Re: Difference for Binary format vs Text format for client-server communication

On 2020-07-16 18:52, Andy Fan wrote:
> The reason I ask this is because I have a task to make numeric output
> similar to oracle.
>
> Oracle:
>
> SQL> select 2 / 1.0 from dual;
>
>      2/1.0
> ----------
>          2
>
> PG:
>
> postgres=# select  2 / 1.0;
>       ?column?
> --------------------
>  2.0000000000000000
> (1 row)
>
> If the user uses text format, I can just hack some numeric_out function,
> but if they
> use binary format,  looks I have to change the driver they used for it.
> Am I
> understand it correctly?

I think what you should be looking at is why the numeric division
function produces that scale and possibly make changes there. By the
time the type's output or send function is invoked, that's already
decided. The output/send functions are not the place to make scale or
other semantic adjustments.

--
Peter Eisentraut http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services