Thanks Vijeta.
I figured out entire database export from CDM database. Thats easy and admin part. Thats may not fit real business case.
I will give few examples-
1. user visit a credit card powerapp site and export last 6 months of his credit history(in powerapps UI in future)- we can not give a user entire credit card user database for export
2. user visit travel, airline booking powerapp and wants to export next 2 week's available flights(we can not give user entire flight booking database and point him to CDM database)
3. User goes to big shopping app(designed in powerapp) and wants to see/export his recent wishlist- we can not give user entire wishlist database that contains wishlist of all years/all users.
I hope above 3 points clarify business need of export to excel. In general now a days users want upto mark data with pin point accuracy and relevance(amazon.com shopping experience is best example).