2.7 Comparing Performance Measurements

SQL Performance Analyzer compares the performance of SQL statements before and after the change and produces a report identifying any changes in execution plans or performance of the SQL statements.

SQL Performance Analyzer measures the impact of system changes both on the overall execution time of the SQL workload and on the response time of every individual SQL statement in the workload. By default, SQL Performance Analyzer uses elapsed time as a metric for comparison. Alternatively, you can choose the metric for comparison from a variety of available SQL run-time statistics, including:

  • CPU time

  • User I/O time

  • Buffer gets

  • Physical I/O

  • Optimizer cost

  • I/O interconnect bytes

  • Any combination of these metrics in the form of an expression

If you chose to generate explain plans only in the SQL trials, then SQL Performance Analyzer will use the optimizer cost stored in the SQL execution plans.

Once the comparison is complete, the resulting data is generated into a SQL Performance Analyzer report that compares the pre-change and post-change SQL performance. The SQL Performance Analyzer report can be viewed as an HTML, text, or active report. Active reports provides in-depth reporting using an interactive user interface that enables you to perform detailed analysis even when disconnected from the database or Oracle Enterprise Manager.

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