> I think what I actually need is a character set without any blank
> characters. My application is trying to use arbitrary binary strings
> as keys, so whenever there is a blank character in the character set
> there will be two different binary strings that are treated as the
> same in indexes (i.e. PK constraint violation). Is there something
> like that?

You may try to avoid keys with blanks at rightmost position.
Or choose key representation which have not used blanks at all.

Regards,
Vlad