I was able to break it just fine. Can you test something similar?
Note that if your procedure is waiting for a lock, of if it is performing SQL statements with internal sorts, it may not break or may not break immediately.
If your update is waiting for a lock, the break will not have any effect. You could kill the session of course by executing an ALTER SYSTEM KILL SESSION statement from another privileged session.
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Marco Kalter
Allround Automations