begin;
create type task_record as (
    task_id bigint,
    task_policy task_policy,
    task_status task_status,
    task_run_id bigint,
    arguments jsonb,
    type text,
    backend_id text,
    metadata jsonb,
    scheduled timestamptz,
    started timestamptz,
    ended timestamptz
);

create or replace function swh_scheduler_task_to_archive(
  ts timestamptz, last_id bigint default -1, lim bigint default 10)
  returns setof task_record
  language sql
as $$
   select t.id as task_id, t.policy as task_policy,
          t.status as task_status, tr.id as task_run_id,
          t.arguments, t.type, tr.backend_id, tr.metadata,
          tr.scheduled, tr.started, tr.ended
   from task t inner join task_run tr on t.id=tr.task
   where ((t.policy = 'oneshot' and t.status ='completed') or
          (t.policy = 'recurring' and t.status ='disabled')) and
          tr.ended < ts and
          t.id > last_id
   order by t.id
   limit lim;
$$;


select * from swh_scheduler_task_to_archive('2016-02-23'::timestamptz);  -- fine


select * from swh_scheduler_task_to_archive('2016-02-22'::timestamptz);  -- hangs

  select t.id as task_id, t.policy as task_policy,
          t.status as task_status, tr.id as task_run_id,
          t.arguments, t.type, tr.backend_id, tr.metadata,
          tr.scheduled, tr.started, tr.ended
   from task t inner join task_run tr on t.id=tr.task
   where ((t.policy = 'oneshot' and t.status ='completed') or
          (t.policy = 'recurring' and t.status ='disabled')) and
          tr.ended < '2016-02-22' and
          t.id > -1
   order by t.id
   limit 10;  -- fine, no data

  select t.id as task_id, t.policy as task_policy,
          t.status as task_status, tr.id as task_run_id,
          t.arguments, t.type, tr.backend_id, tr.metadata,
          tr.scheduled, tr.started, tr.ended
   from task t inner join task_run tr on t.id=tr.task
   where ((t.policy = 'oneshot' and t.status ='completed') or
          (t.policy = 'recurring' and t.status ='disabled')) and
          tr.ended < '2016-02-23' and
          t.id > -1
   order by t.id
   limit 10;  -- fine

rollback;