Understanding query-context finalize (and why it is always false on historicals)

Hi all,

in my company we’re currently working with a druid-cluster and we want to understand how to improve query performance.

When testing out different configurations, I was spending more time with query-logs on broker and historical site and noticed, that all the queries had their query-context field ‘finalize’ set to false,

even though the broker specifically set it to true. (In these tests there was 1 broker and 6 historicals, the logs are only from one historical)

At first I thought this was only due to the fact, it was a hyperUnique metric and thus finalizing makes it incorrect for the broker (which I assume does the merging of the registers), but even for longSums it is never set to true.

So I wonder why this is the way it is, whether it has performance issues on queries or whether this is the intended behavior ?

PrintScreen for hyperunique, top part is historical, bottom part is broker.

PrintScreen for longsum, top part is historical, bottom part is broker.

Thanks in advance,

André