Deleting the app and reinstalling it

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SQL-Server

Mobile

Android

, +

I'm developing an application that has favorite contacts, in my database i have 2 tables one for the favorites and one the not favorite contacts, and every favorite contact has a specific image id that have been selected by the user...

my problem is that if the user deletes the app and reinstall it, I'm getting all his contact list from the beginning and deleting all his favorites and return for him the new data... but i need keep the specific image for the favorites... and when I'm deleting everything I'm losing this field.. and if i don't delete everything and reinsert from beginning then i have to check for every contact if he exists as favorite and my table is extremely huge so this method is very slow and have a bad performance so deleting and reinserting is much faster...

so does anyone have any idea that does not effect the performance of the app and tell how to keep the old data of the user when deleting the app and reinstalling it?

thank you for your support...