The plan of an SQL can change, and the change is justified if it doesn’t degrade performance. Changes in the values of bind variables,  change in statistics etc. can change the plan which is often an expected behavior. But now and then you may see a change that degrades performance. Below script compares the plans for  SQL s from […]

Following is a brief account of some serious issues we had with DRM on a 3 node RAC system running 11g R2. We had intermittent spikes that were severe enough to disrupt service. Here is a section from a 10-minute ASH showing DRM related wait “gcs drm freeze in enter server mode.” Our first attempt was to disable DRM by setting _gc_policy_time=0. […]