US Patent 9244914 Schema versioning for cloud hosted databases

Methods and apparatus are provided in which applications that run on different devices can be upgraded with migration of data to a new database format. A method of upgrading a first version of an application installed on a first device to a second version is provided, where first and second transaction logs for respective first and second schema versions are stored in respective first and second log containers on a server computer, and the first version of the application stores data in accordance with a first schema version, and further stores a cache of at least a portion of the first transaction log in a log database on the first device, migrating the log database to the second schema version, storing a duplicate copy of the first transaction log in the second log container, and rewriting the duplicate copy of the first transaction logs using the second schema.