Josh Berkus <josh(at)agliodbs(dot)com> writes:
>> Yeah, this has been discussed before; I think it's even in the TODO
>> list.
> I couldn't find it. At least, not under data types, and also not with
> the keyword "typemod". Anyone see it?
It's the last item under ALTER:
* Don't require table rewrite on ALTER TABLE ... ALTER COLUMN TYPE, when the old and new data types are binary compatible
http://archives.postgresql.org/message-id/200903040137.n241bAUV035002@wwwmaster.postgresql.org
http://archives.postgresql.org/pgsql-patches/2006-10/msg00154.php
regards, tom lane