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Tablespace Types
There are three types of tablespaces:
■ Permanent
You use permanent tablespaces to store your user and application data. Oracle
Database uses permanent tablespaces to store permanent data, such as system
data. Each user is assigned a default permanent tablespace.
■ Undo
TEMP This tablespace stores temporary data generated when processing SQL
statements. For example, this tablespace would be used for query sorting.
Every database should have a temporary tablespace that is assigned to users
as their temporary tablespace. In the preconfigured database, the TEMP
tablespace is specified as the default temporary tablespace. If no temporary
tablespace is specified when a user account is created, then Oracle Database
assigns this tablespace to the user.
UNDOTBS1 This is the undo tablespace used by the database to store undo information.
See "Managing Undo Data" on page 6-18 to understand how an Oracle
database uses the undo tablespace. Every database must have an undo
tablespace.
USERS This tablespace is used to store permanent user objects and data. Similar to the
TEMP tablespace, every database should have a tablespace for permanent user
data that is assigned to users. Otherwise, user objects will be created in the
SYSTEM tablespace, which is not good practice. In the preconfigured database,
USERS is designated as the default tablespace for all new users.
See Also:
■ "Viewing Tablespace and Data File Information" on page 6-12
■ "Creating a Tablespace" on page 6-12
■ "Modifying a Tablespace" on page 6-14
■ Oracle Database Concepts
Table 6-1 (Cont.) Tablespaces and Descriptions
Tablespace Description
About Database Storage Structures
6-8 Oracle Database 2 Day DBA
A database running in automatic undo management mode transparently creates
and manages undo data in the undo tablespace. Oracle Database uses undo data
to roll back transactions, to provide read consistency, to help with database
recovery, and to enable features such as Oracle Flashback Query. A database
instance can have only one active undo tablespace.
■ Temporary
Temporary tablespaces are used for storing temporary data, as would be created
when SQL statements perform sort operations. An Oracle database gets a
temporary tablespace when the database is created. You would create another
temporary tablespace if you were creating a temporary tablespace group. Under
typical circumstances, you do not have to create additional temporary tablespaces.
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