When you optimize a SQL statement, it is important to consider the scalability of the alternatives SQL Optimizer generates before you implement them in your production database. SQL performance and scalability are two important factors that determine a database application's ability to handle an increase user load. The performance of a SQL statement changes as the number of users increase. Performance problems can arise when you use certain SQL statements under a heavy user load.
Note: This topic focuses on information that may be unfamiliar to you. It does not include all step and field descriptions.
To test for scalability
Select a SQL statement in the Alternatives pane.
Click the arrow beside and select an option.
Review the following for additional information:
Minimum number of virtual users |
Enter the minimum number of virtual users to use for scalability testing. Range: 1 to 1,000,000,000 |
Maximum number of virtual users |
Enter the maximum number of virtual users to use for scalability testing. Range: 1 to 1,000,000,000 |
Step value of virtual users |
Enter the number of virtual users to increase by for each step of scalability testing. Range: 1 to 1,000,000,000 |
Distribution Model |
Select a latency think time distribution model:
|
Duration (milliseconds) |
Enter a duration in milliseconds. Note: How SQL Optimizer uses the value you enter depends on the distribution model selected. |
Execute Each SQL Statement by |
Select one of the following:
|
About Optimizing SQL (SQL Rewrite)
Automatically Optimize SQL Statements
To alter session parameters
Right-click the Alternative Details or SQL Text pane and select Alter Session Parameters.
Tip: You can also alter session parameters for alternatives by right-clicking the alternative in the Alternatives or Plans pane and selecting Alter Session Parameters.
Enter or select a new Oracle session parameter.
Notes:
You must alter session parameters for SQL statements or alternatives individually.
To alter session parameters, you must have access to the SYS.V_$PARAMETER system view.
In an Optimize SQL session (SQL Rewrite or Plan Control), you can execute the original or an alternative SQL statement to retrieve and review the statement's result set.
To retrieve result set
Right-click the selected statement in the Alternatives list (or right-click the SQL text) and select Run Result.
In the Run Result dialog, click . After the script executes, the result set displays in the Result pane of the Run Result dialog.
Tip: Click to copy the SQL statement to execute in another Quest Software product.
To review details for an alternative
Select a SQL statement or index alternative in the Alternatives pane.
Review the details of the alternative in the Execution Plan pane.
Note: You must execute the alternatives before you can review run time statistics.
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