Tablespace in Oracle Posted by MOHAMMED ABDUL HAMEED on 12:23 AM

A Tablespace is a container for segments (tables, indexes, etc). A database consists of one or more tablespaces, each made up of one or more data files. Tables and indexes are created within a particular tablespace.

When a New database is created, it will have the following tablespaces :

SYSTEM (the data dictionary)
SYSAUX (optional database components)
TEMP (temporary tablespace)
UNDOTBS1 (undo tablespace, contains pre image data)
USERS (default users tablespace created)

Syntax :

Create tablespace
Datafile '/u01/home/prd/cmm.dbf' size 100m 
autoextend on 
next 100m maxsize unlimited;

Check Free/Used space per tablespace :

SELECT /* + RULE */  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 /* + RULE */ 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;

Sample output:

Tablespace                      Size (MB)  Free (MB)     % Free     % Used
------------------------------ ---------- ---------- ---------- -----------------
    UNDOTBS1                               65    17.8125         27         73
     EXAMPLE                               100     22.625         23         75
    USERS                                         5     1.0625         21         79
    TEMP                                         20          2             10         90
   SYSAUX                               625.125     304.5        48      52
   SYSTEM                                  700     9.0625          1         99