First, I noticed that there's a significant unanswered issue from Andrew Gierth about this using a completely different mechanism, namely an implicit window function. I see that Robert was concerned about the performance of Andrew's proposed approach, but I don't see any reply from Surafel on the whole issue.
i don't know much about window function implementation but am sure teaching window
function about limit and implementing limit variant on top of it will not be much simpler
and performant than the current implementation. i also think more appropriate place to
include limit variant is limitNode not other place which can case redundancy and
