untrusted languages and non-global superusers?

I'm using plphpu and I'd like to allow the regular
database user to use it, but since it's "untrusted" it
requires users to be superusers. If I have to do this,
I don't want the user to be a superuser for all
databases. Is it possible to grant superuser status to
a user for a specific database? All I'm familiar with
is "alter user joe createuser." Or is there a better
way of handling this language and permission issue?
(The function uses mail(), so IIRC that necessitates
using plphpu).

Thanks,
CSN

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