**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'
```
QueryPlan & query_plan,
    const Names & column_names,
    const StorageMetadataPtr & metadata_snapshot,
    SelectQueryInfo & query_info,
    ContextPtr local_context,
    QueryProcessingStage::Enum processed_stage,
    const size_t max_block_size,
    const unsigned num_streams)
{
    /** The `select_sequential_consistency` setting has two meanings:
    * 1. To throw an exception if on a replica there are not all parts which have been written down on quorum of remaining replicas.
    * 2. Do not read parts that have not yet been written to the quorum of the replicas.
    * For this you have to synchronously go to ZooKeeper.
    */
    if (local_context->getSettingsRef().select_sequential_consistency)
    {
        auto max_added_blocks = std::make_shared<ReplicatedMergeTreeQuorumAddedParts::PartitionIdToMaxBlock>(getMaxAddedBlocks());
        if (auto plan = reader.read(
                column_names, metadata_snapshot, query_info, local_context, max_block_size, num_streams, processed_stage, std::move(max_added_blocks)))
            query_plan = std::move(*plan);
        return;
    }
    if (auto plan = reader.read(column_names, metadata_snapshot, query_info, local_context, max_block_size, num_streams, processed_stage))
        query_plan = std::move(*plan);
}
Pipe StorageReplicatedMergeTree::read(