In practice, it is often the case that some user will change the data and not approve or withdraw the changes and thus block the resource. The same problem occurs with “suspend the software using the database in the middle of the transaction …

The commands of other users who want to change the same data will be waiting for a picture of the lock (while the user left or the system that put the lock has suspended). We can see who and what blocks us this way: select sid, serial #, lmode, l.request, status, osuser, machine, terminal, program, schemaname, o.name from v $ lock l join obj $ o on .id1 = o.obj #) v $ session s on (s.sid = l.sid); If we need to kill a session that blocks the resource: alter system kill session ‘sid, serial’;