mysql - Online storage / sync of large iPhone user databases: perform on server or on device? -


i'm working on online user database backup / sync system popular sqlite-based iphone flashcard app; large-scale - pretty 100 million individual flashcard records or more (10,000 users, 10,000 cards each) - , need design system sort of scalability in mind. we're not in web-based software business, , @ least we're not planning give of web interface except account administration - of actual manipulation of user data occur offline.

so seems have 2 basic options how implement this:

  • perform sync on server; store users' data in mysql database (or bunch of them scale up) , download / upload lists of changes only.

  • perform sync locally; download latest version of database server, check / apply changes on-device, upload merged database.

it seems local sync option mean lot less programming work , lower hosting costs on our end, mean more bandwidth usage our users - on order of 2-4 mb each sync operation versus few dozen k web-based sync.

does feel 1 of these options better other? there other way of doing haven't considered?

thanks.

i way off way works but, synchronisation, why local copy of database not able record list of changes can replicated on server side? works single device of course not syncing multiple devices same data set.

the changes noted in various ways: eg checksum records on iphone , checksum them again when synchronising, upload ones have changed, deletions need recorded seperately.


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