changing varchar limits

On Thu, 1 Aug 2002, Jeff Davis wrote:

What's the easiest way to change the allowable length of a varchar attribute?

I looked in pg_attribute and noticed that the allowable length of the varchar
(+4 bytes for the actual length, presumably) was the atttypemod attribute of
the pg_attribute relation. Is it safe to change that? I would of course need
to be a superuser.

That should be safe to change. If you're lowering it, you should make
sure the data fits.

Stephan Szabo wrote:

On Thu, 1 Aug 2002, Jeff Davis wrote:

What's the easiest way to change the allowable length of a varchar attribute?

I looked in pg_attribute and noticed that the allowable length of the varchar
(+4 bytes for the actual length, presumably) was the atttypemod attribute of
the pg_attribute relation. Is it safe to change that? I would of course need
to be a superuser.

That should be safe to change. If you're lowering it, you should make
sure the data fits.

To easily change a column from nullable to not-nullable, is flipping the
proper attribute all that's required? Just asking, cause it would be
very useful until there's an ALTER TABLE equivalent (in 7.3?).

Thanks,
Kevin

Kevin Brannen <kevinb@nurseamerica.net> writes:

To easily change a column from nullable to not-nullable, is flipping the
proper attribute all that's required? Just asking, cause it would be
very useful until there's an ALTER TABLE equivalent (in 7.3?).

Sure, just flip the bit (though if you're going to the not-nullable
state, it's your responsibility to make sure the existing data is in
fact not null). This is basically what the 7.3 implementation does.

regards, tom lane