Function format_real 

pub fn format_real(x: f32) -> String

v7.38 (read01, T-float4) — PG float4out: the f32 shortest round-trip, in fixed-point for decimal exponents in -4..=5 and scientific otherwise (a tighter window than float8’s -4..=14, so 12345678::real = 1.2345678e+07 while 12345678::float8 stays 12345678).