Re: ALTER TYPE recursion to typed tables

On Tue, Nov 2, 2010 at 9:15 AM, Peter Eisentraut <peter_e@gmx.net> wrote:
> I'm working on propagating ALTER TYPE commands to typed tables.  This is
> currently prohibited.  For example, take these regression test cases:
>
> CREATE TYPE test_type2 AS (a int, b text);
> CREATE TABLE test_tbl2 OF test_type2;
> ALTER TYPE test_type2 ADD ATTRIBUTE c text; -- fails
> ALTER TYPE test_type2 ALTER ATTRIBUTE b TYPE varchar; -- fails
> ALTER TYPE test_type2 DROP ATTRIBUTE b; -- fails
> ALTER TYPE test_type2 RENAME ATTRIBUTE b TO bb; -- fails
>
> The actual implementation isn't very difficult, because the ALTER TABLE
> code already knows everything about recursion.
>
> Now I'm wondering what kind of syntax should be used to control this.  I
> think you don't want to automatically propagate such innocent looking
> operations to tables in a potentially data-destroying manner.  The
> natural idea would be RESTRICT/CASCADE.  This is currently only
> associated with DROP operations, but I suppose ADD/ALTER/RENAME
> ATTRIBUTE x ... CASCADE doesn't sound too odd.
>
> Comments, other ideas?

That seems reasonable.  What do you plan to do about this case?

CREATE TYPE test_type AS (a int, b text);
CREATE TABLE test_tbl (x test_type);
ALTER TYPE test_type ADD ATTRIBUTE c text;

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company