ask_kaushik

 Profile Answers by ask_kaushik Questions by ask_kaushik

• Dec 6th, 2007

 

The Union transformation is a multiple input group transformation that you use to merge data from multiple pipelines or pipeline branches into one pipeline branch. It merges data from multiple sources similar to the UNION ALL SQL statement to combine the results from two or more SQL statements. Similar to the UNION ALL statement, the Union transformation does not remove duplicate rows.
The Integration Service processes all input groups in parallel. The Integration Service concurrently reads sources connected to the Union transformation, and pushes blocks of data into the input groups of the transformation. The Union transformation processes the blocks of data based on the order it receives the blocks from the Integration Service.
You can connect heterogeneous sources to a Union transformation. The Union transformation merges sources with matching ports and outputs the data from one output group with the same ports as the input groups.

ask_kaushik

 Profile Answers by ask_kaushik Questions by ask_kaushik

• Dec 6th, 2007

 

That was the description....
practical use would be like : if you have 3 different sources which returns different number of records but with the same ports and datatypes, union transformation can be used to sum up these records and proceed to the next transformation as the same pipeline.