I created a Data Module first time today and uploaded an Excel file with only two columns. Joined the 1st column of the Excel file to a Data Item from a package. Made a report and ran it to fetch data only foe one day (chose today's date from the Date parameter). Report keeps running for 5 minutes!!
Same report was running earlier in 2 seconds when it was using only the package. Yes, that second column from the Excel file was a Data Item in the package itself. That second column was derived using a Case statement based on the value of the first column.
Is this supposed to be the behavior of Data Modules? Is it because the Excel file gets loaded into the Content Store database and then the Data Warehouse table used by the package gets joined to the table in Content Store database? Those are different databases.