Union Transformation

Why Union transformation is active while it returns same number of rows as in the sources?

Questions by saurabh7385

Showing Answers 1 - 21 of 21 Answers

suvomoy.chakraborty@patni.com

  • Apr 4th, 2008
 

Union Transformation in general does not allow duplicate rows. If the sources contain duplicate rows then the effective count of rows after union certainly will be reduced. That should be one of the reasons for it being an active transformation.

A question may be raised regarding a situation where the sources do not contain any duplicates. The answer should be even in that scenario the transformation's inherent ability to check for the duplicate rows will remain intact. Just like a filter transformation not changing the row count because the filter condition was not either entirely true or entirely false for all of the rows.

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nandu214

  • Jun 22nd, 2008
 

But union transformation doesn't delete the duplicate records when we are joining two tables i found this information in Informatica help.

can  anyone throw light on this.

Rashmirekha

  • Jul 9th, 2008
 

Hi,

Please make a note that there is no option available in a Union transformation to handle duplicates.It does a 'UNION ALL'. If handling of duplicates is the requirement then Sorter can be used.

gaurav2485

  • Jan 8th, 2009
 

Suppose we have 2 Source with 100 & 200 rows then output will be 300 rows so I/p O/p rows number vhange that is Active transformation 

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chvamshy

  • Feb 27th, 2009
 

Union Transformation is active, because you configure a session using update strategy the session property data driven instructs informatica server to use the instructions coded in mapping to flag the rows for insert, update, delete, this is the default option selected when using a update strategy transformation in a mapping.

Union transformation is developed using the Multigroup External Procedure transformation which is an active transformation.

Regards,
Vamshi Cheedella

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harikr

  • Dec 1st, 2009
 

An active transformation can change the number of rows that pass through it. A passive transformation does not change the number of rows that pass through it.

Union Transformation does UNION ALL; hence it changes the number of rows as Duplicates are not removed. Hence, UNION transformation is considered ACTIVE.

prashant.baranwal

  • Sep 18th, 2010
 

Union transformation is an active transformation and it does changes the number of records.

Suppose source has following columns:
Name, School, College
ABC, SKM, IIT-D
XYZ, DAV, IIM

There are total 10 rows coming from source with all attributes populated. Now we create two groups in union with group ports Name and Institute. Connect first group with Name and School and second group with Name and COllege. It will generate a total of 20 records in the target.

Result would be like:
ABC, SKM
ABC, IIT-D
XYZ, DAV
XYZ, IIM

Hope it clears, why UNION is an active transformation.

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