CREATE OR REPLACE FUNCTION prevent_dashboard_version_mutation() RETURNS trigger AS $$
BEGIN
    RAISE EXCEPTION 'dashboard versions are immutable';
END;
$$ LANGUAGE plpgsql;

CREATE OR REPLACE TRIGGER dashboard_versions_immutable_update
    BEFORE UPDATE ON dashboard_versions
    FOR EACH ROW EXECUTE FUNCTION prevent_dashboard_version_mutation();

CREATE INDEX IF NOT EXISTS dashboard_versions_created_at_idx ON dashboard_versions (dashboard_id, created_at DESC, version_number DESC);