**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;
    }
    auto metadata_snapshot = getInMemoryMetadataPtr();
    
    
    if (attach && !current_zookeeper->exists(replica_path))
    {
        LOG_WARNING(log, "No metadata in ZooKeeper for {}: table will be in readonly mode", replica_path);
        is_readonly = true;
        has_metadata_in_zookeeper = false;
        return;
    }
    if (!attach)
    {
        if (!getDataParts().empty())
            throw Exception("Data directory for table already contains data parts"
                " - probably it was unclean DROP table or manual intervention."
                " You must either clear directory by hand or use ATTACH TABLE"
                " instead of CREATE TABLE if you need to use that parts.", ErrorCodes::INCORRECT_DATA);
        try
        {
            bool is_first_replica = createTableIfNotExists(metadata_snapshot);
            try
            {
                
                
                
                
                other_replicas_fixed_granularity = checkFixedGranularityInZookeeper();
                checkTableStructure(zookeeper_path, metadata_snapshot);