Introduction to Large Objects and SecureFiles

1 Introduction to Large Objects and SecureFiles

Large Objects are used to hold large amounts of data inside Oracle Database, SecureFiles provides performance comparable to file system performance, and DBFS provides file system interface to files stored in Oracle Database.

1.1 Migrating LOBs with Data Pump

Oracle Data Pump can either recreate tables as they are in your source database, or recreate LOB columns as SecureFile LOBs.

When Oracle Data Pump recreates tables, by default, it recreates them as they existed in the source database. Therefore, if a LOB column was a BasicFiles LOB in the source database, Oracle Data Pump attempts to recreate it as a BasicFile LOB in the imported database. However, you can force creation of LOBs as SecureFile LOBs in the recreated tables by using a TRANSFORM parameter for the command line, or by using a LOB_STORAGE parameter for the DBMS_DATAPUMP and DBMS_METADATA packages.

Example:

impdp system/manager directory=dpump_dir schemas=lobuser dumpfile=lobuser.dmp
      transform=lob_storage:securefile

Note:

The transform name is not valid in transportable import.

See Also:

TRANSFORM for using TRANSFORM parameter to convert to SecureFile LOBs

Restrictions on Migrating LOBs with Data Pump

You can't use SecureFile LOBs in non-ASSM tablespace. If the source database contains LOB columns in a tablespace that does not support ASSM, then you'll see an error message when you use Oracle Data Dump to recreate the tables using the securefile clause for LOB columns.

To import non-ASSM tables with LOB columns, run another import for these tables without using TRANSFORM=LOB_STORAGE:SECUREFILE.

Example:

impdp system/manager directory=dpump_dir schemas=lobuser dumpfile=lobuser.dmp