I'm testing Core Data and iCloud with UIManagedDocument and ubiquity options (NSPersistentStoreUbiquitousContentNameKey and NSPersistentStoreUbiquitousContentURLKey). Everything is working OK. My devices get synched without problems and in an reasonable time. The DB is small (below 100K).
As i said I'm testing the app and making a lot of changes to the db and as result, a lot of transaction logs are generated. The problem I have is that if I delete and reinstall the app on one of the devices used for testing (without deleting iCloud data) the app take a very long time to open the document. openWithCompletionHandler takes minutes, sometimes never ends. If I turn on debugging (-com.apple.coredata.ubiquity.logLevel 3) i can see that there is a long wait and after that the DB is reconstructed with transaction logs. If i remove iCloud data and reinsert the data on first device the second one sync without problems. Because of that I think that the reason for the delay is a high number of transaction logs (20-30 while testing as I can see on developer.icloud.com) According to Managing Core Data iCloud Transaction Logs will handle core data automatically, but I can't see any deletion. Perhaps that needs some more time.
My questions are: Do transaction logs gets consolidated ever ? Can I force the consolidation of logs ? Another recommended option ?
I only store the subset of essential information needed for syncing in iCloud Core Data file. I have another local file with full DB, so I can reconstruct the iCloud DB without any major loss of information. Perhaps I could delete iCloud DB when I detect a bunch of logs and re-create it. Do you think this is a good option ?
Thank you for helping.
Do transaction logs gets consolidated ever ?
That is how it's supposed to work.
Can I force the consolidation of logs ?
No. There is no API that directly affects the existence of transaction logs. The iCloud system will consolidate them at some point, but there's no documentation regarding when that happens, and you can't force it.
Another recommended option ?
You can limit the number of transaction logs indirectly-- save changes less frequently. A transaction log corresponds to saving changes in Core Data. It may not make much of a difference because, honestly, 20-30 transaction logs is not very many. You might be able to reduce the number of log files but you'll still have the same amount of data in them.
Transaction logs aren't really your problem. As you observed, there's a long wait before iCloud starts running through the transaction logs. During that delay, iCloud is communicating with Apple's servers and downloading the transaction logs. Some of this is affected by network speed and latency, and the rest is just the way iCloud is.