Query: efs_file_system_by_age

with file_systems as (
  select
    title,
    creation_time,
    to_char(creation_time, 'YYYY-MM') as creation_month
  from
    aws_efs_file_system
),
months as (
  select
    to_char(d, 'YYYY-MM') as month
  from
    generate_series(
      date_trunc('month',
        (
          select
            min(creation_time)
          from file_systems
        )
      ),
      date_trunc('month', current_date),
      interval '1 month'
    ) as d
),
file_systems_by_month as (
  select
    creation_month,
    count(*)
  from
    file_systems
  group by
    creation_month
)
select
  months.month,
  file_systems_by_month.count
from
  months
  left join file_systems_by_month on months.month = file_systems_by_month.creation_month
order by
  months.month;