**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'
```
part_names.emplace_back(part->name);
            
            
            
            
            
            
            
            
            throw Exception(ErrorCodes::INCORRECT_DATA, "Tried to create empty part {}, but it replaces existing parts {}.", lost_part_name, fmt::join(part_names, ", "));
        }
        while (true)
        {
            Coordination::Requests ops;
            Coordination::Stat replicas_stat;
            auto replicas_path = fs::path(zookeeper_path) / "replicas";
            Strings replicas = zookeeper->getChildren(replicas_path, &replicas_stat);
            
            ops.emplace_back(zkutil::makeCheckRequest(replicas_path, replicas_stat.version));
            for (const String & replica : replicas)
            {
                String current_part_path = fs::path(zookeeper_path) / "replicas" / replica / "parts" / lost_part_name;
                
                if (!zookeeper->exists(current_part_path))
                {
                    ops.emplace_back(zkutil::makeCreateRequest(current_part_path, "", zkutil::CreateMode::Persistent));
                    ops.emplace_back(zkutil::makeRemoveRequest(current_part_path, -1));
                }
                else
                {