**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'
```
String replica_path;
        Int32 columns_version;
        UInt64 log_max_index;
        UInt64 log_pointer;
        UInt64 absolute_delay;
        UInt8 total_replicas;
        UInt8 active_replicas;
        
        String zookeeper_exception;
    };
    
    void getStatus(Status & res, bool with_zk_fields = true);
    using LogEntriesData = std::vector<ReplicatedMergeTreeLogEntryData>;
    void getQueue(LogEntriesData & res, String & replica_name);
    std::vector<PartMovesBetweenShardsOrchestrator::Entry> getPartMovesBetweenShardsEntries();
    
    time_t getAbsoluteDelay() const;
    
    
    
    void getReplicaDelays(time_t & out_absolute_delay, time_t & out_relative_delay);
    
    void enqueuePartForCheck(const String & part_name, time_t delay_to_check_seconds = 0)
    {
        part_check_thread.enqueuePart(part_name, delay_to_check_seconds);
    }
    CheckResults checkData(const ASTPtr & query, ContextPtr context) override;
    
    bool canUseAdaptiveGranularity() const override;
    int getMetadataVersion() const { return metadata_version; }