Techniques and solutions are described for facilitating the conversion of tables, having primary data and an append specifying a format of append data, from a first format to a second format. A runtime object and a data dictionary entry can be created for a primary table in the second format, and at least a portion of primary data transferred to the primary table in the second format. A database layer object corresponding to the first table in the first format can be associated with a temporary runtime object and a temporary data dictionary entry so that append data can be transferred to an append table in the second format. Operations directed to the primary table in the second format can be modified to also be directed to the append table, such as using a JOIN view.