**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'
```
*/
    Int64 right;
    Int64 mutation_version;
    {
        auto zookeeper = getZooKeeper();
        delimiting_block_lock = allocateBlockNumber(partition_id, zookeeper);
        right = delimiting_block_lock->getNumber();
        
        
        
        mutation_version = MergeTreePartInfo::MAX_BLOCK_NUMBER;
    }
    if (for_replace_range)
    {
        
        
        
        
        part_info = MergeTreePartInfo(partition_id, left, right, MergeTreePartInfo::MAX_LEVEL, mutation_version);
        return right != 0;
    }
    
    if (right == 0)
        return false;
    --right;
    
    part_info = MergeTreePartInfo(partition_id, left, right, MergeTreePartInfo::MAX_LEVEL, mutation_version);
    return true;
}
void StorageReplicatedMergeTree::restoreMetadataInZooKeeper()