**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'
```
else
        throw Exception("Logical error: unexpected name of log node: " + entry.znode_name, ErrorCodes::LOGICAL_ERROR);
    LOG_DEBUG(log, "Looking for node corresponding to {} in {} queue", log_node_name, replica);
    /** Second - find the corresponding entry in the queue of the specified replica.
      * Its number may not match the `log` node. Therefore, we search by comparing the content.
      */
    Strings queue_entries = getZooKeeper()->getChildren(fs::path(table_zookeeper_path) / "replicas" / replica / "queue");
    String queue_entry_to_wait_for;
    for (const String & entry_name : queue_entries)
    {
        String queue_entry_str;
        bool exists = getZooKeeper()->tryGet(fs::path(table_zookeeper_path) / "replicas" / replica / "queue" / entry_name, queue_entry_str);
        if (exists && queue_entry_str == entry_str)
        {
            queue_entry_to_wait_for = entry_name;
            break;
        }
    }
    
    if (queue_entry_to_wait_for.empty())
    {
        LOG_DEBUG(log, "No corresponding node found. Assuming it has been already processed. Found {} nodes", queue_entries.size());
        return true;
    }
    LOG_DEBUG(log, "Waiting for {} to disappear from {} queue", queue_entry_to_wait_for, replica);
    
    String path_to_wait_on = fs::path(table_zookeeper_path) / "replicas" / replica / "queue" / queue_entry_to_wait_for;
    return getZooKeeper()->waitForDisappear(path_to_wait_on, stop_waiting);
}
bool StorageReplicatedMergeTree::waitForReplicaToProcessLogEntry(