On Mon, Mar 31, 2025 at 1:49 PM Tom Lane <t...@sss.pgh.pa.us> wrote: > Robert Haas <robertmh...@gmail.com> writes: > > But why isn't it just as valuable to have two decimal places for the > > estimate? I theorize that the cases that are really a problem here are > > those where the row count estimate is between 0 and 1 per row, and > > rounding to an integer loses all precision. > > Currently, the planner rounds *all* rowcount estimates to integers > (cf. clamp_row_est()). Maybe it'd be appropriate to rethink that, > but it's not just a matter of changing EXPLAIN's print format.
Oh, right. I've never really understood why we round off to integers, but the fact that we don't allow row counts < 1 feels like something pretty important. My intuition is that it probably helps a lot more than it hurts, too. -- Robert Haas EDB: http://www.enterprisedb.com
