Re: [COMMITTERS] pgsql: Remove arbitrary ALTER TABLE .. ADD COLUMN restriction.

Robert Haas <robertmhaas@gmail.com> writes:
> Yeah, I wasn't aware of that.  I'll go revert, but I think I'll also
> add a big fat comment, because this is entirely non-obvious,

What I think would actually be helpful would be to improve the error
message.  I'm not sure if it's practical to pass down the specific
reason(s) why we need to throw error, but if not, we could consider a
wishy-washy HINT along the lines of "This could be because of X, Y,
or Z".
        regards, tom lane