Stephan Szabo <sszabo(at)megazone23(dot)bigpanda(dot)com> writes:
> If you were using varchar, this would be fine. With char, you have
> issues with the padding spaces if you ever convert them to text
> (for example using lower or upper).
But you could do
update foo set mycol = mycol || '';
after tweaking the atttypmod as Stephan illustrates. That should force
all the values to the correct length. (The dummy concatenation is just
to prevent the system from optimizing away the length coercion step.)
regards, tom lane