-- 229_progress_pending_review_idx.sql
-- pending_review 탭 — 미확인 오답 조회 빠르게.
-- partial 조건은 last_outcome 만, reviewed/attempted 비교는 쿼리에서 (이전 확인완료한
-- 문제가 다시 wrong/unsure 됐을 때 잡히도록 last_reviewed_at < last_attempted_at 필터).

CREATE INDEX IF NOT EXISTS idx_progress_pending_review
    ON study_question_progress (user_id, study_topic_id, last_attempted_at DESC)
    WHERE last_outcome IN ('wrong', 'unsure');