This message was deleted.

Hi Udit, There is an experimental feature in Druid called "Cold Tier", still currently under development ... if you set up your datasource retention to store older data with zero "0" replicas it will display a Cold Tier percentage for the data source (see screenshots). The segments in Cold Tier won't be loaded onto Historials ... and the regular query engine will not see them or be able to query them ... but the MSQ query engine will see them and be able to query them directly from deep storage. The MSQ query is still using task slots, but not reserving them in the way the other Druid servers are. There is an API you can use to submit MSQ tasks ... what I don't know is if the current version of the API can be used to issue queries, or only ingestion tasks (with little return data).

It can be used to issue queries: https://druid.apache.org/docs/latest/multi-stage-query/api.html Although plain SELECT queries are experimental currently. We would love your feedback on them! Just be aware the API is likely to evolve for plain SELECT in future, possibly in a backwards-incompatible way

@John Kowtko when i say older data, i mean it is still in retention, hence available on historical. but i want to ran long running query against this data without affecting the live traffic. as these queries are slow, it held up the historical processing threads which affects my live queries on this node, and we start getting time out errors, to avoid this i was wondering if at all i can run the query piece of code in a way where i can give it list of segments along with query to execute, so i can even ran it completely outside the druid cluster. does it make sense to you ?

Okay, there is Query Laning ... https://druid.apache.org/docs/latest/operations/mixed-workloads.html#query-laning that might be more related to what you are looking for.