Combining multiple policies per user

RLS in Amazon Redshift supports attaching multiple policies per user and object. When there are multiple policies defined for a user, Amazon Redshift applies all the policies with either AND or OR syntax depending on the RLS CONJUNCTION TYPE setting for the table. For more information about conjunction type, see ALTER TABLE.

Multiple policies on a table can be associated with you. Either multiple policies are directly attached to you, or you belong to multiple roles, and the roles have different policies attached to them.

When the multiple policies should restrict rows access in a given relation, you can set RLS CONJUNCTION TYPE of the relation to AND. Consider the following example. Alice can only see Sports event that has a "catname" of NBA as the policy specified.

-- Create an analyst role and grant it to a user named Alice.
CREATE ROLE analyst;
CREATE USER alice WITH PASSWORD 'Name_is_alice_1';
GRANT ROLE analyst TO alice;

-- Create an RLS policy that only lets the user see sports.
CREATE RLS POLICY policy_sports
WITH (catgroup VARCHAR(10))
USING (catgroup = 'Sports');

-- Create an RLS policy that only lets the user see NBA.
CREATE RLS POLICY policy_nba
WITH (catname VARCHAR(10))
USING (catname = 'NBA');

-- Attach both to the analyst role.
ATTACH RLS POLICY policy_sports ON category TO ROLE analyst;
ATTACH RLS POLICY policy_nba ON category TO ROLE analyst;

-- Activate RLS on the category table with AND CONJUNCTION TYPE. 
ALTER TABLE category ROW LEVEL SECURITY ON CONJUNCTION TYPE AND;

-- Change session to Alice.
SET SESSION AUTHORIZATION alice;

-- Select all from the category table.
SELECT catgroup, catname
FROM category;

 catgroup | catname 
---------+---------
 Sports   | NBA
(1 row)

When the multiple policies should permit the users to see more rows in a given relation, user can set RLS CONJUNCTION TYPE of the relation to OR. Consider the following example. Alice can only see "Concerts" and "Sports" as the policy specified.

-- Create an analyst role and grant it to a user named Alice.
CREATE ROLE analyst;
CREATE USER alice WITH PASSWORD 'Name_is_alice_1';
GRANT ROLE analyst TO alice;

-- Create an RLS policy that only lets the user see concerts.
CREATE RLS POLICY policy_concerts
WITH (catgroup VARCHAR(10))
USING (catgroup = 'Concerts');

-- Create an RLS policy that only lets the user see sports.
CREATE RLS POLICY policy_sports
WITH (catgroup VARCHAR(10))
USING (catgroup = 'Sports');

-- Attach both to the analyst role.
ATTACH RLS POLICY policy_concerts ON category TO ROLE analyst;
ATTACH RLS POLICY policy_sports ON category TO ROLE analyst;

-- Activate RLS on the category table with OR CONJUNCTION TYPE. 
ALTER TABLE category ROW LEVEL SECURITY ON CONJUNCTION TYPE OR;

-- Change session to Alice.
SET SESSION AUTHORIZATION alice;

-- Select all from the category table.
SELECT catgroup, count(*)
FROM category
GROUP BY catgroup ORDER BY catgroup;

 catgroup | count 
---------+-------
 Concerts |  3
 Sports   |  5
(2 rows)