**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'
```
{
    return queue.getMutationsStatus();
}
CancellationCode StorageReplicatedMergeTree::killMutation(const String & mutation_id)
{
    assertNotReadonly();
    zkutil::ZooKeeperPtr zookeeper = getZooKeeper();
    LOG_TRACE(log, "Killing mutation {}", mutation_id);
    auto mutation_entry = queue.removeMutation(zookeeper, mutation_id);
    if (!mutation_entry)
        return CancellationCode::NotFound;
    
    
    
    for (const auto & pair : mutation_entry->block_numbers)
    {
        const String & partition_id = pair.first;
        Int64 block_number = pair.second;
        getContext()->getMergeList().cancelPartMutations(getStorageID(), partition_id, block_number);
    }
    return CancellationCode::CancelSent;
}
void StorageReplicatedMergeTree::clearOldPartsAndRemoveFromZK()