**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 log_entries = zookeeper->getChildren(fs::path(zookeeper_path) / "log");
            if (!log_entries.empty())
            {
                const String & last_log_entry = *std::max_element(log_entries.begin(), log_entries.end());
                res.log_max_index = parse<UInt64>(last_log_entry.substr(strlen("log-")));
            }
            String log_pointer_str = zookeeper->get(fs::path(replica_path) / "log_pointer");
            res.log_pointer = log_pointer_str.empty() ? 0 : parse<UInt64>(log_pointer_str);
            auto all_replicas = zookeeper->getChildren(fs::path(zookeeper_path) / "replicas");
            res.total_replicas = all_replicas.size();
            for (const String & replica : all_replicas)
                if (zookeeper->exists(fs::path(zookeeper_path) / "replicas" / replica / "is_active"))
                    ++res.active_replicas;
        }
        catch (const Coordination::Exception &)
        {
            res.zookeeper_exception = getCurrentExceptionMessage(false);
        }
    }
}
void StorageReplicatedMergeTree::getQueue(LogEntriesData & res, String & replica_name_)
{
    replica_name_ = replica_name;
    queue.getEntries(res);
}
std::vector<PartMovesBetweenShardsOrchestrator::Entry> StorageReplicatedMergeTree::getPartMovesBetweenShardsEntries()
{
    return part_moves_between_shards_orchestrator.getEntries();
}
time_t StorageReplicatedMergeTree::getAbsoluteDelay() const