Re: Float/Double cast to int

Feng Tian <ftian@vitessedata.com> writes:
> Here is a query, server was built witch GCC on Linux, AMD64.

> ftian=# select 1.5::int, 1.5::double precision::int, 314.5::int,
> 314.5::double precision::int;
>  int4 | int4 | int4 | int4
> ------+------+------+------
>     2 |    2 |  315 |  314
> (1 row)

> I believe this is because rint is broken -- can some expert on IEEE754
> please help confirm that this is a bug?

rint() is doing what the IEEE spec says, ie round to nearest even.
Your third expression is doing numeric-to-int, and that code doesn't
obey the IEEE spec.  We've had discussions (not too long ago) about
making these behaviors more consistent, but people seem to be too
afraid of backwards-compatibility problems if we change it.

                        regards, tom lane