Pagination is costly than polling (query) every 15 seconds

is that good design to poll every 15 seconds and look for orders older than current date to archival date(data is around 500k per day) and or do pagination as bulk by every day nighly job

  1. pagination is costly than polling ?
  2. polling means every 15 seconds we are querying data and look for old orders which is bad design than implement pagination
  3. while implementing pagination will that cause any operation blocks or timeout? do we need more memory since we store data in memory