Hello Ranjit,
Hope you are doing good!
Does this means that you are comparing SQL server data with QVD and doing further processing?
Few inputs based on initial assessment:
1. If SQL Server table and QVD data has same structure then you can load the QVD and then append the SQL Server table data with it (Insert - Update Only).
2. If two tables have structural asymmetry and join is the preferable solution then go ahead and apply the join.
3. Scenario and Sample will be of help to provide you expected solution.
Regards!
Rahul