Why Union transformation is active transformation in Informatica?

Why Union transformation is active transformation in Informatica?

Transformation are judged as Active or Passive on basis of rownum changes, means like after records passes thru the transformation does rownum changes. If yes then it’s Active or else passive.

To consolidate up, here are the reasons:

1.   It is built over a transformation called External procedure transformations which are active.

2.   By default in the Union transformation properties the active property is enabled and cannot be edited.

3.   Whenever it merges the data, it changes the rownum of each row/ record.

Let me show this with you below example:

Table A

Rownum	ID	Name
1	10	aaa
2	20	bbb
3	30	ccc

Table B

Rownum	ID	Name
5	50	aaaa
6	60	bbbb
7	70	cccc

Now when you pass these two tables’ records to union transformation the output will be like 

ID	Name	New Rownum	Old Rownum
10	aaa	1	1
50	aaaa	2	5
20	bbb	3	2
60	bbbb	4	6
30	ccc	5	3
70	cccc	6	7

Compare new rownum with old rownum you will find the difference. That’s how union transformation is active although it doesn't changes number of records passing through it.