1. A computer-implemented method for performing a persistent data upgrade, comprising: instantiating, by a computer, a shadow system for a new version software application and a shadow system database schema in a database shared with a production system executing a first version software application, the shadow system database schema acting as a database connector and containing aliases pointing to tables instantiated in a production database schema associated with the production system; instantiating a bridge database schema in the database, wherein the bridge database schema contains aliases pointing to each database table within the production database schema; preparing a bridge sub-system to execute as a first version software application, the bridge sub-system connected to the aliases contained within the bridge database schema; replicating database tables within the production database schema, wherein the replicated database tables are used by the bridge sub-system and the original database tables are adjusted for structure and content consistent with the new version software application; deploying an upgrade sub-system and tools to complete adjustment of structure and content of the original database tables, thereby created new version database tables, for the new version software application; and instantiating an instance of the new version software application and connecting the new version software application to the new version database tables.