Hello Mahesh,
I believe this decision will come after a little homework. After all, there are too many unknown factors at this point that need to be considered. In fact, it depends on the type of hardware your source database is installed on, the type of RDBMS you are using, the amount of rows that are to be loaded, the amount of memory available to QlikView, the period of the day the load takes place, etc.
For small tables, I don't foresee any difference in performance, but for very large tables, it might. Also, depending on the type of join, in one case it can be very heavy for a database to manage, while in QlikView, with a few ApplyMap() to replace codes with descriptions, for example, it does not affect the load process very much.
To be known, in RDBMS's such as Oracle, the engine can precompile statements and keep them in cache if they are used quite often. So for complex joins, maybe you can create a view in the source system?
In brief, while there aren't any pre-defined answers for your question, there might be a lot of possible solutions, all depending on your current implementation.
Hope this helps, regards,
Philippe
