I am new to Denodo, just have installed Denodo Express Server.I am running a sample task.
I have two disparate data sources (Postgres and MySQL), Postgres has agents table while MySQL has Customer and Orders data. When I execute a join statement between agents and Customer data it return 0 rows, until I cache Customer data.
I have attached the Execution Trace of the query, both Virtual Plans return some rows but Inner Join Plan results 0 rows.
I guess you are joining TEXT field. May be in your text field there is space before and after field or In-between tow word.
You can use trim()
for both side before joining OR Try to remove all space from your string and Join.
I am just Guessing because you didn't provide join condition.