Could you let me know how to process "Query Phase" exactly when an index has replicas?
For all I know, The coordinating node sends Query to every shard for Query Phase.
I want to understand the exact meaning of every shard for Query phase.
For example, an Index of 2 shards(P0, P1) and 1 replica(R0, R1) is allocated in 4 Nodes like below.
- Node_A : P1
- Node_B : R0
- Node_C : R1
- Node_D : P0
Let's suppose that Node_C receives a search request(i.e., Node_C is the coordinating node now).
Q1 : Does Node_C send Query request to all shards(P1, R0, R1, P0) or to just 2 shards(e.g., "P1 and R0" or "R1 and P0")?
If the latter, how does ES decide 2 shards to send Query request?
Q2 : If the query type is DFS_Query_then_Fetch, are the target shards for Pre-Query also same with the shards for Query?
Thanks for your help always.