释放delete空间

china_neo

The Oracle Database provides a Segment Advisor that helps you determine whether an object has space available for reclamation based on the level of space fragmentation within the object.    In general, the extents of a segment do not return to the tablespace until you drop the schema object whose data is stored in the segment (using a DROP TABLE or DROP CLUSTER statement). Exceptions to this include the following:

   
The owner of a table or cluster, or a user with the DELETE ANY privilege, can truncate the table or cluster with a TRUNCATE...DROP STORAGE statement.
   
   
A database administrator (DBA) can deallocate unused extents using the following SQL syntax: ALTER TABLE table_name DEALLOCATE UNUSED;
   
    Periodically, Oracle deallocates one or more extents of a rollback segment if it has the OPTIMAL size specified.



    When extents are freed, Oracle modifies the bitmap in the datafile (for locally managed tablespaces) or updates the data dictionary (for dictionary managed tablespaces) to reflect the regained extents as available space. Any data in the blocks
of freed extents becomes inaccessible.

gotoplay

谁说说用DEALLOCATE来回收这种空间和move有区别吗？