Oracle Extents Test
An extent in Oracle is a set of contiguous blocks allocated in Oracle for storage of data. Since this is one of the basic units of allocation, proper management of extents is essential for efficient database performance. The Oracle Extents test helps in identifying objects that are running out of extents and those that are using too many extents.
This test is disabled by default. To enable the test, go to the enable / disable tests page using the menu sequence : Agents -> Tests -> Enable/Disable, pick Oracle Database as the Component type, Performance as the Test type, choose this test from the disabled tests list, and click on the << button to move the test to the ENABLED TESTS list. Finally, click the Update button.
Note:
This test is applicable only for Oracle databases with ‘Dictionary Managed Tablespace’. From Oracle 9i onwards, all tablespaces are ‘Locally Managed Tablespaces’. Therefore, this test is applicable only up to Oracle 8i.
Target of the test : An Oracle 12c server
Agent deploying the test : An internal agent
Outputs of the test : One set of results for every Oracle server.
|
Measurement | Description | Measurement Unit | Interpretation |
---|---|---|---|
Cannot extend objects: |
This measure indicates the number of objects that cannot extend any further by acquiring new extents. |
Number |
This measure indicates the objects have run out of extents. This could be because the objects are either too fragmented or the number of extents allocated to them are too less. Consider modifying the “maxextents” parameter to rectify this. Alternately if fragmentation is the cause then, consider exporting and then dropping and re-importing the object. The detailed diagnosis of the Cannot extend objects measure, if available, provides a complete list of objects that cannot be extended. Once the objects are identified, administrators can then consider increasing the extents allocated to the listed objects. |
Large extent objects: |
This measure indicates the object that exceeds a pre-specified number of extents. The threshold value for the number of extents is configured via the admin user interface. |
Number |
This indicates that the objects are using up more extents than the threshold set. This over-utilization can be due to different types of fragmentation. Consider exporting and then dropping and re-importing the object. Note that the storage parameters set also affects how the extents are allocated. The detailed diagnosis of the Large extent objects measure reveals the list of objects that exceed a pre-specified number of extents. |