I am using SQL Server Compact Edition 3.5 on a mobile device. Synchronisation using the sync framework works fine in the context of the user doing it via a button press and waiting for it to complete. There are no issues there.
I have recently attempted to do this in a background thread which runs every ‘n’ minutes or so. This also works fine, provided I am not using the database at the time. If I am using the database, the whole app locks up and I haven’t yet found the specific exception that must be happening. I will continue to do that, but that is not part of my question.
My question is does the SqlCeClientSyncProvider somehow throw an exclusive lock or otherwise physically lock the .SDF file during synchronisation? If so, are there any options to override this behaviour?
No, it doesn’t lock the .SDF file, after testing I see that at most it creates a transaction with a read committed isolation level. The issue I was having was a deadlocking issue in my own threading code — which I was able to resolve after some careful refactoring. I was raising an event ‘SyncBegun’ before the sync happened and raising a subsequent event ‘SyncEnded’ afterwards. These were using separate locks which were stepping on each other’s toes.