Hi Sudhir
Here is a query to start off with that will give you the top 20 tables with the most fragmented space where you could gain the most space
SELECT * FROM
(SELECT
SUBSTR(TABLE_NAME, 1, 21) TABLE_NAME,
NUM_ROWS,
AVG_ROW_LEN ROWLEN,
BLOCKS,
ROUND((AVG_ROW_LEN + 1) * NUM_ROWS / 1000000, 0) NET_MB,
ROUND(BLOCKS * (8000 - 23 * INI_TRANS) *
(1 - PCT_FREE / 100) / 1000000, 0) GROSS_MB,
ROUND((BLOCKS * (8000 - 23 * INI_TRANS) * (1 - PCT_FREE / 100) -
(AVG_ROW_LEN + 1) * NUM_ROWS) / 1000000) "WASTED_MB"
FROM DBA_TABLES
WHERE
NUM_ROWS IS NOT NULL AND
OWNER LIKE 'SAP%' AND
PARTITIONED = 'NO' AND
(IOT_TYPE != 'IOT' OR IOT_TYPE IS NULL)
ORDER BY 7 DESC)
WHERE ROWNUM <=20;
Once the list has been obtained you can reorg the table using BRTOOLS
http://help.sap.com/saphelp_nw04/helpdata/en/1b/4e8f0d38a8f4419436d608a36b6581/content.htm
You can also do some research on oracle shrink command
http://www.oracle.com/technetwork/issue-archive/2005/05-may/o35tuning-096075.html
Hope this helps
Best Regards
Marius