-- Per-manga sync-state derivation joins crawler_jobs to manga_sources via
-- (payload->>'source_id', payload->>'source_manga_key') for the
-- `sync_manga` job kind (whose payload doesn't carry a manga_id directly).
-- Without this index the join falls back to a seqscan of crawler_jobs on
-- every admin manga listing — a noticeable cost as the job table grows
-- with the daily metadata pass.
--
-- Partial on `state IN ('pending','running')` so it covers only in-flight
-- jobs (the bulk of the table is done/dead and irrelevant to "is this
-- manga being synced right now").
CREATE INDEX crawler_jobs_sync_manga_key_idx
    ON crawler_jobs ((payload->>'source_manga_key'))
 WHERE state IN ('pending', 'running')
   AND payload->>'kind' = 'sync_manga';