**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'
```
bool tryRemovePartsFromZooKeeperWithRetries(DataPartsVector & parts, size_t max_retries = 5);
    
    void removePartAndEnqueueFetch(const String & part_name);
    
    /** Execute the action from the queue. Throws an exception if something is wrong.
      * Returns whether or not it succeeds. If it did not work, write it to the end of the queue.
      */
    bool executeLogEntry(LogEntry & entry);
    
    
    MutableDataPartPtr attachPartHelperFoundValidPart(const LogEntry& entry) const;
    void executeDropRange(const LogEntry & entry);
    
    bool tryExecuteMerge(const LogEntry & entry);
    
    
    
    bool executeMetadataAlter(const LogEntry & entry);
    
    
    bool tryExecutePartMutation(const LogEntry & entry);
    
    
    
    
    bool executeFetch(LogEntry & entry);
    bool executeReplaceRange(const LogEntry & entry);
    void executeClonePartFromShard(const LogEntry & entry);
    /** Updates the queue.
      */