Considering adding a serial counter to bugs_activity

[David Marshall]

I have a requirement for a special-use Bugzilla to provide a complete record
of activity since some earlier point.  It would be OK if this included
overlapping events that might be an artifact of using timestamps, but we'd
prefer to avoid overlap, of course.

My first thought is to add an activity_id to table bugs_activity which would
essentially be a transaction counter.  An external web service client would
request details about activity that have occurred since event #231234, for
instance.

This almost certainly implies including the creation of
bugs/attachments/comments as entries in bugs_activity.

Any initial thoughts about this?