> Before I issue a GRANT to allow select rights on that table to anyone
> who tries, my questions are:
> * Is there any inherent danger in allowing SELECT on that table to
>  normal users?
> * Is there a better way (I looked for a store procedure, such as
>  getlocalnodeid(), but if it exists, I'm not seeing it in the docs)

Can't you define a function that does that query and returns
true/false as necessary, and is declared as SECURITY DEFINER so that
it runs with sufficient privileges?