data waqrehousing interview qa-6
50. How do automate/schedule sessions/batches n did u use any tool for automating Sessions/batch?
Ans: We scheduled our sessions/batches using Server Manager.
You can either schedule a session to run at a given time or interval, or you can manually start the session.
U needto hv create sessions n batches with Read n Execute permissions or super user privilege.
If you configure a batch to run only on demand, you cannot schedule it.
Note: We did not use any tool for automation process.
51. What are the differences between 4.7 and 5.1 versions?
Ans: New Transformations added like XML Transformation and MQ Series Transformation, and PowerMart and PowerCenter both
are same from 5.1version.
52. What r the procedure that u need to undergo before moving Mappings/sessions from Testing/Development to Production?
Ans:
53. How many values it (informatica server) returns when it passes thru Connected Lookup n Unconncted Lookup?
Ans: Connected Lookup can return multiple values where as Unconnected Lookup will return only one values that is Return Value.
54. What is the difference between PowerMart and PowerCenter in 4.7.2?
Ans: If You Are Using PowerCenter
PowerCenter allows you to register and run multiple Informatica Servers against the same repository. Because you can run
these servers at the same time, you can distribute the repository session load across available servers to improve overall
performance.
With PowerCenter, you receive all product functionality, including distributed metadata, the ability to organize repositories into
a data mart domain and share metadata across repositories.
A PowerCenter license lets you create a single repository that you can configure as a global repository, the core component
of a data warehouse.
If You Are Using PowerMart
This version of PowerMart includes all features except distributed metadata and multiple registered servers. Also, the various
options available with PowerCenter (such as PowerCenter Integration Server for BW, PowerConnect for IBM DB2,
PowerConnect for SAP R/3, and PowerConnect for PeopleSoft) are not available with PowerMart.
55. What kind of modifications u can do/perform with each Transformation?
Ans: Using transformations, you can modify data in the following ways:
----------------- ------------------------
Task Transformation
----------------- ------------------------
Calculate a value Expression
Perform an aggregate calculations Aggregator
Modify text Expression
Filter records Filter, Source Qualifier
Order records queried by the Informatica Server Source Qualifier
Call a stored procedure Stored Procedure
Call a procedure in a shared library or in the External Procedure
COM layer of Windows NT
Generate primary keys Sequence Generator
Limit records to a top or bottom range Rank
Normalize records, including those read Normalizer
from COBOL sources
Look up values Lookup
Determine whether to insert, delete, update, Update Strategy
or reject records
Join records from different databases Joiner
or flat file systems
56. Expressions in Transformations, Explain briefly how do u use?
Ans: Expressions in Transformations
To transform data passing through a transformation, you can write an expression. The most obvious examples of these are the
Expression and Aggregator transformations, which perform calculations on either single values or an entire range of values
within a port. Transformations that use expressions include the following:
--------------------- ------------------------------------------
Transformation How It Uses Expressions
--------------------- ------------------------------------------
Expression Calculates the result of an expression for each row passing through the transformation, using values from one or more ports.
Aggregator Calculates the result of an aggregate expression, such as a sum or average, based on all data passing through a port or on groups within that data.
Filter Filters records based on a condition you enter using an expression.
Rank Filters the top or bottom range of records, based on a condition you enter using an expression.
Update Strategy Assigns a numeric code to each record based on an expression, indicating whether the Informatica Server should use the information in the record to insert, delete, or update the target.
In each transformation, you use the Expression Editor to enter the expression. The Expression Editor supports the transformation language for building expressions. The transformation language uses SQL-like functions, operators, and other components to build the expression. For example, as in SQL, the transformation language includes the functions COUNT and SUM. However, the PowerMart/PowerCenter transformation language includes additional functions not found in SQL.
When you enter the expression, you can use values available through ports. For example, if the transformation has two input ports representing a price and sales tax rate, you can calculate the final sales tax using these two values. The ports used in the expression can appear in the same transformation, or you can use output ports in other transformations.
57. In case of Flat files (which comes thru FTP as source) has not arrived then what happens?Where do u set this option?
Ans: U get an fatel error which cause server to fail/stop the session.
U can set Event-Based Scheduling Option in Session Properties under General tab-->Advanced options..
----------------- ------------------- ------------------
Event-Based Required/ Optional Description
----------------- -------------------- ------------------
Indicator File to Wait For Optional Required to use event-based scheduling. Enter the indicator file
(or directory and file) whose arrival schedules the session. If you do
not enter a directory, the Informatica Server assumes the file appears
in the server variable directory $PMRootDir.
58. What is the Test Load Option and when you use in Server Manager?
Ans: When testing sessions in development, you may not need to process the entire source. If this is true, use the Test Load
Option(Session Properties à General Tab à Target Options èChoose Target Load options as Normal (option button), with
Test Load cheked (Check box) and No.of rows to test ex.2000 (Text box with Scrolls)). You can also click the Start button.
59. What is difference between data scrubbing and data cleansing?
Ans: Scrubbing data is the process of cleaning up the junk in legacy data and making it accurate and useful for the next generations
of automated systems. This is perhaps the most difficult of all conversion activities. Very often, this is made more difficult when
the customer wants to make good data out of bad data. This is the dog work. It is also the most important and can not be done
without the active participation of the user.
DATA CLEANING - a two step process including DETECTION and then CORRECTION of errors in a data set
60. What is Metadata and Repository?
Ans:
Metadata. “Data about data” .
It contains descriptive data for end users.
Contains data that controls the ETL processing.
Contains data about the current state of the data warehouse.
ETL updates metadata, to provide the most current state.
Repository. The place where you store the metadata is called a repository. The more sophisticated your repository, the more
complex and detailed metadata you can store in it. PowerMart and PowerCenter use a relational database as the
repository.
Ans: We scheduled our sessions/batches using Server Manager.
You can either schedule a session to run at a given time or interval, or you can manually start the session.
U needto hv create sessions n batches with Read n Execute permissions or super user privilege.
If you configure a batch to run only on demand, you cannot schedule it.
Note: We did not use any tool for automation process.
51. What are the differences between 4.7 and 5.1 versions?
Ans: New Transformations added like XML Transformation and MQ Series Transformation, and PowerMart and PowerCenter both
are same from 5.1version.
52. What r the procedure that u need to undergo before moving Mappings/sessions from Testing/Development to Production?
Ans:
53. How many values it (informatica server) returns when it passes thru Connected Lookup n Unconncted Lookup?
Ans: Connected Lookup can return multiple values where as Unconnected Lookup will return only one values that is Return Value.
54. What is the difference between PowerMart and PowerCenter in 4.7.2?
Ans: If You Are Using PowerCenter
PowerCenter allows you to register and run multiple Informatica Servers against the same repository. Because you can run
these servers at the same time, you can distribute the repository session load across available servers to improve overall
performance.
With PowerCenter, you receive all product functionality, including distributed metadata, the ability to organize repositories into
a data mart domain and share metadata across repositories.
A PowerCenter license lets you create a single repository that you can configure as a global repository, the core component
of a data warehouse.
If You Are Using PowerMart
This version of PowerMart includes all features except distributed metadata and multiple registered servers. Also, the various
options available with PowerCenter (such as PowerCenter Integration Server for BW, PowerConnect for IBM DB2,
PowerConnect for SAP R/3, and PowerConnect for PeopleSoft) are not available with PowerMart.
55. What kind of modifications u can do/perform with each Transformation?
Ans: Using transformations, you can modify data in the following ways:
----------------- ------------------------
Task Transformation
----------------- ------------------------
Calculate a value Expression
Perform an aggregate calculations Aggregator
Modify text Expression
Filter records Filter, Source Qualifier
Order records queried by the Informatica Server Source Qualifier
Call a stored procedure Stored Procedure
Call a procedure in a shared library or in the External Procedure
COM layer of Windows NT
Generate primary keys Sequence Generator
Limit records to a top or bottom range Rank
Normalize records, including those read Normalizer
from COBOL sources
Look up values Lookup
Determine whether to insert, delete, update, Update Strategy
or reject records
Join records from different databases Joiner
or flat file systems
56. Expressions in Transformations, Explain briefly how do u use?
Ans: Expressions in Transformations
To transform data passing through a transformation, you can write an expression. The most obvious examples of these are the
Expression and Aggregator transformations, which perform calculations on either single values or an entire range of values
within a port. Transformations that use expressions include the following:
--------------------- ------------------------------------------
Transformation How It Uses Expressions
--------------------- ------------------------------------------
Expression Calculates the result of an expression for each row passing through the transformation, using values from one or more ports.
Aggregator Calculates the result of an aggregate expression, such as a sum or average, based on all data passing through a port or on groups within that data.
Filter Filters records based on a condition you enter using an expression.
Rank Filters the top or bottom range of records, based on a condition you enter using an expression.
Update Strategy Assigns a numeric code to each record based on an expression, indicating whether the Informatica Server should use the information in the record to insert, delete, or update the target.
In each transformation, you use the Expression Editor to enter the expression. The Expression Editor supports the transformation language for building expressions. The transformation language uses SQL-like functions, operators, and other components to build the expression. For example, as in SQL, the transformation language includes the functions COUNT and SUM. However, the PowerMart/PowerCenter transformation language includes additional functions not found in SQL.
When you enter the expression, you can use values available through ports. For example, if the transformation has two input ports representing a price and sales tax rate, you can calculate the final sales tax using these two values. The ports used in the expression can appear in the same transformation, or you can use output ports in other transformations.
57. In case of Flat files (which comes thru FTP as source) has not arrived then what happens?Where do u set this option?
Ans: U get an fatel error which cause server to fail/stop the session.
U can set Event-Based Scheduling Option in Session Properties under General tab-->Advanced options..
----------------- ------------------- ------------------
Event-Based Required/ Optional Description
----------------- -------------------- ------------------
Indicator File to Wait For Optional Required to use event-based scheduling. Enter the indicator file
(or directory and file) whose arrival schedules the session. If you do
not enter a directory, the Informatica Server assumes the file appears
in the server variable directory $PMRootDir.
58. What is the Test Load Option and when you use in Server Manager?
Ans: When testing sessions in development, you may not need to process the entire source. If this is true, use the Test Load
Option(Session Properties à General Tab à Target Options èChoose Target Load options as Normal (option button), with
Test Load cheked (Check box) and No.of rows to test ex.2000 (Text box with Scrolls)). You can also click the Start button.
59. What is difference between data scrubbing and data cleansing?
Ans: Scrubbing data is the process of cleaning up the junk in legacy data and making it accurate and useful for the next generations
of automated systems. This is perhaps the most difficult of all conversion activities. Very often, this is made more difficult when
the customer wants to make good data out of bad data. This is the dog work. It is also the most important and can not be done
without the active participation of the user.
DATA CLEANING - a two step process including DETECTION and then CORRECTION of errors in a data set
60. What is Metadata and Repository?
Ans:
Metadata. “Data about data” .
It contains descriptive data for end users.
Contains data that controls the ETL processing.
Contains data about the current state of the data warehouse.
ETL updates metadata, to provide the most current state.
Repository. The place where you store the metadata is called a repository. The more sophisticated your repository, the more
complex and detailed metadata you can store in it. PowerMart and PowerCenter use a relational database as the
repository.
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