-- 376_quiz_session_client_uuid_uq.sql
-- (client_session_uuid, study_topic_id) 유일 — 뷰어 1세션이 topic 별 1 DS세션. partial(uuid 있는 viewer 행만).
CREATE UNIQUE INDEX IF NOT EXISTS study_quiz_sessions_client_uuid_topic_uq ON study_quiz_sessions (client_session_uuid, study_topic_id) WHERE client_session_uuid IS NOT NULL;