"Karen Hill" <karen_hill22@yahoo.com> writes:
> I did a quick google and someone mentioned that input and output
> functions need to be written in C. Is that still the case?
Yeah, pretty much. The main problem is that such functions need to deal
with whatever physical on-disk format you've chosen for the datatype,
and most of our PLs don't offer bit-level memory access.
If C functions seem like more work than you want to go to for this
problem, I concur with using a domain over text with a regex check
constraint ...
regards, tom lane