The other day, I was obsessing over an alert in Oracle Enterprise Manager Cloud Control 12c Release 4, because the error message was cryptic. In the Incident Manager console, I got the following line for an Oracle Database 12.2 target :
I expected to have some value or an explicit error message. I did not understand why I would get an “ORA-00942: table or view does not exist”. When drilling down on this alert, I noticed it belonged to a Metric Group called “Deferred Transactions” (and of course I had no idea what it was) :
But I still did not understand why I would get such an error (instead of a numeric value for example) and why the Event Type was “Metric Evaluation Error”.