You can see all the objects and allocated extents in that datafile by using this query.
Code:
SELECT SEGMENT_NAME, SEGMENT_TYPE, EXTENT_ID, BLOCK_ID
FROM DBA_EXTENTS 
WHERE FILE_ID = n;
BLOCK_ID is the starting block_id for the extent.

Sanjay


[Edited by SANJAY_G on 07-19-2002 at 05:44 AM]