DROP TABLESPACE

Purpose

Use the DROP TABLESPACE statement to remove a tablespace from the database.

When you drop a tablespace, Oracle Database does not place it in the recycle bin. Therefore, you cannot subsequently either purge or undrop the tablespace.

Prerequisites

You must have the DROP TABLESPACE system privilege. You cannot drop a tablespace if it contains any rollback segments holding active transactions.

Syntax

drop_tablespace::=

Description of the illustration drop_tablespace.gif

Semantics

tablespace

Specify the name of the tablespace to be dropped.

You can drop a tablespace regardless of whether it is online or offline. Oracle recommends that you take the tablespace offline before dropping it to ensure that no SQL statements in currently running transactions access any of the objects in the tablespace.

You cannot drop the SYSTEM tablespace. You can drop the SYSAUX tablespace only if you have the SYSDBA system privilege and you have started the database in MIGRATE mode.

You may want to alert any users who have been assigned the tablespace as either a default or temporary tablespace. After the tablespace has been dropped, these users cannot allocate space for objects or sort areas in the tablespace. You can reassign users new default and temporary tablespaces with the ALTER USER statement.

Any objects that were previously dropped from the tablespace and moved to the recycle bin are purged from the recycle bin. Oracle Database removes from the data dictionary all metadata about the tablespace and all datafiles and tempfiles in the tablespace. The database also automatically drops from the operating system any Oracle-managed datafiles and tempfiles in the tablespace. Other datafiles and tempfiles are not removed from the operating system unless you specify INCLUDING CONTENTS AND DATAFILES.

You cannot use this statement to drop a tablespace group. However, if tablespace is the only tablespace in a tablespace group, then Oracle Database removes the tablespace group from the data dictionary as well.

Restrictions on Dropping Tablespaces Dropping tablespaces is subject to the following restrictions:

• You cannot drop a tablespace that contains a domain index or any objects created by a domain index.

• You cannot drop an undo tablespace if it is being used by any instance or if it contains any undo data needed to roll back uncommitted transactions.

• You cannot drop a tablespace that has been designated as the default tablespace for the database. You must first reassign another tablespace as the default tablespace and then drop the old default tablespace.

• You cannot drop a temporary tablespace if it is part of the database default temporary tablespace group. You must first remove the tablespace from the database default temporary tablespace group and then drop it.

• You cannot drop a tablespace, even with the INCLUDING CONTENTS and CASCADE CONSTRAINTS clauses, if doing so would disable a primary key or unique constraint in another tablespace. For example, if the tablespace being dropped contains a primary key index, but the primary key column itself is in a different tablespace, then you cannot drop the tablespace until you have manually disabled the primary key constraint in the other tablespace.

INCLUDING CONTENTS

Specify INCLUDING CONTENTS to drop all the contents of the tablespace. You must specify this clause to drop a tablespace that contains any database objects. If you omit this clause, and the tablespace is not empty, then the database returns an error and does not drop the tablespace.

For partitioned tables, DROP TABLESPACE will fail even if you specify INCLUDING CONTENTS, if the tablespace contains some, but not all:

• Partitions of a range- or hash-partitioned table, or

• Subpartitions of a composite-partitioned table.

For a partitioned index-organized table, if all the primary key index segments are in this tablespace, then this clause will also drop any overflow segments that exist in other tablespaces, as well as any associated mapping table in other tablespaces. If some of the primary key index segments are not in this tablespace, then the statement will fail. In that case, before you can drop the tablespace, you must use ALTER TABLE ... MOVE PARTITION to move those primary key index segments into this tablespace, drop the partitions whose overflow data segments are not in this tablespace, and drop the partitioned index-organized table.

If the tablespace contains a master table of a materialized view, then the database invalidates the materialized view.

If the tablespace contains a materialized view log, then the database drops the log and any other direct-path INSERT refresh information associated with the table.

AND DATAFILES

When you specify INCLUDING CONTENTS, the AND DATAFILES clause lets you instruct the database to delete the associated operating system files as well. Oracle Database writes a message to the alert log for each operating system file deleted. This clause is not needed for Oracle-managed files, because they are removed from the system even if you do not specify AND DATAFILES.

KEEP DATAFILES

When you specify INCLUDING CONTENTS, the KEEP DATAFILES clause lets you instruct the database to leave untouched the associated operating system files, including Oracle-managed files. You must specify this clause if you are using Oracle-managed files and you do not want the associated operating system files removed by the INCLUDING CONTENTS clause.

CASCADE CONSTRAINTS

Specify CASCADE CONSTRAINTS to drop all referential integrity constraints from tables outside tablespace that refer to primary and unique keys of tables inside tablespace. If you omit this clause and such referential integrity constraints exist, then Oracle Database returns an error and does not drop the tablespace.

Examples

Dropping a Tablespace: Example The following statement drops the tbs_01 tablespace and drops all referential integrity constraints that refer to primary and unique keys inside tbs_01:

DROP TABLESPACE tbs_01 
    INCLUDING CONTENTS 
        CASCADE CONSTRAINTS; 

Deleting Operating System Files: Example The following example drops the tbs_02 tablespace and deletes all associated operating system datafiles:

DROP TABLESPACE tbs_02
   INCLUDING CONTENTS AND DATAFILES;