Query: rds_instances_for_rds_db_instance_snapshot

 with rds_db_instance as (
  select
    arn,
    resource_id,
    region,
    account_id
  from
    aws_rds_db_instance
  order by
    arn,
    resource_id,
    region,
    account_id
), rds_db_snapshot as (
  select
    arn,
    dbi_resource_id,
    region,
    account_id
  from
    aws_rds_db_snapshot
  where
    arn = $1
    and account_id = split_part($1, ':', 5)
    and region = split_part($1, ':', 4)
  order by
    arn,
    dbi_resource_id,
    region,
    account_id
)
select
  i.arn as rds_instance_arn
from
  rds_db_instance as i
  join rds_db_snapshot as s on s.dbi_resource_id = i.resource_id;