Migrating from LONGs to LOBs

During migration from LONGs to LOBs, the redo changes for the table are logged only if the table has LOGGING on. Redo changes for the column being converted from LONG to LOB are logged only if the storage characteristics of the LOB indicate LOGGING. The default value for LOGGING|NOLOGGING for the LOB is inherited from the tablespace in which the LOB is being created.

Preventing Generation of Redo Space During Migration

To prevent generation of redo space during migration and migrate smoothly, use the following statements:

1. ALTER TABLE Long_tab NOLOGGING;

2. ALTER TABLE Long_tab MODIFY ( long_col CLOB [default <default_val>]) LOB (long_col) STORE AS (... NOLOGGING ...);

3. ALTER TABLE Long_tab MODIFY LOB long_col STORE AS (...LOGGING...);

4. ALTER TABLE Long_tab LOGGING;

5. Take a backup of the tablespaces containing the table and the LOB.

   See Also: Chapter 8, "Migrating From LONGs to LOBs"