You can set multiple tiers to load segment to (for the same interval). i.e.

{
  "type": "loadByInterval",
  "interval": "2012-01-01/2013-01-01",
  "tieredReplicants": {
    "hot": 1,
    "_default_tier": 1
  }
}

My question is does Druid prioritize reading data from hot (or a specific tier) when querying the data? EDIT: nvm. found out the answer. There is

druid.server.priority

property