**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'
```
{
    auto zookeeper = getZooKeeper();
    
    const String quorum_last_part_path = fs::path(zookeeper_path) / "quorum" / "last_part";
    
    while (true)
    {
        Coordination::Stat added_parts_stat;
        String old_added_parts = zookeeper->get(quorum_last_part_path, &added_parts_stat);
        ReplicatedMergeTreeQuorumAddedParts parts_with_quorum(format_version);
        if (!old_added_parts.empty())
            parts_with_quorum.fromString(old_added_parts);
        
        if (!parts_with_quorum.added_parts.count(partition_id))
        {
            
            break;
        }
        parts_with_quorum.added_parts.erase(partition_id);
        String new_added_parts = parts_with_quorum.toString();
        auto code = zookeeper->trySet(quorum_last_part_path, new_added_parts, added_parts_stat.version);
        if (code == Coordination::Error::ZOK)
        {
            break;
        }
        else if (code == Coordination::Error::ZNONODE)
        {
            
            break;