and now it works! I think they should add casting to 'bytea' directly,
such workarounds shouldn't be necessary.
Casting to bytea and counting the bytes is just as hackey, IMO. If this use-case wants to be officially supported the type itself should define what "length/size" means and a function should be provided to extract that value. I have the impression that the content length is already part of the stored data so really only the function would be needed. I haven't given it that much thought, and zero present research, so I may be mis-remembering old threads.
David J.