Table fragmentation

Question

Hi all
Please can one explain me which process is correct and less error free and less complecation to do a defragmentation
1) take export of table and drop it and import it
2) move table within the tablespcae
3) take backup of table by select * from to backup table and truncate the main table and again insert the records from backup table to main table
which is best and standerd approch
Thanks

Answer 1

Hi Arun,
i recomend option 4, shrink:
1) enable row movement
ALTER TABLE scott.test ENABLE ROW MOVEMENT;
2) move object rows and indexes (no lock)
ALTER TABLE scott.test SHRINK SPACE CASCADE COMPACT;
3) reset HMW (lock table!!!)
ALTER TABLE scott.test SHRINK SPACE CASCADE;
4)disable row movement
ALTER TABLE scott.test DISABLE ROW MOVEMENT;
with this you give free space to the tablespace.
You can check reserved space, as you said "fragmentation":
select table_name, NUM_ROWS,(blocks*8/1024)+ROUND((AVG_ROW_LEN * NUM_ROWS / (1024 * 1024)), 2) TOTAL, blocks*8/1024 Reserved_MB,  ROUND((AVG_ROW_LEN * NUM_ROWS / (1024 * 1024)), 2) Consumed_MB,
((blocks*8/1024)*100)/((blocks*8/1024)+ROUND((AVG_ROW_LEN * NUM_ROWS / (1024 * 1024)), 2)) RESERV
from all_tables
where OWNER like '[SCHEMA_NAME]'
and NUM_ROWS > 1
order by 4,6 desc;--sgc