-- 2026-05-20 PR-Worker-Pool-Registry-1B: worker_jobs claim 핫패스 partial index.
-- claim 쿼리: WHERE status='pending' AND job_type=$1 ORDER BY created_at LIMIT 1 FOR UPDATE SKIP LOCKED.
-- partial index = pending row 만 색인 (테이블 성장과 무관 — completed/failed row 누적해도 인덱스 크기 일정).

CREATE INDEX IF NOT EXISTS idx_worker_jobs_pending_type
    ON worker_jobs (job_type, created_at)
    WHERE status = 'pending';