PostgreSQL 权限不继承：数据库 owner ≠ schema owner ≠ table owner

这一点跟SQL Server非常不一样。

SUPERUSER跟SQL Server的sysadmin一样，最高权限。

user和role等同，create user语句默认带有login，而create role默认不带有login属性。

instance level:

--https://www.postgresql.org/docs/18/role-attributes.html

CREATE ROLE name SUPERUSER;

CREATE ROLE name CREATEDB;

CREATE ROLE name CREATEROLE;

CREATE ROLE name REPLICATION LOGIN;

CREATE ROLE name LOGIN;

CREATE ROLE name PASSWORD 'string';

CREATE ROLE name NOINHERIT; ---默认是INHERIT

CREATE ROLE name BYPASSRLS;

CREATE ROLE name CONNECTION LIMIT 'integer'; -- "-1"(the default) means no limit.

-- View all roles and their instance-level privileges
SELECT 
    rolname,
    rolsuper,
    rolinherit,
    rolcreaterole,
    rolcreatedb,
    rolcanlogin,
    rolreplication,
    rolconnlimit,
    rolbypassrls
FROM pg_roles;

--Predefined Roles

--https://www.postgresql.org/docs/18/predefined-roles.html

pg_monitor

pg_read_all_settings

pg_read_all_stats

pg_stat_scan_tables

pg_signal_backend

pg_checkpoint

pg_use_reserved_connections

pg_read_server_files

pg_write_server_files

pg_execute_server_program

pg_database_owner

pg_read_all_data

pg_write_all_data

pg_create_subscription

pg_maintain

pg_signal_autovacuum_worker

--database level

CONNECT

CREATE

TEMPORARY

ALL       

--ALL指的是拥有上面3个权限

GRANT { { CREATE | CONNECT | TEMPORARY | TEMP } [, ...] | ALL [ PRIVILEGES ] }

ON DATABASE database_name [, ...]

TO role_specification [, ...] [ WITH GRANT OPTION ]

[ GRANTED BY role_specification ]

--https://www.postgresql.org/docs/18/functions-info.html

has_database_privilege ( [ user name or oid, ] database text or oid, privilege text ) → boolean

Does user have privilege for database?

Allowable privilege types are CREATE, CONNECT, TEMPORARY, and TEMP (which is equivalent to TEMPORARY).

--默认设置下，任何一个用户都可以连接到新建的数据库，因为默认connect权限是给到public的。
--可以用以下命令收回权限：
revoke connect on database mydb from public;

SELECT 
    datname,
    r.rolname as grantee,
    has_database_privilege(r.rolname, datname, 'CONNECT')  as connect_priv,
    has_database_privilege(r.rolname, datname, 'CREATE')  as create_priv,
    has_database_privilege(r.rolname, datname, 'TEMPORARY') as temp_priv
FROM pg_database d
CROSS JOIN pg_roles r
WHERE --d.datname = 'mydb'    AND 
r.rolname NOT LIKE 'pg_%'
ORDER BY r.rolname;

PostgreSQL 权限不继承：数据库 owner ≠ schema owner ≠ table owner

这一点跟SQL Server非常不一样。

举个简单的例子：

例1：

用户ccc创建了数据库db3,

用户ddd在上面建了个schema db3,然后创建了表t1.

结果用户ccc没权限查询db3.t1这张表。

You are now connected to database "db3" as user "ccc". ^

db3=> select * from db3.t1;

ERROR: permission denied for schema db3

LINE 1: select * from db3.t1;

^

db3=>

例2：

---用ddd用户连接，ddd是schema的owner,没权限读db3.t2，但可以删掉表db3.t2，真的太不一样了！！

db3=> select * from db3.t2;

ERROR: permission denied for table t2

db3=> \dt db3.*

List of tables

Schema | Name | Type | Owner

--------+------+-------+-------

db3 | t1 | table | ddd

db3 | t2 | table | eee

(2 rows)

db3=> drop table db3.t2;

DROP TABLE

db3=>