Data migration in the DDS typically involves copying or migrating data from one instance (source) to another (target). The following are some common data migration schemes for the DDS:
Backup and restore: The mongodump tool is used to create a backup from the source database, and then the mongorestore tool is used to restore the backup data to the target database. This approach is suitable for small-scale data migration and will not cause service interrupt to production environments. However, for large-scale or real-time production systems, backup and restore may require extended data migration duration and downtime.
Data migration based on replica sets: If you use a replica set, you can implement data migration by adding new target nodes (Secondary nodes). In a replica set, data is automatically copied to the Secondary node, so you can gradually migrate data to the new target node. Once all the data has been copied to the new node, the node can be upgraded to the Primary node to complete the data migration.
Data migration based on Sharding: If Sharding is used, you can implement data migration by adding new Shards. In a Sharded cluster, you can first add an empty Shard, and then gradually migrate data to the new Shard. Once all the data has been Migration to the new node, the original Shard can be removed to complete data migration.