Question

I have a synchronization process and Im using Core Data to store a lot of information. Several times I downloaded the real SQLite database file with the organizer to check if the data is correct.

Some days ago I recongized that the size difference of two SQLite files was huge. One file was 80MB, the other file about 100MB. As I checked out the data in it with a SQLiteviewer there was no difference. The same tables, same indexes, same rows. How can that be? Is is is possible that some data is still in the file when I delete objects over Core Data?

EDIT:

The solution is an option flag which can be inserted in an option NSDictionary and added as parameter to the addPersistentStore method.

NSSQLiteManualVacuumOption
Option key to rebuild the store file, forcing a database wide defragmentation when the store is added to the coordinator.

This invokes SQLite's VACUUM command. It is ignored by stores other than the SQLite store.

Answer 1

Sqlite does not proactively return unused disk space as it deletes data, for performance reasons. This could be why you see the difference. See this link for more info:

SQLite FAQ