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Donald K. Burleson

Oracle Tips  

Oracle tablespaces

SYSTEM. Contains files owned by the SYS and SYSTEM user.

TOOLS. Contains files usually owned by SYSTEM but that apply to the Oracle developer’s toolset; these files contain base information and details of forms, reports, and menus.

ROLLBACK. Contains the private rollback segments; its size will depend on number of rollback segments and expected transaction size. May also be an Oracle-configured UNDO tablespace, which means you will also have to plan for how long UNDO data should be retained to allow for flashback query.

DEFAULT USER. Tablespace in which users can create and destroy temporary, nonapplication-related tables such as those used in SQL*REPORT for intermediate queries.

TEMPORARY USER. Tablespace for sorts, joins, and other operations that require temporary disk space for intermediate operations. If this tablespace is not available, and default tablespace is not set for each user, these tables will be created and dropped in the SYSTEM tablespace, resulting in fragmentation. Additionally, a poorly designed join or overly ambitious SELECT statement could result in filling the SYSTEM area and halting the database.

UNDOTBS. IN Oracle databases created from default templates in the Database Creation Assistant (DBCA) rollback segments are placed in the UNDO tablespace and are now referred to as UNDO segments. Oracle uses automated management of these UNDO segments by default. This UNDOTBS is used by Oracle to hold UNDO segments.

This is an excerpt by Mike Ault’s book “Oracle Administration & Management”.  If you want more current Oracle tips by Mike Ault, check out his new book “Mike Ault’s Oracle Internals Monitoring & Tuning Scripts” or Ault’s Oracle Scripts Download.




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