DBA Tips Archive for Oracle
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by Michael New, MichaelNew@earthlink.net, Gradation LLC
In many database configurations, the DBA will choose to allow their temporary tablespace (actually the tempfile(s) for the temporary tablespace) to autoextend. A runaway query or sort can easily chew up valuable space on the disk as the tempfiles(s) extends to accommodate the request for space. If the increase in size of the temporary tablespace (the tempfiles) gets exceedingly large because of a particular anomaly, the DBA will often want to resize the temporary tablespace to a more reasonable size in order to reclaim that extra space. The obvious action would be to resize the tempfiles using the following statement:
Ouch. You next bounce the database and attempt the same statement only to be greeted with the same error!
Several methods exist to reclaim the used space used for a larger than normal temporary tablespace depending on which release of Oracle you are running. The method that exists for all releases of Oracle is to simply drop and recreate the temporary tablespace back to its original (or another reasonable) size. If you are using Oracle9i or higher, you can apply another method which is to drop the large tempfile (which will drop the tempfile from the data dictionary AND the O/S file system) using the alter database tempfile '<tempfile name>' drop including datafiles; command.
Each method is explained below.
Keep in mind that the procedures documented here for dropping and recreating your temporary tablespace should be performed during off hours with no users logged on performing work.
If you are working with a temporary tablespace in Oracle8i or a temporary tablespace in Oracle9i that is NOT the default temporary tablespace for the database, this process is straight forward. Simply drop and recreate the temporary tablespace:
The procedures above document how to drop a temporary tablespace that is not the default temporary tablespace for the database. You will know fairly quickly if the tablespace is a default temporary tablespace when you are greeted with the following exception:
In cases where the temporary tablespace you want to resize (using the drop/recreate method) is the default temporary tablespace for the database, you have several more steps to perform, all documented below. The first step you need to perform is create another temporary tablespace (lets call it TEMP2). The next step would be to remove the temporary tablespace you want to resize from being the default temporary tablespace (in our example, this will be a tablespace named TEMP) by making TEMP2 the default. Drop / recreate the TEMP tablespace to the size you want. Finally, make the newly created TEMP tablespace your default temporary tablespace for the database and drop the TEMP2 tablespace. A full example session is provided below:
If you are using Oracle9i or higher, another method exists that allows you to simply drop a tempfile. As with the above method, this should be performed during off hours with no users logged on performing work.
The first step is to obtain the name of the tempfile to drop. For this example, my temporary tablespace name is TEMP and the name of the tempfile is /u02/oradata/TESTDB/temp2_01.dbf:
The normal size of my temporary tablespace is 512MB which has always been more than adequate for this environment. A bad query, however, increased the size of this tablespace (my tempfile) to over 13GB and I would like to reclaim that space. In the example below, I simply drop and recreate the tempfile:
Jeffrey Hunter is an Oracle Certified Professional, Java Development Certified Professional, Author, and an Oracle ACE. Jeff currently works as a Senior Database Administrator for The DBA Zone, Inc. located in Pittsburgh, Pennsylvania. His work includes advanced performance tuning, Java and PL/SQL programming, developing high availability solutions, capacity planning, database security, and physical / logical database design in a UNIX / Linux server environment. Jeff's other interests include mathematical encryption theory, tutoring advanced mathematics, programming language processors (compilers and interpreters) in Java and C, LDAP, writing web-based database administration tools, and of course Linux. He has been a Sr. Database Administrator and Software Engineer for over 20 years and maintains his own website site at: http://www.iDevelopment.info. Jeff graduated from Stanislaus State University in Turlock, California, with a Bachelor's degree in Computer Science and Mathematics.
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Last modified on
Wednesday, 28-Dec-2011 13:47:10 EST
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