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Oracle: Temporary Tablespace

A temporary tablespace stores objects only for the duration of a session such as
A single temporary tablespace named TEMP is created along with the creation of a database.
When adding more temporary tablespaces, Oracle recommends to create them locally managed with uniform extent sizes of 1MB.
It's not possible to create database objects in a temporary tablespace (however, the column name tablespace_name in dba_private_temp_tables seems to indicate that data stored in a private temporary table may be stored in a temporary tablespace).

Shrinking the tablespace

Temporary tablespaces can be shrunk: 
alter tablespace temp shrink space;
alter tablespace temp shrink space                                       keep 500 m;
alter tablespace temp shrink tempfile '/opt/oracle/oradata/…/temp01.dbf' keep 500 m;

Determine a database's default temporary tablespace

select property_value from database_properties where property_name = 'DEFAULT_TEMP_TABLESPACE';

Tablespace groups

A tablespace group allows to use multiple temporary tablespaces for operations that require large amounts of temporary space.

See also

dba_temp_files, v$tempfile
MOS Note 1498442.1

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