Is there a way to visualise or to know how a nested query been taken care of in Druid. We have a nested query and both has groupby based on time an another dimension. We would like to know if the merge is happening at historical or broker.
How does the merging exactly work here?
Is there a way we can know per query. Execution plan does provide how the query is broken into . can we get info based on that as to what part of the execution plan executes where?
Thanks in advance
Here is the information I found from online doc:
Nested groupBys (dataSource of type “query”) are performed differently for “v1” and “v2”. The Broker first runs the inner groupBy query in the usual way. “v1” strategy then materializes the inner query’s results on-heap with Druid’s indexing mechanism, and runs the outer query on these materialized results. “v2” strategy runs the outer query on the inner query’s results stream with off-heap fact map and on-heap string dictionary that can spill to disk. Both strategy perform the outer query on the Broker in a single-threaded fashion.
Hope this helps
Thanks Ming. But this still does not give clear visualisation of the query how it's executed. Is there a way to visualise this ?