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What is the difference between mapping parameter & mapping variable in data warehousing?
What are the types of variable available in data warehousing?

Total Answers and Comments: 4

Last Update: April 22, 2009 Asked by: vikram

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Submitted by: VVM.SP

Mapping Parameter: Define the constant value, it can't change the value throught the session.

Mapping Variables: Define the value, It can be change througout the session

Above answer was rated as good by the following members:
dhiveya.m

November 17, 2007 06:49:52

Thananjayan

Member Since: November 2007 Contribution: 15

RE: What is the difference between mapping parameter &...

Hi

Mapping parameter is a dynamic normally pass the value to this parameter through the prarameter file(.par file).we can pass the parameter dynamically at every time the session runs.This can be set to the relevent variable called by using the $$ sign.

Mapping variable is static.we can't change the value of this variable during runtime.

Cheers
Thana

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March 18, 2008 02:57:53

VVM.SP

Member Since: March 2008 Contribution: 7

RE: What is the difference between mapping parameter & mapping variable in data warehousing?What are the types of variable available in data warehousing?

Mapping Parameter: Define the constant value it can't change the value throught the session.

Mapping Variables: Define the value It can be change througout the session

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Overall Rating: +1

July 18, 2008 11:12:20

fir_dan

Member Since: July 2008 Contribution: 2

RE: What is the difference between mapping parameter & mapping variable in data warehousing?What are the types of variable available in data warehousing?

A mapping parameter is a static value that you define before running the session and it retains the same value till the end of the session. Define a parameter in paramaeter file (.par) and use it in mapping or maplet and when PowerCenter server the runs the session it evaluates the value from the parameter and retains the same value throughout the session. When the session run again it reads from the file for its value.

A mapping variable is dynamic or changes anytime during the session. PowerCenter reads the intial value of the variable before the start of the session and changes its value by using variable functions and before ending the session its saves the current value (last value held by the variable). Next time when the session runs the variable value is the last saved value in the previous session. For example if you have a count variable that it gets incremented every time a session is run the variable will have a value of 3 on its 4th run. The variable value will not be saved by the session when it fails or when it is configured for a test load or when it runs on a debug mode. There is also another option not save the variable value at the end of the session by discarding session output so it that everytime it starts it will take the intial value not the last saved value.

Thanks
Dani.

A variable type is defined based on its aggregation viz count min and max. Informatica give three functions for the three variable functions for each of this type SetCountVariable SetMaxVariable SetMinVariable. It also limits the datatypes used within these types like the count type can have only integer and small integer datatypes where as min and max can use any datatype. A variable cannot use a binary datatype.

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April 22, 2009 03:02:28

dhiveya.m

Member Since: April 2009 Contribution: 1

RE: What is the difference between mapping parameter & mapping variable in data warehousing?What are the types of variable available in data warehousing?

Mapping parameter are the constant values (values never changes) and mapping variables are the values that ever changes.

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