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Common Access Management Queries

Self-managed

If you are working with self-managed ClickHouse please see SQL users and roles.

This article shows the basics of defining SQL users and roles and applying those privileges and permissions to databases, tables, rows, and columns.

Admin user​

ClickHouse Cloud services have an admin user, default, that is created when the service is created. The password is provided at service creation, and it can be reset by ClickHouse Cloud users that have the Admin role.

When you add additional SQL users for your ClickHouse Cloud service, they will need a SQL username and password. If you want them to have administrative-level privileges, then assign the new user(s) the role default_role. For example, adding user clickhouse_admin:

CREATE USER IF NOT EXISTS clickhouse_admin
IDENTIFIED WITH sha256_password BY 'P!@ssword42!';
GRANT default_role TO clickhouse_admin;
Note

When using the SQL Console, your SQL statements will not be run as the default user. Instead, statements will be run as a user named sql-console:${cloud_login_email}, where cloud_login_email is the email of the user currently running the query.

These automatically generated SQL Console users have the default role.

Passwordless authentication​

There are two roles available for SQL console: sql_console_admin with identical permissions to default_role and sql_console_read_only with read-only permissions.

Admin users are assigned the sql_console_admin role by default, so nothing changes for them. However, the sql_console_read_only role allows non-admin users to be granted read-only or full access to any instance. An admin needs to configure this access. The roles can be adjusted using the GRANT or REVOKE commands to better fit instance-specific requirements, and any modifications made to these roles will be persisted.

Granular access control​

This access control functionality can also be configured manually for user-level granularity. Before assigning the new sql_console_* roles to users, SQL console user-specific database roles matching the namespace sql-console-role:<email> should be created. For example: 

CREATE ROLE OR REPLACE sql-console-role:<email>;
GRANT <some grants> TO sql-console-role:<email>;

When a matching role is detected, it will be assigned to the user instead of the boilerplate roles. This introduces more complex access control configurations, such as creating roles like sql_console_sa_role and sql_console_pm_role, and granting them to specific users. For example:

CREATE ROLE OR REPLACE sql_console_sa_role;
GRANT <whatever level of access> TO sql_console_sa_role;
CREATE ROLE OR REPLACE sql_console_pm_role;
GRANT <whatever level of access> TO sql_console_pm_role;
CREATE ROLE OR REPLACE `sql-console-role:christoph@clickhouse.com`;
CREATE ROLE OR REPLACE `sql-console-role:jake@clickhouse.com`;
CREATE ROLE OR REPLACE `sql-console-role:zach@clickhouse.com`;
GRANT sql_console_sa_role to `sql-console-role:christoph@clickhouse.com`;
GRANT sql_console_sa_role to `sql-console-role:jake@clickhouse.com`;
GRANT sql_console_pm_role to `sql-console-role:zach@clickhouse.com`;

Test admin privileges​

Log out as the user default and log back in as user clickhouse_admin.

All of these should succeed:

SHOW GRANTS FOR clickhouse_admin;
CREATE DATABASE db1
CREATE TABLE db1.table1 (id UInt64, column1 String) ENGINE = MergeTree() ORDER BY id;
INSERT INTO db1.table1 (id, column1) VALUES (1, 'abc');
SELECT * FROM db1.table1;
DROP TABLE db1.table1;
DROP DATABASE db1;

Non-admin users​

Users should have the privileges necessary, and not all be admin users. The rest of this document provides example scenarios and the roles required.

Preparation​

Create these tables and users to be used in the examples.

Creating a sample database, table, and rows​

  1. Create a test database

    CREATE DATABASE db1;

  2. Create a table

    CREATE TABLE db1.table1 (
        id UInt64,
        column1 String,
        column2 String
    )
    ENGINE MergeTree
    ORDER BY id;

  3. Populate the table with sample rows

    INSERT INTO db1.table1
        (id, column1, column2)
    VALUES
        (1, 'A', 'abc'),
        (2, 'A', 'def'),
        (3, 'B', 'abc'),
        (4, 'B', 'def');

  4. Verify the table:

    SELECT *
    FROM db1.table1
    Query id: 475015cc-6f51-4b20-bda2-3c9c41404e49

    ┌─id─┬─column1─┬─column2─┐
    │  1 │ A       │ abc     │
    │  2 │ A       │ def     │
    │  3 │ B       │ abc     │
    │  4 │ B       │ def     │
    └────┴─────────┴─────────┘

  5. Create a regular user that will be used to demonstrate restrict access to certain columns:

    CREATE USER column_user IDENTIFIED BY 'password';

  6. Create a regular user that will be used to demonstrate restricting access to rows with certain values:

    CREATE USER row_user IDENTIFIED BY 'password';

Creating roles​

With this set of examples:

  • roles for different privileges, such as columns and rows will be created
  • privileges will be granted to the roles
  • users will be assigned to each role

Roles are used to define groups of users for certain privileges instead of managing each user separately.

  1. Create a role to restrict users of this role to only see column1 in database db1 and table1:

    CREATE ROLE column1_users;

  2. Set privileges to allow view on column1

    GRANT SELECT(id, column1) ON db1.table1 TO column1_users;

  3. Add the column_user user to the column1_users role

    GRANT column1_users TO column_user;

  4. Create a role to restrict users of this role to only see selected rows, in this case, only rows containing A in column1

    CREATE ROLE A_rows_users;

  5. Add the row_user to the A_rows_users role

    GRANT A_rows_users TO row_user;

  6. Create a policy to allow view on only where column1 has the values of A

    CREATE ROW POLICY A_row_filter ON db1.table1 FOR SELECT USING column1 = 'A' TO A_rows_users;

  7. Set privileges to the database and table

    GRANT SELECT(id, column1, column2) ON db1.table1 TO A_rows_users;

  8. grant explicit permissions for other roles to still have access to all rows

    CREATE ROW POLICY allow_other_users_filter 
    ON db1.table1 FOR SELECT USING 1 TO clickhouse_admin, column1_users;
    Note

    When attaching a policy to a table, the system will apply that policy, and only those users and roles defined will be able to do operations on the table, all others will be denied any operations. In order to not have the restrictive row policy applied to other users, another policy must be defined to allow other users and roles to have regular or other types of access.

Verification​

Testing role privileges with column restricted user​

  1. Log into the clickhouse client using the clickhouse_admin user

    clickhouse-client --user clickhouse_admin --password password

  2. Verify access to database, table and all rows with the admin user.

    SELECT *
    FROM db1.table1
    Query id: f5e906ea-10c6-45b0-b649-36334902d31d

    ┌─id─┬─column1─┬─column2─┐
    │  1 │ A       │ abc     │
    │  2 │ A       │ def     │
    │  3 │ B       │ abc     │
    │  4 │ B       │ def     │
    └────┴─────────┴─────────┘

  3. Log into the ClickHouse client using the column_user user

    clickhouse-client --user column_user --password password

  4. Test SELECT using all columns

    SELECT *
    FROM db1.table1
    Query id: 5576f4eb-7450-435c-a2d6-d6b49b7c4a23

    0 rows in set. Elapsed: 0.006 sec.

    Received exception from server (version 22.3.2):
    Code: 497. DB::Exception: Received from localhost:9000. 
    DB::Exception: column_user: Not enough privileges. 
    To execute this query it's necessary to have grant 
    SELECT(id, column1, column2) ON db1.table1. (ACCESS_DENIED)
    Note

    Access is denied since all columns were specified and the user only has access to id and column1

  5. Verify SELECT query with only columns specified and allowed:

    SELECT
        id,
        column1
    FROM db1.table1
    Query id: cef9a083-d5ce-42ff-9678-f08dc60d4bb9

    ┌─id─┬─column1─┐
    │  1 │ A       │
    │  2 │ A       │
    │  3 │ B       │
    │  4 │ B       │
    └────┴─────────┘

Testing role privileges with row restricted user​

  1. Log into the ClickHouse client using row_user

    clickhouse-client --user row_user --password password

  2. View rows available

    SELECT *
    FROM db1.table1
    Query id: a79a113c-1eca-4c3f-be6e-d034f9a220fb

    ┌─id─┬─column1─┬─column2─┐
    │  1 │ A       │ abc     │
    │  2 │ A       │ def     │
    └────┴─────────┴─────────┘
    Note

    Verify that only the above two rows are returned, rows with the value B in column1 should be excluded.

Modifying Users and Roles​

Users can be assigned multiple roles for a combination of privileges needed. When using multiple roles, the system will combine the roles to determine privileges, the net effect will be that the role permissions will be cumulative.

For example, if one role1 allows for only select on column1 and role2 allows for select on column1 and column2 then the user will have access to both columns.

  1. Using the admin account, create new user to restrict by both row and column with default roles

    CREATE USER row_and_column_user IDENTIFIED BY 'password' DEFAULT ROLE A_rows_users;

  2. Remove prior privileges for A_rows_users role

    REVOKE SELECT(id, column1, column2) ON db1.table1 FROM A_rows_users;

  3. Allow A_row_users role to only select from column1

    GRANT SELECT(id, column1) ON db1.table1 TO A_rows_users;

  4. Log into the ClickHouse client using row_and_column_user

    clickhouse-client --user row_and_column_user --password password;

  5. Test with all columns:

    SELECT *
    FROM db1.table1
    Query id: 8cdf0ff5-e711-4cbe-bd28-3c02e52e8bc4

    0 rows in set. Elapsed: 0.005 sec.

    Received exception from server (version 22.3.2):
    Code: 497. DB::Exception: Received from localhost:9000. 
    DB::Exception: row_and_column_user: Not enough privileges. 
    To execute this query it's necessary to have grant 
    SELECT(id, column1, column2) ON db1.table1. (ACCESS_DENIED)

  6. Test with limited allowed columns:

    SELECT
        id,
        column1
    FROM db1.table1
    Query id: 5e30b490-507a-49e9-9778-8159799a6ed0

    ┌─id─┬─column1─┐
    │  1 │ A       │
    │  2 │ A       │
    └────┴─────────┘

Troubleshooting​

There are occasions when privileges intersect or combine to produce unexpected results, the following commands can be used to narrow the issue using an admin account

Listing the grants and roles for a user​

SHOW GRANTS FOR row_and_column_user
Query id: 6a73a3fe-2659-4aca-95c5-d012c138097b

┌─GRANTS FOR row_and_column_user───────────────────────────┐
│ GRANT A_rows_users, column1_users TO row_and_column_user │
└──────────────────────────────────────────────────────────┘

List roles in ClickHouse​

SHOW ROLES
Query id: 1e21440a-18d9-4e75-8f0e-66ec9b36470a

┌─name────────────┐
│ A_rows_users    │
│ column1_users   │
└─────────────────┘

Display the policies​

SHOW ROW POLICIES
Query id: f2c636e9-f955-4d79-8e80-af40ea227ebc

┌─name───────────────────────────────────┐
│ A_row_filter ON db1.table1             │
│ allow_other_users_filter ON db1.table1 │
└────────────────────────────────────────┘

View how a policy was defined and current privileges​

SHOW CREATE ROW POLICY A_row_filter ON db1.table1
Query id: 0d3b5846-95c7-4e62-9cdd-91d82b14b80b

┌─CREATE ROW POLICY A_row_filter ON db1.table1────────────────────────────────────────────────┐
│ CREATE ROW POLICY A_row_filter ON db1.table1 FOR SELECT USING column1 = 'A' TO A_rows_users │
└─────────────────────────────────────────────────────────────────────────────────────────────┘

Example commands to manage roles, policies, and users​

The following commands can be used to:

  • delete privileges
  • delete policies
  • unassign users from roles
  • delete users and roles
Tip

Run these commands as an admin user or the default user

Remove privilege from a role​

REVOKE SELECT(column1, id) ON db1.table1 FROM A_rows_users;

Delete a policy​

DROP ROW POLICY A_row_filter ON db1.table1;

Unassign a user from a role​

REVOKE A_rows_users FROM row_user;

Delete a role​

DROP ROLE A_rows_users;

Delete a user​

DROP USER row_user;

Summary​

This article demonstrated the basics of creating SQL users and roles and provided steps to set and modify privileges for users and roles. For more detailed information on each please refer to our user guides and reference documentation.