The sequence field is not a SQL sequence but a normal one (which should be set by the real alarm producer). 

This a legacy problem. We initially determined to use the three fields   (eventid, sequence, sourcename)  as the primary key of an alarm, but in fact, we found that eventid + sourcename was enough to identify it. So the sequence is not actually used.

Wherever the sequence field is used that need to be removed to avoid confusion and make the code base understandable better.