**Use case**

Currently, `system.replicas` table has `total_replicas` and `active_replicas` columns which are useful to check/alert when some replicas are down. One problem, these columns are numbers. They tell when there is a problem, but you need to further check ZooKeeper or query all the nodes to detect what exact replicas (hosts) are down/inactive/have problems.

**Describe the solution you'd like**

Add a replicas column maybe as a map which would contain the replica name, and it's status. Or, add 2 array columns with `replica_names` and `active_replica_names`

**Alternative**

Something along the line

```sql
select path, value from system.zookeeper where path IN (
    select concat(path, '/', name) from system.zookeeper where path in (select concat(zookeeper_path, '/replicas') from system.replicas)
)
and name = 'is_active'
```
dummy_alter.metadata_str = source_metadata;
    dummy_alter.columns_str = source_columns;
    dummy_alter.alter_version = source_metadata_version;
    dummy_alter.create_time = time(nullptr);
    zookeeper->create(replica_path + "/queue/queue-", dummy_alter.toString(), zkutil::CreateMode::PersistentSequential);
    
    
    
}
void StorageReplicatedMergeTree::cloneReplicaIfNeeded(zkutil::ZooKeeperPtr zookeeper)
{
    Coordination::Stat is_lost_stat;
    bool is_new_replica = true;
    String res;
    if (zookeeper->tryGet(fs::path(replica_path) / "is_lost", res, &is_lost_stat))
    {
        if (res == "0")
            return;
        if (is_lost_stat.version)
            is_new_replica = false;
    }
    else
    {
        
        
        
        zookeeper->create(fs::path(replica_path) / "is_lost", "0", zkutil::CreateMode::Persistent);
        return;
    }