Currently, in FB, when a client (client #1) updates a row (and still
hasn't finished his transaction), then client #2 which tries to update
the same row will be rejected by FB.

Suppose the update by client #1 is increasing the value of a numeric
field by 1 (e.g. 5 becomes 6). And the client #2's udpdate is of the
same operation. In other words, the two updates are non-conflicting.
Both can be applied at whatever order and the effects are the same (I
think the mathematical term is 'commutative'?)

Is there some way that I can convince/make FB allow those two updates?
The goal is not to have client #2's update operation be rejected with a
conflict error.

Or is there any known database that can do something 'smart' like this?

--
dave