1. A computer-implemented method of in-place metadata transformation for a system software upgrade from an original software version to an upgraded software version in a massively parallel shared data store system, comprising: cloning original system metadata to provide a copy of cloned metadata within the system; transforming the copy of cloned metadata in place within the system using the original software version to produce transformed metadata by applying software upgrade related changes to the copy of cloned metadata as required by the upgraded software version; updating using the original software version system dependencies that are changed by said transformed metadata; building a shadow system comprising the transformed metadata and related system dependencies changed by said transformed metadata; atomically swapping the transformed metadata and the original system metadata to provide an upgraded system; and validating the upgraded system by running the upgraded system using the upgraded software version.