Oracle related statistics

--1. Check the size of each table space 
SELECT TABLESPACE_NAME,
       SUM( BYTES )/ 1024 / 1024
       || ' MB'
FROM DBA_SEGMENTS
GROUP BY TABLESPACE_NAME;

--2. The amount of physical space allocated by the query table 
SELECT SEGMENT_NAME,
       SUM( BYTES )/ 1024 / 1024  Allocate space MB
FROM USER_EXTENTS
GROUP BY SEGMENT_NAME
ORDER BY  Allocate space MB DESC;

--3. Query the actual amount of space used 
SELECT TABLE_NAME                                 Table name ,
       NUM_ROWS                                   Data volume ,
       AVG_ROW_LEN                                Average size of each ,
       ( NUM_ROWS * AVG_ROW_LEN / 1024 / 1024 )   Occupancy space MB
FROM USER_TABLES
ORDER BY  Occupancy space MB DESC;

--4. View the remaining tablespace size  
SELECT TABLESPACE_NAME                   Table space ,
       SUM( BLOCKS * 8192 / 1000000 )    Remaining space M
FROM DBA_FREE_SPACE
GROUP BY TABLESPACE_NAME;

--5. Check the overall space of all tablespaces in the system 
SELECT B.NAME,
       SUM( A.BYTES / 1000000 ) Total space 
FROM V$DATAFILE    A,
     V$TABLESPACE  B
WHERE A.TS# = B.TS#
GROUP BY B.NAME;

--6. Check table space utilization 
SELECT 　　A.A1                                 Tablespace name ,
       　　C.C2                                 type ,
       　　C.C3                                 District Management ,
       　　B.B2 / 1024 / 1024                   Table space size M,
       　　( B.B2 - A.A2 )/ 1024 / 1024         Already used M,
       　　SUBSTR(( B.B2 - A.A2 )/ B.B2 * 100,1,5)|| '%'  utilization 
FROM
　　(select tablespace_name a1, sum(nvl(bytes,0)) a2 from dba_free_space group by tablespace_name) a,
　　(select tablespace_name b1,sum(bytes) b2 from dba_data_files group by tablespace_name) b,
　　(select tablespace_name c1,contents c2,extent_management c3 from dba_tablespaces) c
WHERE A.A1 = B.B1
AND C.C1 = B.B1;

--7. Data file size and usage 
SELECT 　　B.FILE_NAME               Physical file name ,
       　　B.TABLESPACE_NAME         Table space ,
       　　B.BYTES / 1024 / 1024     size M,
       　　( B.BYTES - SUM( NVL(A.BYTES,0)))/ 1024 / 1024   Already used M,
       　　SUBSTR(( B.BYTES - SUM( NVL(A.BYTES,0)))/( B.BYTES )* 100,1,5)|| '%'  utilization 
from dba_free_space a,dba_data_files b
where a.file_id=b.file_id
group BY B.TABLESPACE_NAME,B.FILE_NAME,B.BYTES 　　
ORDER BY B.TABLESPACE_NAME; 

--8. Inquire about oracle Table space usage 
select b.file_id　　 file ID,
        b.tablespace_name　　 Table space ,
        b.file_name　　　　　 Physical file name ,
        b.bytes　　　　　　　 Total bytes ,
        (b.bytes-sum(nvl(a.bytes,0)))　　　 Already used ,
        sum(nvl(a.bytes,0))　　　　　　　　 The remaining ,
        sum(nvl(a.bytes,0))/(b.bytes)*100　 The remaining percentage 
from dba_free_space a,dba_data_files b
where a.file_id=b.file_id
group by b.tablespace_name,b.file_name,b.file_id,b.bytes
order by b.tablespace_name

--9. see SYS_LOB* Which table does the file belong to 
SELECT B.TABLE_NAME,
       B.COLUMN_NAME,
       A.SEGMENT_NAME,
       a.SEGMENT_TYPE,
       ROUND(SUM(A.BYTES / 1024 / 1024 / 1024), 2) G
FROM DBA_SEGMENTS A
LEFT JOIN DBA_LOBS B ON A.OWNER = B.OWNER AND A.SEGMENT_NAME = B.SEGMENT_NAME
WHERE B.SEGMENT_NAME = 'SYS_LOB0021914268C00014$$'
GROUP BY B.TABLE_NAME, B.COLUMN_NAME, A.SEGMENT_NAME,a.SEGMENT_TYPE;