**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'
```
size_t source_log_pointer = get_log_pointer.data.empty() ? 0 : parse<UInt64>(get_log_pointer.data);
        assert(source_log_pointer <= max_log_entry);
        size_t replica_queue_lag = max_log_entry - source_log_pointer;
        size_t replica_queue_size = get_queue.stat.numChildren;
        size_t replication_lag = replica_queue_lag + replica_queue_size;
        LOG_INFO(log, "Replica {} has log pointer '{}', approximate {} queue lag and {} queue size",
                 source_replica_name, get_log_pointer.data, replica_queue_lag, replica_queue_size);
        if (replication_lag < min_replication_lag)
        {
            source_replica = source_replica_name;
            source_is_lost_stat = get_is_lost.stat;
            min_replication_lag = replication_lag;
        }
    }
    if (source_replica.empty())
        throw Exception("All replicas are lost", ErrorCodes::ALL_REPLICAS_LOST);
    if (is_new_replica)
        LOG_INFO(log, "Will mimic {}", source_replica);
    else
        LOG_WARNING(log, "Will mimic {}", source_replica);
    
    zookeeper->removeChildren(fs::path(replica_path) / "queue");
    queue.clear();
    
    cloneReplica(source_replica, source_is_lost_stat, zookeeper);
    
    
    zookeeper->set(fs::path(replica_path) / "is_lost", "0");
}
void StorageReplicatedMergeTree::queueUpdatingTask()