Merge is happening more on replica. I have only 1 replica with 6 nodes with 3 shards. I just switched over 5.2 from 1.7 and Saw that replica nodes are having more merge and more fetch too.
This is degrading my bulk index performance. My Through put is as below
Merge on Primary : 0.6k
Merge On Replicas : 4.5k
Merge Docs On Replica : 2M
Merge Docs on Primary : 1M
I am running with highest possible Threads and queue Configuration
CPU 16 core and memory 30 GB per node
Can somebody help me to understand it.