Re: Type scale returned by PQfmod() 65531 for time/timestamp output parameter?

On 02/21/2018 07:36 PM, Tom Lane wrote:
> Sebastien FLAESCH <sf(at)4js(dot)com> writes:
>> On 02/20/2018 03:39 PM, Tom Lane wrote:
>>> Like I said before, it's datatype-specific and you need to look at the
>>> typmodin/typmodout support functions for each type to see what they do.
>
>> Are you suggesting me to dig into the PostgreSQL server sources / internals?
>
> Yup.
>
>> Any starting point I should look at?
>
> regression=# select distinct typmodout from pg_type where typmodout != 0;
> typmodout
> ----------------------
> intervaltypmodout
> timestamptypmodout
> timestamptztypmodout
> timetypmodout
> timetztypmodout
> bpchartypmodout
> varchartypmodout
> numerictypmodout
> bittypmodout
> varbittypmodout
> (10 rows)
>
> I think all of those are under src/backend/utils/adt/ in the sources.
> Briefly their charter is to produce the textual representation of a
> typmod value for the data type, or an empty string if there's no typmod
> constraint. Although in principle code outside the datatype shouldn't
> assume anything at all about the encoding of typmod, there's a widespread
> assumption that all negative values (not just -1) mean "no constraint".
>
> regards, tom lane
>

OK Thanks!
Seb