row_level_security.md

Row Level Security (PostgreSQL)

In this document, we present some Row Level Security (RLS) features available in PostgreSQL but currently not used in the Vibetype project.

Disabling RLS

RLS is disabled per table by this command:

ALTER TABLE <table_name> DISABLE ROW LEVEL SECURITY;

Permissive and restrictive policies

All policies currently defined in Vibetype are so-called permissive policies, which means that their conditions define a set of rows that are allowed to be selected or modified.

We could explicitly define a policy as permissive by adding the AS PERMISSIVE clause, e.g.

CREATE POLICY account_block_all ON vibetype.account_block AS PERMISSIVE FOR ALL
USING (
  created_by = vibetype.invoker_account_id()
);

However, this is not done in Vibetype since permissive is also the default.

While permissive policies define conditions telling us which rows should be visible, restrictive policies start from a set of visible rows (given by at least one permissive policy) and define conditions telling us which rows should NOT be seen. In a CREATE POLICY statement, the AS RESTRICTIVE clause must be used to define a restrictive policy. If multiple restrictive policies apply, they are logically connected by AND.

See https://www.postgresql.org/docs/17/sql-createpolicy.html for more details on restrictive policies.