There are a few ways to monitor IMU activity. (Detecting and resolving performance problems are covered in the next section.)

You cannot directly control the memory Oracle allocates to the IMU buffers. However, you can possibly indirectly influence Oracle's IMU memory allocation by altering the shared pool size by changing, for example, the shared_pool_size instance parameter. The current IMU memory allocation can be easily queried, as shown in the following code snippet:

Like many other Oracle statistics, IMU activity is recorded via the system statistics view, v$sysstat and v$sesstat. It's also interesting to watch the change between standard commits and IMU commits. If you see IMU commits increasing, you know IMU is active. The following is an example showing and comparing IMU and user commits.