Hi all, I posted the same question on the ASF slack channel, but am posting here as well to get a quicker response.
I'm seeing an issue in query planning that it takes a long time (+5 sec) for a giant union query that has 120 subqueries in it. I captured a flame graph (attached in this email) to see where the bottleneck is, and based on the flame graph, I believe the query planner spent most of time to explore the search space of candidate plans to find the best plan. This seems because of those many subqueries in the same union query. Is my understanding correct? If so, for this particular case, it seems possible to parallelize exploring the search space. Do you have any plan for parallelizing this part? I'm not sure whether it's already done though in the master branch. I tried to search for a jira ticket on https://issues.apache.org/jira/browse/CALCITE, but couldn't find anything with my search skill. Thanks, Jihoon
