Bir tahlilchi tomonidan yozilgan SQL so'rov berilgan. So'rovdagi noeffektivliklarni aniqlang va ularni qanday oldini olish mumkinligini taklif qiling. So'rov ikki jadvalni birlashtiradi: - 'events' fakt jadvali, kalit 'event_id' - trafik manbai referensiya jadvali, kalit 'referer_str' Ikkala jadvalda milliardlab yozuvlar mavjud. select * from (select distinct e.event_id, e.user_id, e.category_id, e.location_id, s.source_name, s.medium_name, s.campaign_name, row_number() over(partition by e.event_id, e.user_id, e.category_id, e.location_id, s.source_name, s.medium_name, s.campaign_name) as rnk from events e left join traffic_source s on e.referer_str = s.referer_str where e.event_date = current_date() - 1 group by 1,2,3,4,5,6,7) t where rnk = 1