What is the Tablespace in Oracle

I will explain What is the Tablespace in Oracle in this post.

What is the Tablespace in Oracle

You should read the following articles, if you don’t know Oracle database architecture.

Oracle Database Architecture -3 SMON, PMON, DBWR,CKPT and LGWR Processes

The units of Oracle database space allocation are data blocks, extents, and segments.

Oracle stores data in data blocks and set of data blocks are called as Extents.

A segment is a set of extents and each table and index is a segment in Oracle database.

Relationships Among Segments, Extents, and Data Blocks are as shown below.

Tablespace in Oracle

Tablespaces are logical storage units which are comprised of one or more datafiles. Datafiles are physical storage units that stores the database’s data collectively.

Tablespaces are consist of tables and indexes.

Relationships Among Tablespace, Datafile, Table and index are as shown below.

When you install and create a new Oracle database, it has 5 default tablespaces as follows.

• SYSTEM
• USERS
• UNDOTBS
• TEMP
• SYSAUX

You should use new tablespaces except these, You can create a new permanent tablespace as follows.

If you are using file system for Oracle Storage, then you can use it following script.

CREATE TABLESPACE NEW_TBS_TEST
DATAFILE
'/oracle/oradata/TEST/NEW_TBS_TEST01.dbf' SIZE 4G AUTOEXTEND ON NEXT 200M MAXSIZE UNLIMITED,
'/oracle/oradata/TEST/NEW_TBS_TEST02.dbf' SIZE 4G AUTOEXTEND ON NEXT 200M MAXSIZE UNLIMITED
LOGGING
ONLINE
EXTENT MANAGEMENT LOCAL AUTOALLOCATE
BLOCKSIZE 8K
SEGMENT SPACE MANAGEMENT AUTO
FLASHBACK ON;

If you are using the Oracle ASM , then you can use it following script.

CREATE TABLESPACE NEW_TBS_TEST
DATAFILE
'+DATA' SIZE 4G AUTOEXTEND ON NEXT 200M MAXSIZE UNLIMITED
LOGGING
ONLINE
EXTENT MANAGEMENT LOCAL AUTOALLOCATE
BLOCKSIZE 8K
SEGMENT SPACE MANAGEMENT AUTO
FLASHBACK ON;

If you want to create temporary (temp) tablespace, you can create it as follows, if you use Oracle ASM.

CREATE TEMPORARY TABLESPACE TEMP2 TEMPFILE 
'+DATAC1' SIZE 100M AUTOEXTEND ON NEXT 1024M MAXSIZE UNLIMITED
TABLESPACE GROUP ''
EXTENT MANAGEMENT LOCAL UNIFORM SIZE 1M;

If you use File system, you can create the temp tablespace as follows.

CREATE TEMPORARY TABLESPACE TEMP2 TEMPFILE 
''/oracle/oradata/TEST/TEMP02.dbf' SIZE 100M AUTOEXTEND ON NEXT 1024M MAXSIZE UNLIMITED
TABLESPACE GROUP ''
EXTENT MANAGEMENT LOCAL UNIFORM SIZE 1M;

If you want to create undo tablespace, you can create it as follows, if you use Oracle ASM.

CREATE UNDO TABLESPACE UNDO2 DATAFILE 
'+DATAC1' SIZE 100M AUTOEXTEND ON NEXT 1024M MAXSIZE UNLIMITED
RETENTION NOGUARANTEE
BLOCKSIZE 8K
FLASHBACK ON;

If you use File system, you can create the undo tablespace as follows.

CREATE UNDO TABLESPACE UNDO2 DATAFILE 
'/oracle/oradata/TEST/UNDO02.dbf' SIZE 100M AUTOEXTEND ON NEXT 1024M MAXSIZE UNLIMITED
TABLESPACE GROUP ''
EXTENT MANAGEMENT LOCAL UNIFORM SIZE 1M;

If you want to create bigfile tablespace, you can create it as follows, if you use Oracle ASM.

CREATE BIGFILE TABLESPACE BIGTABLESPACE DATAFILE 
'+DATAC1' SIZE 100M AUTOEXTEND ON NEXT 1024M MAXSIZE 34359738344K
LOGGING
EXTENT MANAGEMENT LOCAL AUTOALLOCATE
BLOCKSIZE 8K
SEGMENT SPACE MANAGEMENT AUTO
FLASHBACK ON;

You can add new datafile to the tablespace , If Oracle ASM is used, you can use the following script.

ALTER TABLESPACE NEW_TBS_TEST ADD DATAFILE '+DATA' SIZE 15M AUTOEXTEND ON MAXSIZE UNLIMITED;

You can add new datafile to the tablespace , If File System is used, you can use the following script.

ALTER TABLESPACE NEW_TBS_TEST ADD DATAFILE '/oracle/oradata/TEST/NEW_TBS_TEST03.dbf' SIZE 15M AUTOEXTEND ON MAXSIZE UNLIMITED;

You can check and query the usage of tablespaces with the following script.

set pagesize 1000 linesize 180
tti 'Tablespace Usage Status'
col "TOTAL(MB)" for 99,999,999.999
col "USAGE(MB)" for 99,999,999.999
col "FREE(MB)" for 99,999,999.999
col "EXTENSIBLE(MB)" for 99,999,999.999
col "FREE PCT %" for 999.99
col "USED PCT OF MAX %" for 999.99
col "NOTO" for 9999
col "OTO" for 999
select d.tablespace_name "ADI",
d.contents "TIPI",
nvl(a.bytes /1024/1024,0) "TOTAL(MB)",
nvl(a.bytes - nvl(f.bytes,0),0)/1024/1024 "USAGE(MB)",
nvl(f.bytes,0)/1024/1024 "FREE(MB)",
nvl((a.bytes - nvl(f.bytes,0))/a.bytes * 100,0) "FREE PCT %",
nvl(a.ARTACAK,0)/1024/1024 "EXTENSIBLE(MB)",
nvl((a.bytes - nvl(f.bytes,0))/ (a.bytes + nvl(a.ARTACAK,0)) * 100,0) "USED PCT OF MAX %",
a.NOTO, a.OTO
from sys.dba_tablespaces d,
(select tablespace_name, sum(bytes) bytes,
sum(decode(autoextensible,'YES',MAXbytes - bytes,0 )) ARTACAK,
count(decode(autoextensible,'NO',0)) NOTO,
count(decode(autoextensible,'YES',0)) OTO
from dba_data_files
group by tablespace_name) a,
(select tablespace_name, sum(bytes) bytes
from dba_free_space
group by tablespace_name) f
where d.tablespace_name = a.tablespace_name(+)
and d.tablespace_name = f.tablespace_name(+)
and NOT (d.extent_management like 'LOCAL'and d.contents like 'TEMPORARY')
UNION ALL
select d.tablespace_name "ADI",
d.contents "TIPI",
nvl(a.bytes /1024/1024,0) "TOTAL(MB)",
nvl(t.bytes,0)/1024/1024 "USAGE(MB)",
nvl(a.bytes - nvl(t.bytes,0),0)/1024/1024 "FREE(MB)",
nvl(t.bytes/a.bytes * 100,0) "FREE PCT %",
nvl(a.ARTACAK,0)/1024/1024 "EXTENSIBLE(MB)",
nvl(t.bytes/(a.bytes + nvl(a.ARTACAK,0)) * 100,0) "USED PCT OF MAX %", a.NOTO, a.OTO
from sys.dba_tablespaces d,
(select tablespace_name, sum(bytes) bytes,
sum(decode(autoextensible,'YES',MAXbytes - bytes,0 )) ARTACAK,
count(decode(autoextensible,'NO',0)) NOTO,
count(decode(autoextensible,'YES',0)) OTO
from dba_temp_files
group by tablespace_name) a,
(select tablespace_name, sum(bytes_used) bytes
from v$temp_extent_pool
group by tablespace_name) t
where d.tablespace_name = a.tablespace_name(+)
and d.tablespace_name = t.tablespace_name(+)
and d.extent_management like 'LOCAL'
and d.contents like 'TEMPORARY%'
order by 3 desc;
exit;

The result of script is as follows.

                                                    Tablespace Usage Status

NAME                           TYPE            TOTAL(MB)       USAGE(MB)        FREE(MB) FREE PCT %  EXTENSIBLE(MB) USED PCT OF MAX %
------------------------------ --------- --------------- --------------- --------------- ---------- --------------- -----------------
UNDOTBS1                       UNDO           32,767.984         489.984      32,278.000       1.50            .000              1.50
STATSPACK                      PERMANENT      30,510.000       8,876.750      21,633.250      29.09       2,257.984             27.09
SYSTEM                         PERMANENT      30,360.000       7,488.000      22,872.000      24.66       2,407.984             22.85
TEMP                           TEMPORARY      13,110.000          42.000      13,068.000        .32      19,657.984               .13
SYSAUX                         PERMANENT       1,320.000       1,251.125          68.875      94.78      31,447.984              3.82
USERS                          PERMANENT           5.000           1.313           3.688      26.25      32,762.984               .00

Do you want to learn Oracle Database for Beginners, then read the following articles.

Oracle Tutorial | Oracle Database Tutorials for Beginners ( Junior Oracle DBA )