Tablespace Fragmentation. specially in SYSTEM tablesapce.

Question

Hi,
I am working on Oracle 11gR2 DB and AIX OS.
An database is having many tablespaces which are allocated to specific schemas. These schemas are functional from a long time. Data comes and goes all the time. The size of the tablespace has gone very high(than expected). We have removed(truncated) most of the unwanted tables and data from the schema and trying to resize the datafile, but we are not able to do it.
while checking with the below query :-
SELECT   df.tablespace_name "Tablespace",
       df.bytes / (1024 * 1024) "Size (MB)",
       SUM(fs.bytes) / (1024 * 1024) "Free (MB)",
       Nvl(Round(SUM(fs.bytes) * 100 / df.bytes),1) "% Free",
       Round((df.bytes - SUM(fs.bytes)) * 100 / df.bytes) "% Used"
  FROM dba_free_space fs,
       (SELECT tablespace_name,SUM(bytes) bytes
          FROM dba_data_files
         GROUP BY tablespace_name) df
WHERE fs.tablespace_name (+)  = df.tablespace_name
GROUP BY df.tablespace_name,df.bytes
UNION ALL
SELECT df.tablespace_name tspace,
       fs.bytes / (1024 * 1024),
       SUM(df.bytes_free) / (1024 * 1024),
       Nvl(Round((SUM(fs.bytes) - df.bytes_used) * 100 / fs.bytes), 1),
       Round((SUM(fs.bytes) - df.bytes_free) * 100 / fs.bytes)
  FROM dba_temp_files fs,
       (SELECT tablespace_name,bytes_free,bytes_used
          FROM v$temp_space_header
         GROUP BY tablespace_name,bytes_free,bytes_used) df
WHERE fs.tablespace_name (+)  = df.tablespace_name
GROUP BY df.tablespace_name,fs.bytes,df.bytes_free,df.bytes_used
ORDER BY 4 DESC;
The output is :-
tablespace name         size_MB    free_space_MB     %free  %used
  SYSTEM                34256     28941.375        84            16
   SMD                      7975     2991.1875        38            62
.................N many other Here if i try to resize the SMD tablespace datafile to (7975-2991.1875) 4983 MB it does not allow me to do it.
Also the SYSTEM tablespace has gone so big but used space is very less.
I suspect that fragmentation is the problem here._
Please guide me what could i do in these case to reduce the space taken by the datafiles.
Thanks in advance.

Answer 1

Thanks for notifying......I have a misconception about it...both the queries giving almost same result.
but first query give you result at datafile level.
SQL> column tablespace_name format a10
SQL> column file_name format a32
SQL> column file_mb format 9999990
SQL> column hwm_mb format 9999990
SQL> column used_mb format 9999990
SQL> column shrnk_mb format 9999990
SQL>
SQL> break on report
SQL> compute sum of file_mb on report
SQL> compute sum of hwm_mb on report
SQL> compute sum of used_mb on report
SQL> compute sum of shrnk_mb on report
SQL>
SQL> select a.*
  2  , file_mb-hwm_mb shrnk_mb
  3  from (
  4  select /*+ rule */
  5  a.tablespace_name,
  6  a.file_name,
  7  a.bytes/1024/1024 file_mb,
  8  b.hwm*d.block_size/1024/1024 hwm_mb,
  9  b.used*d.block_size/1024/1024 used_mb
10  from
11  dba_data_files a,
12  (select file_id,max(block_id+blocks-1) hwm,sum(blocks) used
13  from dba_extents
14  group by file_id) b,
15  dba_tablespaces d
16  where a.file_id = b.file_id
17  and a.tablespace_name = d.tablespace_name
18  ) a
19  order by a.tablespace_name,a.file_name;
TABLESPACE FILE_NAME                         FILE_MB   HWM_MB  USED_MB SHRNK_MB
SYSAUX     C:\ORACLEXE\APP\ORACLE\ORADATA\X      710      673      672       37
           E\UNDOTBS1.DBF
SYSTEM     C:\ORACLEXE\APP\ORACLE\ORADATA\X      360      353      352        7
           E\SYSTEM.DBF
UNDOTBS1   C:\ORACLEXE\APP\ORACLE\ORADATA\X      260      258      257        2
           E\SYSAUX.DBF
USERS      C:\ORACLEXE\APP\ORACLE\ORADATA\X     6340     6017     6016      323
           E\USERS.DBF
TABLESPACE FILE_NAME                         FILE_MB   HWM_MB  USED_MB SHRNK_MB
sum                                             7670     7301     7296      369
SQL> SELECT /* + RULE */  df.tablespace_name "Tablespace",
  2         df.bytes / (1024 * 1024) "Size (MB)",
  3         SUM(fs.bytes) / (1024 * 1024) "Free (MB)",
  4         Nvl(Round(SUM(fs.bytes) * 100 / df.bytes),1) "% Free",
  5         Round((df.bytes - SUM(fs.bytes)) * 100 / df.bytes) "% Used"
  6    FROM dba_free_space fs,
  7         (SELECT tablespace_name,SUM(bytes) bytes
  8            FROM dba_data_files
  9           GROUP BY tablespace_name) df
10   WHERE fs.tablespace_name (+)  = df.tablespace_name
11   GROUP BY df.tablespace_name,df.bytes
12  UNION ALL
13  SELECT /* + RULE */ df.tablespace_name tspace,
14         fs.bytes / (1024 * 1024),
15         SUM(df.bytes_free) / (1024 * 1024),
16         Nvl(Round((SUM(fs.bytes) - df.bytes_used) * 100 / fs.bytes), 1),
17         Round((SUM(fs.bytes) - df.bytes_free) * 100 / fs.bytes)
18    FROM dba_temp_files fs,
19         (SELECT tablespace_name,bytes_free,bytes_used
20            FROM v$temp_space_header
21           GROUP BY tablespace_name,bytes_free,bytes_used) df
22   WHERE fs.tablespace_name (+)  = df.tablespace_name
23   GROUP BY df.tablespace_name,fs.bytes,df.bytes_free,df.bytes_used
24   ORDER BY 4 DESC;
Tablespace                      Size (MB)  Free (MB)     % Free     % Used
TEMP                                   20         17         85         15
USERS                                6340   323.3125          5         95
SYSAUX                                710      37.25          5         95
SYSTEM                                360     7.3125          2         98
UNDOTBS1                              260     1.8125          1         99
SQL>