I am reading clickhouse mutation code. In StorageMergeTree->selectPartsToMutate() function, there is a check 
`if (current_ast_elements + commands_size >= max_ast_elements)
                break;`

I think if there are many mutations then the check result will be true, so that it will skip the remaining mutations.
But the new part's mutation is set to the last one in mutation map, and it does not apply the remaining mutations actually.
`new_part_info.mutation = current_mutations_by_version.rbegin()->first;`

Then the new part will miss the remaining mutations in future mutation job.

I think it's wrong here. Am I right?

If it is right, I will submit a PR 

{
    assertNotReadonly();
    if (!is_leader)
        throw Exception("DROP PART cannot be done on this replica because it is not a leader", ErrorCodes::NOT_A_LEADER);
    zkutil::ZooKeeperPtr zookeeper = getZooKeeper();
    LogEntry entry;
    dropPartImpl(zookeeper, part_name, entry, detach,  true);
    waitForLogEntryToBeProcessedIfNecessary(entry, query_context);
}
void StorageReplicatedMergeTree::dropPartition(const ASTPtr & partition, bool detach, ContextPtr query_context)
{
    assertNotReadonly();
    if (!is_leader)
        throw Exception("DROP PARTITION cannot be done on this replica because it is not a leader", ErrorCodes::NOT_A_LEADER);
    zkutil::ZooKeeperPtr zookeeper = getZooKeeper();
    LogEntry entry;
    String partition_id = getPartitionIDFromQuery(partition, query_context);
    bool did_drop = dropAllPartsInPartition(*zookeeper, partition_id, entry, query_context, detach);
    if (did_drop)
    {
        waitForLogEntryToBeProcessedIfNecessary(entry, query_context);
        cleanLastPartNode(partition_id);
    }
}
void StorageReplicatedMergeTree::truncate(