Oracle DBA FAQ - Managing Oracle Tablespaces and Data Files

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A collection of 19 FAQs on creating and managing tablespaces and data files. Clear answers are provided with tutorial exercises on creating and dropping tablespaces; listing available tablespaces; creating and dropping data files; setting tablespaces and data files offline; removing corrupted data files. Topics included in this FAQ are:

What Is an Oracle Tablespace?
What Is an Oracle Data File?
How a Tablespace Is Related to Data Files?
How a Database Is Related to Tablespaces?
How To View the Tablespaces in the Current Database?
What Are the Predefined Tablespaces in a Database?
How To View the Data Files in the Current Database?
How To Create a new Oracle Data File?
How To Create a New Tablespace?
How To Rename a Tablespace?
How To Drop a Tablespace?
What Happens to the Data Files If a Tablespace Is Dropped?
How To Create a Table in a Specific Tablespace?
How To See Free Space of Each Tablespace?
How To Bring a Tablespace Offline?
How To Bring a Tablespace Online?
How To Add Another Datafile to a Tablespace?
What Happens If You Lost a Data File?
How Remove Data Files befor opening a Database?

Sample scripts used in this FAQ assumes that you are connected to the server with the SYSTEM user account on the default database instance XE. See other FAQ collections on how to connect to the server.

What Is an Oracle Tablespace?

An Oracle tablespace is a big unit of logical storage in an Oracle database. It is managed and used by the Oracle server to store structures data objects, like tables and indexes.

What Is an Oracle Data File?

An Oracle data file is a big unit of physical storage in the OS file system. One or many Oracle data files are organized together to provide physical storage to a single Oracle tablespace.

How a Tablespace Is Related to Data Files?

Each tablespace in an Oracle database consists of one or more files called datafiles, which are physical structures that conform to the operating system in which Oracle is running.

How a Database Is Related to Tablespaces?

A database's data is collectively stored in the datafiles that constitute each tablespace of the database. For example, the simplest Oracle database would have one tablespace and one datafile. Another database can have three tablespaces, each consisting of two datafiles (for a total of six datafiles).

How To View the Tablespaces in the Current Database?

If you want to get a list of all tablespaces used in the current database instance, you can use the DBA_TABLESPACES view as shown in the following SQL script example:

SQL> connect SYSTEM/fyicenter
Connected.

SQL> SELECT TABLESPACE_NAME, STATUS, CONTENTS
  2  FROM USER_TABLESPACES;
TABLESPACE_NAME                STATUS    CONTENTS
------------------------------ --------- ---------
SYSTEM                         ONLINE    PERMANENT
UNDO                           ONLINE    UNDO
SYSAUX                         ONLINE    PERMANENT
TEMP                           ONLINE    TEMPORARY
USERS                          ONLINE    PERMANENT

What Are the Predefined Tablespaces in a Database?

When you create a new database, Oracle server will create 4 required tablespaces for the new database:

SYSTEM Tablespace - Every Oracle database contains a tablespace named SYSTEM, which Oracle creates automatically when the database is created. The SYSTEM tablespace is always online when the database is open.
SYSAUX Tablespace - The SYSAUX tablespace was installed as an auxiliary tablespace to the SYSTEM tablespace when you created your database. Some database components that formerly created and used separate tablespaces now occupy the SYSAUX tablespace.
UNDO Tablespace - UNDO tablespaces are special tablespaces used solely for storing undo information. You cannot create any other segment types (for example, tables or indexes) in undo tablespaces. Each database contains zero or more undo tablespaces. In automatic undo management mode, each Oracle instance is assigned one (and only one) undo tablespace. Undo data is managed within an undo tablespace using undo segments that are automatically created and maintained by Oracle.
TEMP Tablespace - When the SYSTEM tablespace is locally managed, you must define at least one default temporary tablespace when creating a database. A locally managed SYSTEM tablespace cannot be used for default temporary storage.

How To View the Data Files in the Current Database?

If you want to get a list of all tablespaces used in the current database instance, you can use the DBA_TABLESPACES view as shown in the following SQL script example:

SQL> connect SYSTEM/fyicenter
Connected.

SQL> col tablespace_name format a16;
SQL> col file_name format a36;
SQL> SELECT TABLESPACE_NAME, FILE_NAME, BYTES
  2  FROM DBA_DATA_FILES;
TABLESPACE_NAME FILE_NAME                           BYTES
--------------- ------------------------------- ---------
USERS           \ORACLEXE\ORADATA\XE\USERS.DBF  104857600
SYSAUX          \ORACLEXE\ORADATA\XE\SYSAUX.DBF 461373440
UNDO            \ORACLEXE\ORADATA\XE\UNDO.DBF    94371840
SYSTEM          \ORACLEXE\ORADATA\XE\SYSTEM.DBF 356515840

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