Hello TEAM In our production we are using SET useMultistageEngine = True and because of that we are getting stability issue of cluster with below error HelixManager is not connected ZK session expired can you advice below query really required useMultistageEngine = True SELECT toEpochSeconds(DATETRUNC('hour', event_time)) AS event_time_hours, state, COUNT(1) as state_count FROM event_details WHERE event_time >= %(start_time) AND oevent_time < %(end_time) GROUP BY toEpochSeconds(DATETRUNC('hour', event_time)), state OPTION(timeoutMs=300000)

This query should not need MSQE. How many docs does this query select and how many hours are you grouping

It can be 24 to 30 hours max

Then this query should be fast. Do you have range index on event_time?

It's segments column Do we need range index for the same Also do we need range index for non segments timeapec column?