Flashback Table

If a DDL operation has altered the structure of any tables in the database, flashback operations cannot be used to undo those operations. DDL operations that cannot be flashed back include  upgrading, moving or truncating a table, adding a table to a cluster, dropping or altering a column; and adding, dropping, splitting, coalescing or truncating a partition or sub-partition. DLL operations that change the storage attributes for the table are not impacted by the FLASHBACK TABLE command.

If a transaction is processing, it will be necessary to COMMIT or ROLLBACK the operation before using the FLASHBACK TABLE command.

Flashback Drop

In previous releases of Oracle database, dropping the tables was an irrecoverable operation without restoring from media. This was time consuming and often resulted in loss of work and database changes made during this period.

In Oracle Database 10g, when a table is dropped, it is placed in a recycle bin. The extents allocated to the table are not deallocated until they are purged. The tablespace counts the space used by these objects against its quota until they are purged. Constraints and triggers are preserved even after moving an object to the recycle bin.

For implicit database operations like DROP TABLESPACE INCLUDING CONTENTS or DROP USER CASCADE .., objects are not placed in the recycle bin. All objects belonging to the dropped tablespace or user in the recycle bin are purged.