Found it. It is the function “site_aggregates_activity” which essentially says if you have published a comment or a post since the target time (day, month, 6 month etc) you are considered active. Here is the code

select c.creator_id from comment c inner join person u on c.creator_id = u.id where c.published > (‘now’::timestamp - i::interval) and u.local = true union select p.creator_id from post p inner join person u on p.creator_id = u.id where p.published > (‘now’::timestamp - i::interval) and u.local = true

I couldn’t find anything. I’m sure it is in the code here somewhere but can’t find it in there either. https://codeberg.org/thefederationinfo/the-federation.info

Looks like the data actually is calculated by lemmy not the logging tool as it is just the stats from the Aussie Zone public api…

Eg. id":1,“site_id”:1,“users”:1319,“posts”:1228,“comments”:13307,“communities”:32,“users_active_day”:170,“users_active_week”:300,“users_active_month”:481,“users_active_half_year”:481}

So the answer would actually be in the lemmy documentation…