**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'
```
const ReplicatedMergeTreeLogEntryData & entry, bool wait_for_non_active)
{
    return waitForAllTableReplicasToProcessLogEntry(zookeeper_path, entry, wait_for_non_active);
}
bool StorageReplicatedMergeTree::waitForTableReplicaToProcessLogEntry(
    const String & table_zookeeper_path, const String & replica, const ReplicatedMergeTreeLogEntryData & entry, bool wait_for_non_active)
{
    String entry_str = entry.toString();
    String log_node_name;
    /** Wait for entries from `log` directory (a common log, from where replicas copy entries to their queue) to be processed.
      *
      * The problem is that the numbers (`sequential` node) of the queue elements in `log` and in `queue` do not match.
      * (And the numbers of the same log element for different replicas do not match in the `queue`.)
      */
    /** First, you need to wait until replica takes `queue` element from the `log` to its queue,
      *  if it has not been done already (see the `pullLogsToQueue` function).
      *
      * To do this, check its node `log_pointer` - the maximum number of the element taken from `log` + 1.