Hi again,
> So all in all, -1. [...]
Here is something I would like to add:
1. As far as I know, "all the rest of DBMS have this" was never a good argument in the PostgreSQL community. Generally, using it will turn people against you.
2. I recall there was a proposal of making the SQL syntax itself extendable. To my knowledge, this is still a wanted feature [1]. In theory, that would allow you to implement the feature you want in an extension.
[1]:
https://wiki.postgresql.org/wiki/Todo#Exotic_Features--
Best regards,
Aleksander Alekseev