Problem with Postgres ALTER TABLE

Question

I have one problem with the ALTER TABLE in postgre. I want to change size of the varchar column. When I try to do this, It says that the view is dependent on that column. I can\

Answer 1

If you don't need to change the type of the field, but just the size of it, this approach should work:

Starting with these tables:

CREATE TABLE foo (id integer primary key, names varchar(10));
CREATE VIEW voo AS (SELECT id, names FROM foo);

\d foo and \d voo both show the length as 10:

id     | integer               | not null
names  | character varying(10) | 

Now change the lengths to 20 in the pg_attribute table:

UPDATE pg_attribute SET atttypmod = 20+4
WHERE attrelid IN ('foo'::regclass, 'voo'::regclass)
AND attname = 'names';

(note: the 20+4 is some crazy postgresql legacy thing, the +4 is compulsory.)

Now \d foo shows:

id     | integer               | not null
names  | character varying(20) | 

Bonus: that was waaay faster than doing:

ALTER TABLE foo ALTER COLUMN names TYPE varchar(20);

Technically you can change the size of the table column without changing the size of the view column, but no guarantees on what side effects that will have; it's probably best to change them both at once.

source and fuller explanation: http://sniptools.com/databases/resize-a-column-in-a-postgresql-table-without-changing-data