Space is not released from tablespaces even after purging recycbin

Question

Hi,
I had 168GB of space occupied by recyclebin objects (BIN$...) when i queried on dba_segments, after purging the recyclebin it is showing 0.
But i didn't find any difference in the free space dba_free_space in tablespaces before and after purging.
Is it the thing that even after purging recycbin, it is not released the space for respective Tablespaces?
Also wanted to know how to release the space.
Thanks,
Mahi

Answer 1

If you have a table X, with segments in tablespace TS, and you drop the table, you now have a recycle bin object BIN$X that owns those same segments in that same tablespace TS. That's why the segments still appear in DBA_SEGMENTS. But Oracle knows that it is free to reuse the segments associated with BIN$X if it runs out of other space to use (and Oracle knows to reuse segments from recycle bin objects in the order they were dropped) so the segments are free in DBA_FREE_SPACE. Just like deleting a file on the file system is just updating a pointer to some sort of file allocation table but not actually removing the bits from the hard drive, dropping an object when the recycle bin is just marking the segments as no longer associated with a real object.
I have no idea whether 11g has changes to recover index names-- you might take a look at the 11g documentation (either the New Features guide or the Flashback Drop docs).
Justin