Como calcular el tamaño realmente usado de un segmento

Con este script se puede calcular el tamaño realmente usado por un segmento.


PROMPT
PROMPT SEGMENT SPACE ALLOCATION
PROMPT

ACCEPT own PROMPT "Segment owner: "
ACCEPT obj PROMPT "Segment name: "
ACCEPT typ PROMPT "Segment type ((T)able, (I)ndex or (C)luster) or (L)ob: "

SET HEADING OFF
SELECT ' ' FROM sys.dual;

SET SERVEROUTPUT ON

DECLARE

op1 NUMBER;
op2 NUMBER;
op3 NUMBER;
op4 NUMBER;
op5 NUMBER;
op6 NUMBER;
op7 NUMBER;
obj_type VARCHAR2(10);
file_name VARCHAR2(255);
ts_name VARCHAR2(30);

BEGIN

IF UPPER('&typ') = 'T' THEN

obj_type := 'TABLE';

ELSIF UPPER('&typ') = 'I' THEN

obj_type := 'INDEX';

ELSIF UPPER('&typ') = 'C' THEN

obj_type := 'CLUSTER';

ELSIF UPPER('&typ') = 'L' THEN

obj_type := 'LOB';

ELSE
dbms_output.put_line('Invalid object type');
RETURN;
END IF;

dbms_space.unused_space(
UPPER('&own'),
UPPER('&obj'),
obj_type,
op1, op2, op3, op4, op5, op6, op7
);

dbms_output.put_line('Total Blocks = ' || op1);
dbms_output.put_line('Total Bytes = ' || op2);
dbms_output.put_line('Unused Blocks = ' || op3);
dbms_output.put_line('Unused Bytes = ' || op4);

SELECT file_name, tablespace_name
INTO file_name, ts_name
FROM dba_data_files
WHERE file_id = op5;

dbms_output.put_line('Segment Tablespace = ' || ts_name);
dbms_output.put_line('Last Used Extent File ID = ' || op5);
dbms_output.put_line('Last Used Extent File = ' || file_name);
dbms_output.put_line('Last Used Extent Block ID = ' || op6);
dbms_output.put_line('Last Used Block = ' || op7);

END;
/

UNDEFINE obj
UNDEFINE own
UNDEFINE typ