db: nex indexes to speed up certificate generation
db: nex indexes to speed up certificate generation

be-oi/beoi-contest-platform,France-ioi/bebras-platform,be-oi/beoi-contest-platform,France-ioi/bebras-platform,be-oi/beoi-contest-platform,France-ioi/bebras-platform,France-ioi/bebras-platform,France-ioi/bebras-platform,be-oi/beoi-contest-platform,France-ioi/bebras-platform,be-oi/beoi-contest-platform,be-oi/beoi-contest-platform