Re: RM VERY STRONG SUGGESTION 4: TRANSITION CONSTRAINTS
Date: Fri, 3 Sep 2010 06:41:14 -0700 (PDT)
Message-ID: <a65d540c-26e4-4acc-9c06-cab884916cb2_at_u4g2000prn.googlegroups.com>
You may be turning things upside down.
It is crystal clear that in a D (which does not expose internal
details such as ROWID), individual tuples can only be identified using
a (/the) key value. Identifying that individual tuples in two
distinct database states are about the same real-life object, is then
only achievable if the key value hasn't changed.
Trying to overcome this, e.g. by introducing some kind of "objectid"
in the data which is "eternally, once and for all" linked to the tuple
in question has other serious ramifications. For example, I suspect
that UPDATE can no longer be seen as a shorthand for some particular
combination of DELETE-then-INSERT, precisely because of this
additional objectid.
Or "I assume there is some kind of other machinery in place that allows supervisors to do all necessary corrections" ? So the model deliberately does not aim to offer support for _ALL POSSIBLE_ transitions ? Come on. Received on Fri Sep 03 2010 - 15:41:14 CEST