**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'
```
};
    try
    {
        part = merger_mutator.mergePartsToTemporaryPart(
            future_merged_part,
            metadata_snapshot,
            *merge_entry,
            table_lock,
            entry.create_time,
            getContext(),
            reserved_space,
            entry.deduplicate,
            entry.deduplicate_by_columns,
            merging_params);
        merger_mutator.renameMergedTemporaryPart(part, parts, &transaction);
        try
        {
            checkPartChecksumsAndCommit(transaction, part);
        }
        catch (const Exception & e)
        {
            if (MergeTreeDataPartChecksums::isBadChecksumsErrorCode(e.code()))
            {
                transaction.rollback();
                ProfileEvents::increment(ProfileEvents::DataAfterMergeDiffersFromReplica);
                LOG_ERROR(log,
                    "{}. Data after merge is not byte-identical to data on another replicas. There could be several"
                    " reasons: 1. Using newer version of compression library after server update. 2. Using another"
                    " compression method. 3. Non-deterministic compression algorithm (highly unlikely). 4."
                    " Non-deterministic merge algorithm due to logical error in code. 5. Data corruption in memory due"