When to use Change data source activity
I'm trying to explore this new activity in V8 and while doing testing, I observed that the workflow is running without using Change data source activity. Below is the scenario that I was testing:
Created one schema in local and one in Cloud. Queried both schemas and intersected on email address field, which is the common field for both, keeping the primary set as cloud schema. The workflow ran successfully.

But when I kept the primary set as local schema, it kept failing due to:
01/25/2022 3:07:08 AM union PGS-220000 PostgreSQL error: ERROR: COALESCE types integer and character varying cannot be matched LINE 1: ...yaltyBalance) SELECT DISTINCT Coalesce(Input1.iId,Input2.uId... ^ .
When do we actually need to use Change Data source activity?
