Query: ibm_is_volume_storage_by_creation_month

with volumes as (
  select
    title,
    capacity,
    created_at,
    to_char(created_at, 'YYYY-MM') as creation_month
  from
    ibm_is_volume
),
months as (
  select
    to_char(d, 'YYYY-MM') as month
  from
    generate_series(
      date_trunc(
        'month',
        (
          select
            min(created_at)
          from
            volumes
        )
      ),
      date_trunc('month', current_date),
      interval '1 month'
    ) as d
),
volumes_by_month as (
  select
    creation_month,
    sum(capacity) as size
  from
    volumes
  group by
    creation_month
)
select
  months.month,
  volumes_by_month.size as "GB"
from
  months
  left join volumes_by_month on months.month = volumes_by_month.creation_month
order by
  months.month;