1. A method for maintaining a consistent state during data migration in a database system comprising: storing an image of data in a database table of an active database system into a snapshot table at a specified point in time; copying the data into a corresponding database table of a shadow database system during a time interval when active data operations are being performed on the data in the active database system; after the data has been copied into the database table of the shadow database system, comparing the data stored in the database table of the shadow database system with the corresponding data stored in the snapshot table; restoring a consistent state when the data in the database table of the shadow database system does not match the corresponding data in the snapshot table, wherein restoring comprises copying data stored in the snapshot table into the database table of the shadow database system; and completing data migration when the data stored in the database table of the shadow database system matches the data stored in the snapshot table.