Laurenz Albe <laurenz.albe@cybertec.at> writes: > On Sat, 2022-12-03 at 08:54 +0000, PG Doc comments form wrote: >> I am thinking that the value of the ROUND function with NUMERIC as an >> argument is rounded off, not rounded away from zero.
> It is rounded away from zero, since 43 is farther away from 0 than 42.5. > This may be a language problem.
Perhaps, since I don't see anything wrong with that text either. (Of course, it's moderately likely that I wrote that text, or at least copy-edited it at some point ;-). Don't remember.)
The point is that for 42.5, or anything-point-5, the basic "round to nearest integer" rule is insufficient because 42 and 43 are equally near. We need a tie-breaking rule, and for numeric that rule has historically been to round to the larger absolute value (or "away from zero", as the text puts it to avoid two-dollar terminology). Sadly, that is not what IEEE has established as best practice for floating-point rounding, so round(float8) acts differently.