Undocumented stuff is always very interesting, although there is of course a reason why it is undocumented… Event settings are more or less in this category. They are often used by Oracle Support in their quest to do a good job solving our problems.
Sometimes events disable or enable features. Sometimes they trace internal processes. The later can be very helpful like setting the infamous “10046” event. I noticed some event settings that can be helpful while using XMLDB or the Protocol Server.
Here a small overview of some events that are in the manuals or mentioned during discussions on the OTN XMLDB Forum… Be careful while “playing” with these events. Some are mentioned in the XMLDB Developers Guide and not an big issue, others can cause very strange results or abnormal behavior.
So be advised…