Query: emr_cluster_by_age

with clusters as (
  select
    title,
    (status -> 'Timeline' ->> 'CreationDateTime')::timestamp as created_at,
    to_char((status -> 'Timeline' ->> 'CreationDateTime')::timestamp, 'YYYY-MM') as creation_month
  from
    aws_emr_cluster
),
months as (
  select
    to_char(d, 'YYYY-MM') as month
  from
    generate_series(
      date_trunc('month',
        (select min(created_at) from clusters)
      ),
      date_trunc('month', current_date),
      interval '1 month'
    ) as d
),
clusters_by_month as (
  select
    creation_month,
    count(*)
  from
    clusters
  group by
    creation_month
)
select
  months.month,
  clusters_by_month.count
from
  months
  left join clusters_by_month on months.month = clusters_by_month.creation_month
order by
  months.month;