慢SQL查询，如何改进？

Question

我实际上试图改进这些SQL查询。它们各持续5秒钟，因为表“admin_event_visits”的行数超过1.5十亿。

有没有办法优化这些查询？

1

SELECT COUNT(distinct ip) AS count_distinct_ip, (DATE_TRUNC('day', (created_at::timestamptz - INTERVAL '0 second')
AT TIME ZONE  'America/Chicago')+ INTERVAL '0 second') AT TIME ZONE 'America/Chicago' AS day FROM "admin_event_visits"
WHERE (created_at IS NOT NULL) GROUP BY (DATE_TRUNC('day', (created_at::timestamptz - INTERVAL '0 second')
AT TIME ZONE 'America/Chicago') + INTERVAL '0 second') AT TIME ZONE 'America/Chicago'

2

SELECT COUNT(*) AS count_all, (DATE_TRUNC('day', (created_at::timestamptz - INTERVAL '0 second') 
AT TIME ZONE 'America/Chicago') + INTERVAL '0 second') AT TIME ZONE 'America/Chicago' AS day FROM "admin_event_visits"
WHERE (created_at IS NOT NULL) GROUP BY (DATE_TRUNC('day', (created_at::timestamptz - INTERVAL '0 second') 
AT TIME ZONE 'America/Chicago') + INTERVAL '0 second') AT TIME ZONE 'America/Chicago'

3

SELECT COUNT(distinct ip) AS count_distinct_ip, (DATE_TRUNC('day', (created_at::timestamptz - INTERVAL '0 second')
AT TIME ZONE 'America/Chicago') + INTERVAL '0 second') AT TIME ZONE 'America/Chicago' AS day
FROM "admin_event_visits"
WHERE device = 'mobile' AND (created_at IS NOT NULL)
GROUP BY (DATE_TRUNC('day', (created_at::timestamptz - INTERVAL '0 second')
AT TIME ZONE 'America/Chicago') + INTERVAL '0 second') AT TIME ZONE 'America/Chicago'