1. A computing system comprising one or more computer-readable media having computer-executable instructions that, when executed by the computing system, implement a method for modifying a schema for a database, wherein the method comprises: setting a deactivation flag attribute of a first schema object of the schema to indicate that the first schema object is deactivated, the first schema object having a primary identifier, an internal identifier, and a first attribute; and creating a second schema object of the schema to supersede the first schema object, the second schema object having a primary identifier that is the same as the primary identifier, an internal identifier that is different from the internal identifier of the first schema object, a deactivation flag attribute that is set to indicate that the second schema object is active, and a second attribute corresponding to the first attribute but defined differently from the first attribute.