Re: delete column

At 04:58 PM 4/26/02 -0400, Bruce Momjian wrote:
>Hillensbeck, Preston wrote:
> > There isn't a DROP COLUMN function yet, but you can do this...
> >
> > SELECT ... -- select all columns but the one you want to remove
> > INTO TABLE new_table
> > FROM old_table;
> > DROP TABLE old_table;
> > ALTER TABLE new_table RENAME TO old_table;
> >
> > This is straight out of Bruce Momjian's book, so you can give him
> credit for
> > this :)
>
>This is from the FAQ, which appears in my book.  I think I wrote that
>too, or at least with help from others.  Wish we had a cleaner way, but
>right now, that is all we have.

The following variant makes use of Postgresql's advantages:

BEGIN;
create new_table ... -- the way you want it to be
lock table old_table;
SELECT ... -- select all columns but the one you want to remove
INTO TABLE new_table
FROM old_table;
DROP TABLE old_table;
ALTER TABLE new_table RENAME TO old_table;
COMMIT;

I did something similar on a production server (after backing up just in
case and testing on a test db) and it worked well. So 3 cheers for
rollback/commits of drop table :).

Got to be careful to get any sequences right tho (grrr!).

Link.