Re: Revoke "drop database" even for superusers?

On Fri, 2012-11-09 at 09:19 -0200, Edson Richter wrote:
> I've a bunch of databases that cannot be dropped in any case.
>
> I was wondering if it is possible to revoke "drop database" permission
> for all users, in order that even superuser, if he wishes to drop a
> database, he will need first to "grant drop database" first.
>
> I know there is already a safety that does not allow dropping databases
> in use - I just want to make even harder.
>

You can also use the hook system to add this feature to PostgreSQL
(without changing PostgreSQL code). With the code available on
https://github.com/gleu/Hooks-in-PostgreSQL/tree/master/examples/deny_drop, you can have a shared library that will take care of denying the drop of a database.

Once compiled and intalled, you need to change the postgresql.conf file
with this new setting:

shared_preload_libraries = 'deny_drop'

After you restart PostgreSQL, it should work like this:

$ psql postgres
psql (9.2.1)
Type "help" for help.

postgres=# create database tryme;
CREATE DATABASE
postgres=# drop database tryme;
ERROR: cannot drop a database!
postgres=# set deny_drop.iknowwhatiamdoing to true;
SET
postgres=# drop database tryme;
DROP DATABASE
postgres=# \q

AFAICT, this code has never been used in production, but it's so simple
I don't think you risk anything using it.

Anyway, it's still better to actually use the user's permissions to deny
him to drop databases. But this little shared library may still be
usefull.

--
Guillaume
http://blog.guillaume.lelarge.info
http://www.dalibo.com