Multiple accounting requests crash the server

[Mother]

Hi all,

I am seeing a strange situation. I receive an accounting-stop request 
from a NAS, and FreeRADIUS (1.1.7 against Oracle) updates the 
corresponding radacct record. However, the NAS is not receiving the ack, 
and thus re-sends the stop request. On the second request, FreeRADIUS 
tries to do an update query again, and then, an insert query, with the 
stop message details (i.e. only a stop time, reason idle-timeout, etc.), 
which fails. After the third request from the NAS (and corresponding 
update followed by insert), Oracle throws a unique constraint violation 
error, and the server freezes.

Questions:

1. Why is FreeRADIUS failing to see that this request was already 
acknowledged, i.e. it has been updated on the database, and just sends 
an ACK, rather than trying to insert a new record?

2. Why does FreeRADIUS freeze on an SQL error from Oracle? Should it not 
just log the error and carry on about its business? I am finding my 
server freezing every few days due to these issues, for example, if a 
query takes too long to run, or a trigger fails to execute. Is 
FreeRADIUS against Oracle more fragile than say MySQL?

Cheers,

Mike