save! silently fails

I'm undecided if this is a bug in ActiveRecord or a hole in the documentation, but I'm certain that it is one or the other. Consider:

irb(main):059:0> obs = Observation.get_observations() ; obs.size
=> 320
irb(main):060:0> obs[0].save!
=> true
irb(main):061:0> Observation.count
=> 0

Note that save! returns without writing anything to the observations table and without any error or warning. Before you conclude that this is an ActiveRecord bug, you should know that get_observations() is a wrapper for find_by_sql():

def Observation.get_observations()
  Observation.find_by_sql(@massive_sql_query_string)
end

Though the AR documentation offers caveats for records generated by find_by_sql(), it makes no mention of this (mis)behavior.

Whether or not you believe this is an AR bug, "save! silently fails" is unexpected and can't be anticipated by reading the documentation alone. I'd suggest that either the code get changed, or the documentation be augmented to warn users about this unexpected consequence of using find_by_sql().

Environment:

bash$ rake about
(in /Users/ff/Developer/dev)
About your application's environment
Ruby version              1.9.2 (x86_64-darwin10.4.0)
RubyGems version          1.3.7
Rack version              1.2
Rails version             3.0.0.rc
Active Record version     3.0.0.rc
Action Pack version       3.0.0.rc
Active Resource version   3.0.0.rc
Action Mailer version     3.0.0.rc
Active Support version    3.0.0.rc
Application root          /Users/ff/Developer/bd
Environment               development