CREATE ROW POLICY

Creates a row policy, i.e. a filter used to determine which rows a user can read from a table.

:::tip Row policies make sense only for users with readonly access. If a user can modify a table or copy partitions between tables, it defeats the restrictions of row policies. :::

Syntax:

CREATE [ROW] POLICY [IF NOT EXISTS | OR REPLACE] policy_name1 [ON CLUSTER cluster_name1] ON [db1.]table1|db1.*
        [, policy_name2 [ON CLUSTER cluster_name2] ON [db2.]table2|db2.* ...]
    [IN access_storage_type]
    [FOR SELECT] USING condition
    [AS {PERMISSIVE | RESTRICTIVE}]
    [TO {role1 [, role2 ...] | ALL | ALL EXCEPT role1 [, role2 ...]}]

USING Clause {#using-clause}

Allows specifying a condition to filter rows. A user will see a row if the condition is calculated to non-zero for the row.

TO Clause {#to-clause}

In the TO section you can provide a list of users and roles this policy should work for. For example, CREATE ROW POLICY ... TO accountant, john@localhost.

Keyword ALL means all the ClickHouse users, including current user. Keyword ALL EXCEPT allows excluding some users from the all users list, for example, CREATE ROW POLICY ... TO ALL EXCEPT accountant, john@localhost

AS Clause {#as-clause}

It's allowed to have more than one policy enabled on the same table for the same user at one time. So we need a way to combine the conditions from multiple policies.

By default, policies are combined using the boolean OR operator. For example, the following policies:

CREATE ROW POLICY pol1 ON mydb.table1 USING b=1 TO mira, peter
CREATE ROW POLICY pol2 ON mydb.table1 USING c=2 TO peter, antonio

enable the user peter to see rows with either b=1 or c=2.

The AS clause specifies how policies should be combined with other policies. Policies can be either permissive or restrictive. By default, policies are permissive, which means they are combined using the boolean OR operator.

A policy can be defined as restrictive as an alternative. Restrictive policies are combined using the boolean AND operator.

Here is the general formula:

row_is_visible = (one or more of the permissive policies' conditions are non-zero) AND
                 (all of the restrictive policies's conditions are non-zero)

For example, the following policies:

CREATE ROW POLICY pol1 ON mydb.table1 USING b=1 TO mira, peter
CREATE ROW POLICY pol2 ON mydb.table1 USING c=2 AS RESTRICTIVE TO peter, antonio

enable the user peter to see rows only if both b=1 AND c=2.

Database policies are combined with table policies.

For example, the following policies:

CREATE ROW POLICY pol1 ON mydb.* USING b=1 TO mira, peter
CREATE ROW POLICY pol2 ON mydb.table1 USING c=2 AS RESTRICTIVE TO peter, antonio

enable the user peter to see table1 rows only if both b=1 AND c=2, although any other table in mydb would have only b=1 policy applied for the user.

ON CLUSTER Clause {#on-cluster-clause}

Allows creating row policies on a cluster, see Distributed DDL.

Examples {#examples}

CREATE ROW POLICY filter1 ON mydb.mytable USING a<1000 TO accountant, john@localhost

CREATE ROW POLICY filter2 ON mydb.mytable USING a<1000 AND b=5 TO ALL EXCEPT mira

CREATE ROW POLICY filter3 ON mydb.mytable USING 1 TO admin

CREATE ROW POLICY filter4 ON mydb.* USING 1 TO admin