Paul Guo <paul...@gmail.com> writes: > Postgres seems to always optimize ORDER BY + LIMIT as top-k sort. > Recently I happened to notice > that in this scenario the output tuple number of the sort node is not > the same as the LIMIT tuple number.
No, it isn't, and your proposed patch is completely misguided.
The cost and rowcount estimates for a plan node are always written
on the assumption that the node is run to completion.
regards, tom lane
