When you make modifications to an existing enterprise application that requires software or hardware upgrades, how do you ensure that changes from the test environment will run smoothly in the production environment? If you are using the latest versions of Oracle Database 10g and 11g, you have solved more than half the problem. Oracle Database 11g has added a new feature called Database Replay for real-world testing of system modifications as in production environment.
The Database Replay feature can capture a workload from the production environment and replay it in test environment with similar timing and characteristics as original workload in production. You can check on results, system contention points, regression analysis, and performance impact on test systems without actually making those changes in the production environment.
We can use Database Replay to measure the effect of database upgrades, schema changes, patches, and code changes. Major upgrade efforts or configuration changes involving operating system patches and upgrades, Real Application Clusters and ASM (Automatic Storage Management), storage, hardware or network changes can all be tested out using Database Replay feature.
Database Replay feature can be used for workload capture on Oracle Database 10g Release 2 (10.2.0.4) and newer versions and releases. But, the workload replay feature is supported only in Oracle Database 11g Release 1 and newer releases. The workload can be captured into capture files on the production system and then copied over to test or development systems. The capture files are platform independent and will contain all information about client requests and transaction details. On development or test systems, replay these capture files to mimic testing on production environment. This will recreate all captured client system requests with consistent timing and transaction dependencies of the production system.
For recreating all client requests on the test environment, Database Replay uses a replay client program during workload capture. We may need to use more than one replay clients to properly mimic the entire workload. Once we replay the workload, use the inbuilt reporting tools for detailed analysis of workload capture and database replay. In the summary report, we will get information about errors if any with workload capture and replay. We also get comparison of statistics like average active session, database time, user calls etc. You can also use the Automatic Workload Repository (AWR) reports for detailed comparison of performance statistics.
Using Database Replay in Oracle Database 11g, organizations can test system changes quickly with less down time and adopt newer technologies with lower risk and greater confidence.