After the post-change SQL performance data is built, you can compare the performance data collected in the pre-change SQL trial to the post-change SQL trial by running a comparison analysis using SQL Performance Analyzer. After the comparison analysis is completed, you can generate a report to identify the SQL statements that have improved, remained unchanged, or regressed due to the system change. The SQL Performance Analyzer report calculates two chief impact measurements for the change in performance of each SQL statement:
Impact on workload
This represents the percentage of impact that this change to the SQL statement has on the cumulative execution time of the workload, after accounting for execution frequency. For example, a change that causes a SQL statement's cumulative execution time to improve from 101 seconds to 1 second—where the rest of the workload had a total execution time of 99 seconds before the change—would have a 50% (2x) value for this measurement.
Impact on SQL
This represents the percentage of impact that this change to the SQL statement has on the SQL statement's response time. For example, a change that causes a SQL statement's response time to improve from 10 seconds to 1 second will have a 90% (10x) value for this measurement.
For more information, see "Comparing Performance Measurements".
This chapter describes how to compare and analyze the performance data from the pre-change and post-change SQL trials and contains the following topics:
The primary interface for comparing SQL trials is Oracle Enterprise Manager. If for some reason Oracle Enterprise Manager is unavailable, you can compare SQL trials using the
DBMS_SQLPA PL/SQL package.
Before comparing SQL trials, you need to create a post-change SQL trial, as described in Creating a Post-Change SQL Trial .