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Oracle
Enterprise Manager Graphical Explain Plan
To execute a data manipulation language (DML)
statement, Oracle needs to perform a number of steps, such
as retrieving rows of data from the database or preparing
them in some way for issuing the statement. The combination
of steps Oracle uses to execute a statement is called an execution
plan. An execution plan includes access methods for each table
that the statement accesses and the ordering of tables (the
join order). The explain plan displays execution plans chosen
by the Oracle optimizer and helps you to understand the optimizer
decisions. Most users do not need to understand a SQL
statement at this level of detail. However, database
administrators and application developers find this information
useful for identifying performance bottlenecks and diagnosing
and tuning high impact SQL.
Oracle Performance Manager and Oracle SQL
Analyze automatically create and display explain plans for
selected SQL. Understanding SQL operations is significantly
easier with Enterprise Manager's Graphical SQL Explain Plan
which presents a graphical diagram of a SQL statement's operations
and their relationship and cost. The graphical explain
plan allows the viewer to easily grasp the type and flow of
operations for the SQL statement, as shown below.
The new format is easy to navigate and understand,
particularly for large explain plans where you can use the
graphical explain plan's zoom in and out capability.
Costly steps in a SQL plan are highlighted so you can immediately
investigate the bottlenecks in the statement. A SQL
Explain Report can also be generated from the new explain
plan. This HTML report provides a tabular presentation
of the explain plan with links to a sequentially ordered list
of step descriptions, making explain plan navigation even
easier. The graphical explain plan can be used as a
drill-down from the Performance Manager charts wherever SQL
is presented (i.e., TopSQL and TopSessions charts).
For more details on the Graphical Explain
Plan see our online
demo.
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Oracle9i
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