Temporary Tablespaces are used to store temporary objects such as sorts, joins, temporary tables, and indexes. The best practices for managing and optimizing Oracle’s Temporary Tablespaces are:
1. Properly sizing the Temporary Tablespace:
The size of the Temporary Tablespace should be determined based on the maximum required sort size. Oracle recommends that the size of the Temporary Tablespace should be two or three times larger than the largest sort operation performed by the database. This avoids the need for the database to extend the Temporary Tablespace frequently, which can cause performance issues.
2. Multiple Temporary Tablespaces:
Having multiple Temporary Tablespaces can significantly reduce contention for the Temporary Tablespace. Therefore, it’s a best practice to create multiple Temporary Tablespaces to spread out the load.
3. Locality considerations:
Oracle recommends creating temporary tablespaces on separate disks from those used for permanent tablespaces. By doing this, it is possible to avoid the situation where temporaries and permanents must share I/O resources.
4. Autoextend:
Set autoextend for the Temporary Tablespace to avoid the need for manual resizing.
5. Monitor the usage:
It’s essential to monitor the usage of Temporary Tablespace regularly. This allows the database administrators to take action before any space issues arise. Oracle provides several views to analyze Temporary Tablespace usage, such as the V$TEMPSPACE_USAGE view.
6. Assure proper space management:
Assure proper space management like optimal size of tempfiles, maxsize of tempfile, correct settings for extend policies, etc. This is important because space is a critical source of contention in creating sort areas.
7. Implement Automatic Management of Temporary Tablespace (AMTT):
Temporary tablespace can be created with the "TEMPFILE" clause indicating "AUTOEXTEND ON NEXT 1m MAXSIZE UNLIMITED". This would enable the Oracle database to automatically manage the space allocated to the temporary tablespace.
Here is an example:
CREATE TEMPORARY TABLESPACE TEMP01
TEMPFILE '/u01/oracle/data/TEMP01.dbf' SIZE 500M
AUTOEXTEND ON NEXT 50M MAXSIZE UNLIMITED
EXTENT MANAGEMENT LOCAL;The above command creates a Temporary Tablespace called TEMP01 with a size of 500MB. The Temporary Tablespace will auto-extend by 50MB whenever space runs out, up to an unlimited size.
In conclusion, efficiently managing and optimizing Oracle’s Temporary Tablespaces is critical for optimal database performance. Properly sizing the Temporary Tablespace based on the maximum required sort size, creating multiple Temporary Tablespaces, monitoring usage regularly, and implementing Automatic Management of Temporary Tablespace (AMTT) are best practices.