Thread: Document SQL functions behavior regarding custom/generic plan

Hi,

In [1], we discussed adding some lines regarding the fact that SQL
functions always use generic plan. Here is the suggested patch. I've
tested on V17 and V12. It does not concern V18.

Regards,
Renan

[1] https://www.postgresql.org/message-id/CAApHDvp3EDrVhGjmb21bceJ5-Y7iXKOn2UGG3-ngp_9ob_mpLw%40mail.gmail.com