Replication in Managed Service for ClickHouse®
The process of replication is managed automatically.
By default, ClickHouse Keeper provides the same guarantees as ZooKeeper (linearizable writes, non-linearizable reads).
ClickHouse Keeper client-server protocol is compatible with ZooKeeper. However, ClickHouse Keeper snapshots and logs use a format incompatible with ZooKeeper.
ClickHouse Keeper doesn't need separate hosts to perform replication, it operates within ClickHouse® hosts themselves.
You cannot turn off ClickHouse Keeper support on your clusters.
For more information, see the ClickHouse® documentation
Create replicated tables on all hosts within your cluster. Otherwise, data loss is possible after you restore the cluster from a backup.
For more information, see Backups in ClickHouse®.
Replication for new hosts and shards
When you create a new host on your cluster, the Managed Service for ClickHouse® copies the schema to this host automatically. Then it selects a random host within the same shard and copies all the tables from the shard.
When a new shard is created, the replication sequence is the same as described above, except that a random host is selected from the first shard on the cluster.
Transfer to hosts with replicated tables
If you create a transfer to a host with a replicated table, all the new data from the transfer will be automatically replicated to all the hosts within the cluster.
See ClickHouse® sharding for more information on how to manage interactions between replicated and distributed tables in your Managed ClickHouse® cluster.