MongoDB Sharded Cluster Scaling
We are implementing scale for our sharded cluster environment wherein we add nodes and add shards to the cluster. Each node has only 3 shards. So for example, our minimum number of nodes is 3, so each node has three shards (shards 1-3 are found in each shard). During scale out, we add 1 node and increase number of shards by 1. Each node will still have three shards (node1: shard1,2,3, node2: shard1,2,4, node3: shard1,3,4, node4: shard2,3,4).
Now my problem is how to scale in from 4 nodes to 3 nodes.
How will we merge data from shard 4 to shards1-3?
Is this possible?