Обсуждение: CREATE/DROP ROLE transactional? GRANT/REVOKE?

> On 06/03/2023 14:19 CET Dominique Devienne <ddevienne@gmail.com> wrote:
>
> Perhaps I missed it in the doc (e.g. [1]), but are DDLs around ROLEs and
> GRANTs transactional?

Have you tried?  DDL is transactional unless stated otherwise (cf. CREATE DATABASE,
CREATE INDEX CONCURRENTLY, CREATE TABLESPACE).

Run the following psql script:

    drop role if exists alice, bob;

    \du

    begin;
    create role alice;
    \du
    rollback;

    \du

    begin;
    create role alice;
    create role bob;
    commit;

    \du

    begin;
    grant alice to bob;
    \du
    rollback;

    \du

    begin;
    drop role alice;
    \du
    rollback;

    \du

Output:

    DROP ROLE
                                       List of roles
     Role name |                         Attributes                         | Member of
    -----------+------------------------------------------------------------+-----------
     postgres  | Superuser, Create role, Create DB, Replication, Bypass RLS | {}

    BEGIN
    CREATE ROLE
                                       List of roles
     Role name |                         Attributes                         | Member of
    -----------+------------------------------------------------------------+-----------
     alice     | Cannot login                                               | {}
     postgres  | Superuser, Create role, Create DB, Replication, Bypass RLS | {}

    ROLLBACK
                                       List of roles
     Role name |                         Attributes                         | Member of
    -----------+------------------------------------------------------------+-----------
     postgres  | Superuser, Create role, Create DB, Replication, Bypass RLS | {}

    BEGIN
    CREATE ROLE
    CREATE ROLE
    COMMIT
                                       List of roles
     Role name |                         Attributes                         | Member of
    -----------+------------------------------------------------------------+-----------
     alice     | Cannot login                                               | {}
     bob       | Cannot login                                               | {}
     postgres  | Superuser, Create role, Create DB, Replication, Bypass RLS | {}

    BEGIN
    GRANT ROLE
                                       List of roles
     Role name |                         Attributes                         | Member of
    -----------+------------------------------------------------------------+-----------
     alice     | Cannot login                                               | {}
     bob       | Cannot login                                               | {alice}
     postgres  | Superuser, Create role, Create DB, Replication, Bypass RLS | {}

    ROLLBACK
                                       List of roles
     Role name |                         Attributes                         | Member of
    -----------+------------------------------------------------------------+-----------
     alice     | Cannot login                                               | {}
     bob       | Cannot login                                               | {}
     postgres  | Superuser, Create role, Create DB, Replication, Bypass RLS | {}

    BEGIN
    DROP ROLE
                                       List of roles
     Role name |                         Attributes                         | Member of
    -----------+------------------------------------------------------------+-----------
     bob       | Cannot login                                               | {}
     postgres  | Superuser, Create role, Create DB, Replication, Bypass RLS | {}

    ROLLBACK
                                       List of roles
     Role name |                         Attributes                         | Member of
    -----------+------------------------------------------------------------+-----------
     alice     | Cannot login                                               | {}
     bob       | Cannot login                                               | {}
     postgres  | Superuser, Create role, Create DB, Replication, Bypass RLS | {}

> Since I'm creating many ROLEs and making many GRANTs, based info I read from
> PostgreSQL itself (in pg_catalog and elsewhere), should everything be in a
> single transaction?

If it should be atomic and the commands are allowed in transactions, then yes,
use transactions.

--
Erik

Dominique Devienne <ddevienne@gmail.com> writes:
> Hi. Perhaps I missed it in the doc (e.g. [1]), but are DDLs around ROLEs
> and GRANTs transactional?

Your expectation is set wrongly.  DDL commands in Postgres are
transactional unless their man page explicitly says they're not.

            regards, tom lane

Dominique Devienne <ddevienne@gmail.com> writes:
> On Mon, Mar 6, 2023 at 4:06 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> DDL commands in Postgres are
>> transactional unless their man page explicitly says they're not.

> Could you point to where in the doc this is stated?

For example, for CREATE DATABASE the first "Note" para in [1] is

    CREATE DATABASE cannot be executed inside a transaction block.

I don't think we are entirely consistent about whether this is
mentioned in "Description" or "Notes", but it's there somewhere.

            regards, tom lane

[1] https://www.postgresql.org/docs/current/sql-createdatabase.html