ALTER TABLE alert_occurrences
    DROP CONSTRAINT alert_occurrences_event_type_check;

ALTER TABLE alert_occurrences
    ADD CONSTRAINT alert_occurrences_event_type_check
    CHECK (event_type IN ('evaluation', 'transition', 'acknowledge', 'unacknowledge'));

CREATE INDEX alert_instances_acknowledged_idx ON alert_instances (acknowledged_at DESC, id ASC) WHERE current_state = 'acknowledged';