Table truncated, but segments were not cleaned

Question

Hi,
I am running oracle 11g 11.2.0.1.0 version on ASM.
I have truncated a 3.5 GB partitioned table, but the extents are not getting dropped and space is not getting released.
the table do not have any rows now, but the dba_extents and dba_segments are still showing 3.5 gb size.
Please suggest what could be the possible reason.
Please let me know if additional information is required to answer my qustion.
regards

Answer 1

Here's a demo which shows that if a table is created with a large INITIAL, a TRUNCATE doesn't shrink the initial size.  A MOVE with a STORAGE clause can.
SQL> create table hkc_test_99 (id_column number, data_column varchar2(10)) storage (initial 64M);
Table created.
SQL> insert into hkc_test_99 select 1,'One' from dual;
1 row created.
SQL> commit;
Commit complete.
SQL> select extent_id, bytes/1024 from user_Extents where segment_name = 'HKC_TEST_99';
EXTENT_ID BYTES/1024
         0      65536
1 row selected.
SQL>
SQL> truncate table hkc_test_99;
Table truncated.
SQL> select extent_id, bytes/1024 from user_Extents where segment_name = 'HKC_TEST_99';
EXTENT_ID BYTES/1024
         0      65536
1 row selected.
SQL>
SQL> alter table hkc_test_99 move storage (initial 64K);
Table altered.
SQL> select extent_id, bytes/1024 from user_Extents where segment_name = 'HKC_TEST_99';
EXTENT_ID BYTES/1024
         0         64
1 row selected.
SQL>
Hemant K Chitale