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Donald K. Burleson

Oracle Tips  

Oracle tablespaces

* The SYSTEM tablespace, if you split out the tool tables, should only require 300 to 400 MB of disk space, this has increased dramatically due to increased Java and other stored procedures in the Oracle system.

* The TOOLS tablespace will depend entirely on the amount of development you expect. At one site with 16 applications being developed, nearly 90 MB were required for the TOOLS tables.

* The ROLLBACK tablespace will again be driven by the number and size of rollback segments you require. The number and size of rollback segments is driven by the number of transactions per rollback segment, the number of users, and the maximum size of nonbatch transactions. With Oracle8i and Oracle, you can create a large rollback segment and leave it offline until it is needed for a large transaction, and then use the SET TRANSACTION USE ROLLBACK SEGMENT command to utilize it after bringing it online. The number of rollback segments is driven by the number of expected transactions and can be estimated by the equation:


* The number of transactions will be driven by the number of users and types of database operations they will be doing. In fact, if the Oracle kernel sees a violation of the above formula, it will bring online any available public rollback segments. In Oracle you should also consider if you wish to use the UNDO tablespace, which takes the place of the rollback segments if it is configured. By default Oracle sizes the UNDOTBS at 200 megabytes.

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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