My understanding is the node receiving the REST query will act as a coordinating node.
Is this assumption false?
What I'm trying to do is to force say 3 nodes to handle both ingest and coordinating functions. Those 3 nodes are not data nodes. For the sake of this discussion, we can leave out ingest function because I can simply split it into 3 new nodes.
From my experience, the CPU pressure is not on the 3 nodes receiving query when I'm performing CPU intensive aggregations.
If my setup is wrong, how can I achieve forcing coordination from certain none-data nodes?
The purpose is pretty simple. Have data nodes only to gather data. Leave aggregation to none-data nodes.
This way, I can scale them differently based on query need.