“Dropping component because of a prior component with the same name” warning in DataStage


Sometimes while working with the joins/lookups you may get the following warning in DataStage:

lkp_onEMP_NAME: When checking operator: On output data set 0: Dropping component “EMP_NAME” because of a prior component with the same name.

EMP_NAME field is given for information purpose and it can be any column other than key column from the input data and DataStage will give you a warning for each column exactly like above.


If you want to avoid the dropping component warning, please read the below instructions.

Anytime you have a join or a lookup the operator tries to take every field on both incoming links to the output link.

In the event that a field is named the same on both links, you get this warning and one gets dropped.

The only exception to that is the keys used for joins in which it automatically drops one of the fields because it knows they must have matched (i.e: identical) for the row to be in the output link.

The only solution here is to make sure that field EMP_NAME is renamed on one of the incoming links (ie: EMP_NAME_Table_Name or EMP_NAME_Lookup).

In the event that one of your “incoming” links is a reject from a previous stage, and you are unable to modify it, then you have two options.

    1. One is to put in a “no-op” modify stage on the link before it reaches the problem stage. The modify stage just keeps all the fields, but renames the “duplicate” ones.
  1. The other option is to rename the fields on the “other” incoming link. If this is a table being used for a lookup, remember you can use the “AS new-name” qualifier to rename an incoming field.

You don’t have duplicate names coming in on the two input links and still you are getting the warning, they are usually being propagated invisibly through the job because Runtime Column Propagation is turned on.



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