On one of my production Oracle database 11g Standard Edition I have a lot (a very lot of) indexes. Some of them (majority) are created by the application installer, others are created by me when I identify a request who need some dba work. I'm pretty sure that some of them aren't used at all and I want to identify them.
For that task, I alter all my table & index setting MONITORING status.
After a while (several weeks) I watched about used status :
SELECT index_name, table_name, monitoring, used, start_monitoring, end_monitoring FROM v$object_usage ORDER BY index_name;
I notice that a lot of indexes have now a NOMONITORING status ...
I search to understand what happened and why about this status.
Except the regular
ALTER INDEX index_name NOMONITORING USAGE query, what is likely to change this? Does anyone know a process (a standard Oracle's in-dictionary process) that remove the MONITORING status?