Tablespace Data Dictionary Views

The following data dictionary and dynamic performance views provide useful information about the tablespaces of a database.

View	Description
`V$TABLESPACE`	Name and number of all tablespaces from the control file.
`V$ENCRYPTED_TABLESPACES`	Name and encryption algorithm of all encrypted tablespaces.
`DBA_TABLESPACES`, `USER_TABLESPACES`	Descriptions of all (or user accessible) tablespaces.
`DBA_TABLESPACE_GROUPS`	Displays the tablespace groups and the tablespaces that belong to them.
`DBA_SEGMENTS`, `USER_SEGMENTS`	Information about segments within all (or user accessible) tablespaces.
`DBA_EXTENTS`, `USER_EXTENTS`	Information about data extents within all (or user accessible) tablespaces.
`DBA_FREE_SPACE`, `USER_FREE_SPACE`	Information about free extents within all (or user accessible) tablespaces.
`DBA_TEMP_FREE_SPACE`	Displays the total allocated and free space in each temporary tablespace.
`V$DATAFILE`	Information about all datafiles, including tablespace number of owning tablespace.
`V$TEMPFILE`	Information about all tempfiles, including tablespace number of owning tablespace.
`DBA_DATA_FILES`	Shows files (datafiles) belonging to tablespaces.
`DBA_TEMP_FILES`	Shows files (tempfiles) belonging to temporary tablespaces.
`V$TEMP_EXTENT_MAP`	Information for all extents in all locally managed temporary tablespaces.
`V$TEMP_EXTENT_POOL`	For locally managed temporary tablespaces: the state of temporary space cached and used for by each instance.
`V$TEMP_SPACE_HEADER`	Shows space used/free for each tempfile.
`DBA_USERS`	Default and temporary tablespaces for all users.
`DBA_TS_QUOTAS`	Lists tablespace quotas for all users.
`V$SORT_SEGMENT`	Information about every sort segment in a given instance. The view is only updated when the tablespace is of the `TEMPORARY` type.
`V$TEMPSEG_USAGE`	Describes temporary (sort) segment usage by user for temporary or permanent tablespaces.

The following are just a few examples of using some of these views.

Example 1: Listing Tablespaces and Default Storage Parameters

To list the names and default storage parameters of all tablespaces in a database, use the following query on the DBA_TABLESPACES view:

SELECT TABLESPACE_NAME "TABLESPACE",
   INITIAL_EXTENT "INITIAL_EXT",
   NEXT_EXTENT "NEXT_EXT",
   MIN_EXTENTS "MIN_EXT",
   MAX_EXTENTS "MAX_EXT",
   PCT_INCREASE
   FROM DBA_TABLESPACES;

TABLESPACE  INITIAL_EXT  NEXT_EXT  MIN_EXT   MAX_EXT    PCT_INCREASE  
----------  -----------  --------  -------   -------    ------------ 
RBS             1048576   1048576        2        40               0
SYSTEM           106496    106496        1        99               1
TEMP             106496    106496        1        99               0
TESTTBS           57344     16384        2        10               1
USERS             57344     57344        1        99               1

Example 2: Listing the Datafiles and Associated Tablespaces of a Database

To list the names, sizes, and associated tablespaces of a database, enter the following query on the DBA_DATA_FILES view:

SELECT  FILE_NAME, BLOCKS, TABLESPACE_NAME
   FROM DBA_DATA_FILES;

FILE_NAME                                      BLOCKS  TABLESPACE_NAME
------------                               ----------  -------------------
/U02/ORACLE/IDDB3/DBF/RBS01.DBF                  1536  RBS
/U02/ORACLE/IDDB3/DBF/SYSTEM01.DBF               6586  SYSTEM
/U02/ORACLE/IDDB3/DBF/TEMP01.DBF                 6400  TEMP
/U02/ORACLE/IDDB3/DBF/TESTTBS01.DBF              6400  TESTTBS
/U02/ORACLE/IDDB3/DBF/USERS01.DBF                 384  USERS

Example 3: Displaying Statistics for Free Space (Extents) of Each Tablespace

To produce statistics about free extents and coalescing activity for each tablespace in the database, enter the following query:

SELECT TABLESPACE_NAME "TABLESPACE", FILE_ID,
   COUNT(*)    "PIECES",
   MAX(blocks) "MAXIMUM",
   MIN(blocks) "MINIMUM",
   AVG(blocks) "AVERAGE",
   SUM(blocks) "TOTAL"
   FROM DBA_FREE_SPACE
GROUP BY TABLESPACE_NAME, FILE_ID;

TABLESPACE    FILE_ID  PIECES   MAXIMUM    MINIMUM  AVERAGE    TOTAL
----------    -------  ------   -------    -------  -------   ------
RBS                 2       1       955        955      955      955
SYSTEM              1       1       119        119      119      119
TEMP                4       1      6399       6399     6399     6399
TESTTBS             5       5      6364          3     1278     6390
USERS               3       1       363        363      363      363

PIECES shows the number of free space extents in the tablespace file, MAXIMUM and MINIMUM show the largest and smallest contiguous area of space in database blocks, AVERAGE shows the average size in blocks of a free space extent, and TOTAL shows the amount of free space in each tablespace file in blocks. This query is useful when you are going to create a new object or you know that a segment is about to extend, and you want to make sure that there is enough space in the containing tablespace.