I wrote:
> It's not so good with two-row windows though:
Actually, carrying that example a bit further makes the point even more
forcefully:
Table correct sum of negative-transition this + next value result 1e20
1e20 1e20 + 1 = 1e20 1 1 1e20 - 1e20 + 0 = 0 0 0
0 - 1 + 0 = -1 0 1 -1 - 0 + 1 = 0 1
Those last few answers are completely corrupt.
regards, tom lane