PostgreSQL 8.0.0rc4
5.6.1 "Adding a Column" says:
Also, you cannot define a default value on a new column. According
to the SQL standard, this would have to fill the new columns in the
existing rows with the default value, which is not implemented yet.
Adding a column with a default appears to be implemented now:
CREATE TABLE foo (label text);
INSERT INTO foo VALUES ('item 1');
INSERT INTO foo VALUES ('item 2');
INSERT INTO foo VALUES ('item 3');
ALTER TABLE foo ADD COLUMN value integer DEFAULT 123;
SELECT * FROM foo;
label | value
--------+-------
item 1 | 123
item 2 | 123
item 3 | 123
(3 rows)
--
Michael Fuhr
http://www.fuhr.org/~mfuhr/