Oracle RAC Scans Test
Full table scans on a database instance can degrade the performance of the database. This test monitors the extent of full table scans happening on each database in the Oracle RAC.
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 the Oracle RAC as desired Component type, set Performance as the Test type, choose the 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.
Target of the test : Oracle Cluster
Agent deploying the test : An internal agent
Outputs of the test : One set of results for each database on an Oracle cluster.
|
Measurement | Description | Measurement Unit | Interpretation |
---|---|---|---|
Percent long table scans: |
Indicates the percentage of long table scans happening on this database.
|
Percent |
This measure will not be reported for the Summary descriptor. Ideally, this value should be lower than 10%. If more than 20% of scans are happening on long tables, the database/accesses to the database may need to be tuned. Full table scans may happen due to several reasons. For instance, the indexes of a table may not be used properly in queries. By tuning the queries, the full table scans can be reduced and the database performance significantly improved. |
Long table scans: |
Indicates the number of long table scans that happened on each database in this Oracle RAC during the last measurement period. |
Number |
|
Short table scans: |
Indicates the number of short table scans that happened on each database in this Oracle RAC during the last measurement period. |
Number |
|
Full table scans |
Indicates the number of full table scans that happened on the database instance during the last measurement period. |
Number |
Full table scans may happen due to several reasons. For instance, the indexes of a table may not be used properly in queries. By tuning the queries, the full table scans can be reduced and the database performance significantly improved. The detailed diagnosis of this measure provides details of the SQL ID, Hash Value, Address, SQL Query that is used to perform this scan, the number of times the Executions were performed, etc. |