Simply killing the Oracle process from the unix command line seems to work, and I suspect it is safe, but does anyone know for sure if it will always be safe? It is certainly simpler, so is there any reason to prefer the more complicated "alter system kill session ..." method?
One of the background processes (smon?) looks out for abnormally terminated processes and then cleans up the mess left behind (locks, allocated blocks with half-filled transaction data, etc). Doing the "alter system" stuff lets oracle clean that stuff up directly (presumably using information associated in the oracle process that's running the session) They're probably equivalent, with the alter sytem taking less time / fewer resources. Plus you never know if there's some race condition lurking in the oracle software that'll get triggered with the oracle process going away suddently.
personally I prefer to alter system to slaughter first, and then resort to the kill program if that doesn't work / things are in dire straits.
