Hi,
> I only add below:
>
> Datum fake_dinstance2(PG_FUNCTION_ARGS)
> {
> PG_RETURN_INT16(0);
> }
> in src/backend/utils/adt/int8.c, and the I run “make install”,
> But I can’t find the fake_distance2 in src/backend/utils/fmgrtab.c which is
> generated by src/backend/utils/Gen_fmgrtab.pl. What else do I need to add?
If the goal is to add a function that can be executed by a user (e.g.
via psql) you have to add it to pg_proc.dat, or alternatively (and
often better) add a corresponding extension to /contrib/. You can find
a complete example here [1] for instance, see v4-0001 patch and the
function pg_get_relation_publishing_info(). Make sure it has a proper
volatility [2]. The patch [3] shows how to add an extension.
[1]: https://postgr.es/m/CAAWbhmjcnoV7Xu6LHr_hxqWmVtehv404bvDye%2BQZcUDSg8NSKw%40mail.gmail.com
[2]: https://www.postgresql.org/docs/current/xfunc-volatility.html
[3]: https://postgr.es/m/CAJ7c6TMSat6qjPrrrK0tRTgZsdXwFAbkDn5gjeDtFnUFrjZX-g%40mail.gmail.com
--
Best regards,
Aleksander Alekseev