In accordance with embodiments, there are provided mechanisms and methods for performing transparent object migration across storage tiers. In an embodiment and by way of example, a method for appending data to large data volumes is provided. The method embodiment includes a) setting a CustomEntityOption bit that determines (at object creation time) where the object is stored, either in the relational or the non-relational data store portion, b) loading the CustomEntityOption bit in a cached CustomEntityDefinition, c) showing the CustomEntityOption bit as EntityInfo, and d) allowing custom object definition and Metadata API functionality when the bit is shown.