Average age of WP Croatia articles

SQL

use enwiki_p;

# 20210101: 15720/291.1
# 20210108: 15724/286.2
# 20200109: 15726/286.5
# 20200111: 15740/285.4
# 20200112: 15743/285.5
# 20200114: 15750/285.0
select count(*), avg(age)
from (
  select pa.page_id, 
  str_to_date(max(r.rev_timestamp), '%Y%m%d') as ts, 
  datediff(date '20210114', str_to_date(max(r.rev_timestamp), '%Y%m%d')) - 1 as age
  from page pa 
  inner join revision r on r.rev_page = pa.page_id
  where pa.page_namespace = 0 and pa.page_is_redirect = 0 and
  pa.page_title in 
  (
    select pt.page_title
    from page pt
    inner join categorylinks cl on cl.cl_from = pt.page_id
    where pt.page_namespace = 1 and cl.cl_to = "WikiProject_Croatia_articles"
  ) and
  r.rev_timestamp < '20210114'
  group by pa.page_id
) t
SQL

Checking query status...
