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This section includes the following topics:
- About the SQL tab
- How the SQL tab is structured
- About the Related SQL selector
- About the View tabs
- About Tuning Actions
- How the SQL tab can help you identify performance problems
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The process of explaining statements is a prerequisite for tuning. The explain process is designed to clarify the access path chosen for a statement and translate it into a visual medium. The SQL tab helps you identify bottlenecks and guides you through the steps required to tune SQL statements.
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See “About the Dashboard tab” on page 43, “About the Current tab” on page 51, “About the Activity tab” on page 61, and “About the Objects tab” on page 87.*
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The SQL tab lets you analyze execution plans and explain results so that you can tune statements and achieve optimal results.
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- Related SQL selector
- View tabs
- Tuning Action buttons
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The Related SQL selector appears only in the Plan view if a statement has a related SQL. The first time you visit the SQL tab, it will not be visible. It lets you choose one of the alternative statements that are associated with an original statement. An original statement is one captured by the Collector, imported, or entered manually. Full details on the related SQL are held in the Related SQL view.
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- When you edit a statement and save an alternative. see “Editing an existing statement” on page 154.
- When you click New Alternatives in the Related SQL view, and Precise for Oracle creates an alternative SQL for you. See “Generating new alternatives” on page 156.
- When an index recommendation is made in the What-If tab and you click Compare to switch to the SQL tab, in which case a copy of the statement is saved along with its new virtual index and execution plan. See “About the What-If tab” on page 159.
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The SQL tab divides the information on the selected statement into different views. Each view has a different layout and presents different information.
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The Text tab displays the SQL text for each alternative.
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The Tuning Actions icon lets you perform additional tuning functions. These action options are accessed by clicking on their related button or by accessing them through the Actions menu.
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To generate a new alternative
1 In , in the Run Alternatives view, click Actions>Generate Alternative.
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After identifying a problematic statement that is slowing down the response time of a specific application, the first step in tuning the statement is to understand the access path that Oracle chose for the statement. The explain procedure is designed to clarify the access path chosen for a statement and translate it into a visual medium. Therefore, you can easily see whether the optimizer chose the proper execution plan. For example, you can see whether the optimizer performed an index seek as expected. In addition, you can see schema changes related to the statement's objects and compare these changes with previous access plans and In Oracle over time data for the selected statement to understand how the changes affected a statement's performance. You can also compare previous access plans and locate the steps that have been changed.
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