How to isolate or migrate a db to a specific monbodb shard

Environment

  • MongoDB: 4.2
  • Sharded Cluster: 2 Shards (SHARD_1, and SHARD_2. Each is a 3-node replica set)
  • Database 1: APP_DB (NOT partitioned/sharded. Located on SHARD_1)
  • Database 2: ACTIVITY_DB (partitioned/sharded activity_data collection. Located on SHARD_1 and SHARD_2)

Requirement

I want to isolate the APP_DB database from the shards that the ACTIVITY_DB database reside on. Ideally without any downtime.

The request

Could someone suggest some strategies to accomplish this? I am able to spin up additional shards if required.

Is it possible to create a SHARD_3, and make sure that data from the ACTIVITY_DB.activity_data does not migrate to SHARD3? If so, then I guess I could use movePrimary to move my APP_DB to SHARD_3.