update view

I'm trying to update a table through a view and have read up on what
constitutes an 'updatable' view. I created a simple test case and cannot
get it to update the table through the view. In the transcript below,
notice that when I update the view, I get 'UPDATE 0' with no error message
or other complaints. What am I missing? Does PostgreSQL not support
updating through views?

-- Brian Haney
brian(at)cybernaut(dot)com

============================ BEGIN SAMPLE ========================

$ psql -f /tmp/viewtest test2
create table peanuts (
name text,
age int4,
height int4,
weight int4);
CREATE
insert into peanuts values ('Charlie Brown', 50, 24, 75);
INSERT 21228 1
insert into peanuts values ('Snoopy', 21, 18, 25);
INSERT 21229 1
insert into peanuts values ('Lucy van Pelt', 50, 27, 65);
INSERT 21230 1
insert into peanuts values ('Linus van Pelt', 50, 24, 75);
INSERT 21231 1
select * from peanuts;
name |age|height|weight
--------------+---+------+------
Charlie Brown | 50| 24| 75
Snoopy | 21| 18| 25
Lucy van Pelt | 50| 27| 65
Linus van Pelt| 50| 24| 75
(4 rows)

create view dogs as select * from peanuts where name = 'Snoopy';
CREATE
select * from dogs;
name |age|height|weight
------+---+------+------
Snoopy| 21| 18| 25
(1 row)

update dogs set age = 145;
UPDATE 0
select * from dogs;
name |age|height|weight
------+---+------+------
Snoopy| 21| 18| 25
(1 row)

EOF
$