Fetch Statistics

Open JPA Fetch Statistics Tool monitors persistent field access and determines which fields are never used. This tool
can be used to help tune an application.

Note

• Open JPA Fetch Statistics Tool works with the runtime enhancement.

• Only the persistent fields which satisfy all the following conditions will be tracked by the tool:
  • The field has EAGER fetch mode.
  • The field is not primary key.
  • The field is not defined as a version field.

Download

The latest OpenJPA Tools JAR file can be download from the SNAPSHOT Repository or can be built from the source code in svn by using Maven 2.2.1 and Java SE 6.

Usage

For Regular JVM

• • Configuration

          Append the path of openjpa-fetch-statistics-version-SNAPSHOT.jar file to the classpath prior to lanuching the JVM.

• • Statistics Collecting and Monitoring

          When this tool is configured, it will be active for all persistence units in the JVM. Statistics will be dumped via the
          openjpa.Runtime channel with the INFO level every 10 minutes, or when the JVM terminates. Any EAGER field that is logged
          has not been accessed by an application.

• Configuration removal

          Stop the JVM.
          Remove openjpa-fetch-statistics-version-SNAPSHOT.jar from the classpath.

For Websphere Application Server

Performance Consideration

There will be a large performance impact when running this tooling. It is not supported, nor recommended for production use. This tool should not be used on a production machine.