Grant SELECT on all tables in Redshift

You need the USAGE privilege (at least) for the schema as well:

GRANT USAGE ON SCHEMA something TO GROUP data_viewers;

Related Postgres example:

• Permission for sequence in another schema

Remember you only granted permissions to already existing tables. Does not apply to tables created later. To cover those, too:

ALTER DEFAULT PRIVILEGES FOR USER role_that_creates_tables
IN SCHEMA public
GRANT SELECT ON TABLES TO GROUP data_viewers;

Amazon Redshift implemented DEFAULT PRIVILEGES as well.

Here is a complete cookbook for Postgres:

• How to manage DEFAULT PRIVILEGES for USERs on a DATABASE vs SCHEMA?

Be aware of some differences between mainline Postgres and Redshift! Redshift sticks to separate users and groups, while Postgres replaced that with the universal concept of roles:

• Why did PostgreSQL merge users and groups into roles?

And I am not sure how Redshift handles sequences ...

I had the same need for a Redshift read-only user. After reading the docs, I came up with a set of queries:

-- Create Read-Only Group     
CREATE GROUP ro_group;

-- Create User
CREATE USER ro_user WITH password PASSWORD;

-- Add User to Read-Only Group
ALTER GROUP ro_group ADD USER ro_user;

-- Grant Usage permission to Read-Only Group to specific Schema
GRANT USAGE ON SCHEMA "ro_schema" TO GROUP ro_group;

-- Grant Select permission to Read-Only Group to specific Schema
GRANT SELECT ON ALL TABLES IN SCHEMA "ro_schema" TO GROUP ro_group;

-- Alter Default Privileges to maintain the permissions on new tables
ALTER DEFAULT PRIVILEGES IN SCHEMA "ro_schema" GRANT SELECT ON TABLES TO GROUP ro_group;

-- Revoke CREATE privileges from group
REVOKE CREATE ON SCHEMA "ro_schema" FROM GROUP ro_group;

If you want to actually remove the user later on, you have to pretty much go backwards.