sql-date-ranges-naive.sql

with source as
(
  select * from ecds_db.playground.time11M
),
timeline as
(
  select start_at as moment
  from source
  union
  select end_at as moment
  from source
),
concurrency as
(
  select t.moment, count(s.id) as count 
  from timeline t
  join source s on t.moment between s.start_at and s.end_at
  group by t.moment
)
select max(count)
from concurrency