain.

33.What is fact table?

Ans -Fact table is the centralised table in a star schema.

34. What are the different types of fact tables?

Ans - Fact tables are of three types
    1. Additive
    2. Non-additive

    3. Semi additive

35. How can you define user defied event?

Ans - User defined event is a flow of tasks in the workflow. Events can be created and then raised as needed.

36.What is reusable transformation?
A. Reusable transformations can be used multiple times in a mapping. The reusable transformation is stored as a metadata separate from any other mapping that uses the transformation.

37.What is Dual table?

Ans - It is a table that is created by oracle along with data dictionary. 

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Informatica interview questions and answers part 4

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24. In how many ways can you add ports?
Ans - Ports can be added using 2 ways

• From other transformation
• Click on add port button

25.What are the two modes of data movement in Informatica Server?
Ans - There are 2 modes of data movement in informatica server 1. Normal Mode 2. Bulk Mode

26. What is Normal mode of data movement in Informatica Server?

Ans -  Normal Mode is a mode in which for every record a separate DML statement is prepared and executed.

27.  What is Normal mode of data movement in Informatica Server?

Ans - Bulk Mode s a mode in which for multiple records DML statement is prepared and executed thus improves performance.

28.What is the use of target designer?

Ans - target designer is used to create Target Definition.

29.What are the different types of Lookup Cache?
Ans - Following are the different types of lookup cache

• Recache from database
• Static cache
• Shared cache
• Dynamic cache
• Persistent cache

30.What are the two types of processes that run the session?
Ans - The two types of processes that run the session are
         1.Load Manager
         2. Data Transformation Manager processes

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Informatica interview questions and answers part 3

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15. What are the differences between varchar and varchar2?
Ans - They are both variable length data types. Varchar datatype has a size of 2000 bytes and varchar2 has a size of 4000 bytes. varchar is in ascii format while varchar2 is in unicode format

16. How can repository reports be accessed without SQL or other transformations?

Ans: There is no need of SQL or other transformation since it is a web app. Repository reports are established by metadata reporter.

17. What is the difference between global index and local index?
Ans - Global index is a single index covering all partitions and local index has separate index for each partition.

18.What is Rank transformation?
Ans - Rank transformation is an Active and Connected transformation. It is used to select the top or bottom rank of data.

 

19.What are Normaliser transformation?

Ans -  Normaliser Transformation is an Active and Connected transformation. It is used with COBOL sources where most of the time data is stored in denormalised format. It can be used to create multiple rows from a single row of data.

21.What are the features of complex mapping?
Ans - Difficult requirements,Many numbers of transformations,Complex business logic

22.What is Session?
Ans - A session is a group of commands that describes the server to move data to the target.
 

23. What is a Batch?

Batch: A Batch is group of tasks that includes one or more number of tasks.

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Informatica interview questions and answers part 2

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8.What are the types of data warehouses?
Ans - Following are the different types of data warehouses

• Data Mart 
• ODS (operational data store)  
• Enterprise Data Warehouse

9.What are the different types of metadata that stores in repository?
Ans - The different types of metadata that stores in repository are Source definition, Target definition, Mappings,Transformations and Mapplet.

10.What are an Expression transformation?
Ans- Expression transformation is a Passive and Connected transformation. It can be used to calculate values in a single row before writing to the target.

11.What are the differences between OLTP and OLAP?

Ans - Following are the differences    
    OLTP focuses on day to day transaction. OLTP gives Data Stability, it is dynamic and highly normalized.

    OLAP is static until it is refreshed, it is demoralized. OLAP focuses on future predictions and decisions

12.What is aggregated cache?
Ans - Aggregate cache is a temporary memory location that stores the input data values when the aggregation calculation is being carried out.

13.Why do we need to reinitialize aggregate cache?
Ans - It is needed to remove the previous data present in the aggregate cache and so that it can be used by the new source.

14.What is Dimension Table?
 Ans - It contains data used to reference data stored in the fact table. Has Fewer rows,Primarily character data,One primary key and Updatable data.

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