You need to create an interim table in the desired format to use the dbms_redefinition package. Following are the three procedures to create an interim table:
i. Start_redef_tab/e— Initiates redefinition process
ii. Sync_interim_table — Keeps the interim table synchronized with the orginal table. This procedure is useful in minimizing the amount of synchronization needed to be done by the finish_redef_table procedure before completing the online redefinition. The Sync_interim_table procedure can be called between long running operations (such as create index) on the interim table to synchronize it with the data in the original table and speed up the subsequent operations.
iii. Finish_redef_table — Completes redefinition process. It switches the names of original table and interim table.
Prerequisite for using the dbms_redefinition package is to have sufficient free space for interim table in an appropriate tablespace to be able to switch the table names.