Dealocate Unusd Extent

SQL> analyze table scott.emp compute statistics;

Table analyzed.

SQL> select num_rows,AVG_ROW_LEN

from dba_tables

where table_name='EMP';

NUM_ROWS AVG_ROW_LEN

---------- -----------

14 40

SQL> SELECT table_name, initial_extent, next_extent,

max_extents, num_rows,pct_free

FROM dba_tables

WHERE table_name = 'EMP';

TABLE_NAME INITIAL_EXTENT NEXT_EXTENT MAX_EXTENTS NUM_ROWS PCT_FREE

--------------- -------------- ----------- ----------- ---------- -------------------------------------------------------------------------------

EMP 65536 2147483645 14 10

SQL> SELECT BYTES

FROM DBA_SEGMENTS

WHERE SEGMENT_NAME='EMP';

BYTES

----------

65536

SQL> ALTER TABLE SCOTT.EMP ALLOCATE EXTENT;

Table altered.

SQL> analyze table scott.emp compute statistics;

Table analyzed.

SQL> SELECT BYTES

FROM DBA_SEGMENTS

WHERE SEGMENT_NAME='EMP';

BYTES

----------

131072

SQL> ALTER TABLE SCOTT.EMP DEALLOCATE UNUSED;

Table altered.

SQL> SELECT BYTES

FROM DBA_SEGMENTS

WHERE SEGMENT_NAME='EMP';

BYTES

----------

65536