I actually ended up doing something a little different as I wanted more info and UNION proved a bit restrictive. I also wanted to break it down by groups. I achieved success (I think) by hacking the included Active Lurkers query with another one I have for extracting group specific info:
-- [params]
-- int :number_of_days = 365
-- string :group_name = trust_level_0
With included_users AS (
SELECT
gu.user_id
FROM group_users gu
JOIN groups g
ON g.id = gu.group_id
WHERE g.name = :group_name
),
posts_by_user AS (
SELECT COUNT(*) AS posts, p.user_id
FROM posts p
LEFT JOIN topics t ON t.id = p.topic_id
WHERE p.created_at::date > CURRENT_TIMESTAMP - INTERVAL ':number_of_days' day
AND t.deleted_at IS NULL
AND t.visible = TRUE
AND t.closed = FALSE
AND t.archived = FALSE
AND t.archetype = 'regular'
AND p.deleted_at IS NULL
GROUP BY p.user_id
),
posts_read_by_user AS (
SELECT SUM(posts_read) AS posts_read, uv.user_id
FROM user_visits uv
WHERE uv.posts_read > 0
AND uv.visited_at > CURRENT_TIMESTAMP - INTERVAL ':number_of_days' day
GROUP BY uv.user_id
)
SELECT
u.id AS "user_id",
u.username_lower AS "username",
u.last_seen_at,
COALESCE(pbu.posts, 0) AS "posts_created",
COALESCE(prbu.posts_read, 0) AS "posts_read"
FROM users u
LEFT JOIN posts_by_user pbu ON pbu.user_id = u.id
LEFT JOIN posts_read_by_user prbu ON prbu.user_id = u.id
WHERE u.active = true
AND u.id > 0
AND u.id IN (SELECT user_id FROM included_users)
AND (COALESCE(pbu.posts, 0) > 0 OR COALESCE(prbu.posts_read, 0) > 0)
ORDER BY u.id