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 

{
    if (metadata.sampling_key.column_names.empty())
        throw Exception("There are no columns in sampling expression", ErrorCodes::INCORRECT_QUERY);
    const auto & pk_sample_block = metadata.getPrimaryKey().sample_block;
    if (!pk_sample_block.has(metadata.sampling_key.column_names[0]) && !allow_sampling_expression_not_in_primary_key)
        throw Exception("Sampling expression must be present in the primary key", ErrorCodes::BAD_ARGUMENTS);
    if (!check_sample_column_is_correct)
        return;
    const auto & sampling_key = metadata.getSamplingKey();
    DataTypePtr sampling_column_type = sampling_key.data_types[0];
    bool is_correct_sample_condition = false;
    if (sampling_key.data_types.size() == 1)
    {
        if (typeid_cast<const DataTypeUInt64 *>(sampling_column_type.get()))
            is_correct_sample_condition = true;
        else if (typeid_cast<const DataTypeUInt32 *>(sampling_column_type.get()))
            is_correct_sample_condition = true;
        else if (typeid_cast<const DataTypeUInt16 *>(sampling_column_type.get()))
            is_correct_sample_condition = true;
        else if (typeid_cast<const DataTypeUInt8 *>(sampling_column_type.get()))
            is_correct_sample_condition = true;
    }
    if (!is_correct_sample_condition)
        throw Exception(
            "Invalid sampling column type in storage parameters: " + sampling_column_type->getName()
            + ". Must be one unsigned integer type",
            ErrorCodes::ILLEGAL_TYPE_OF_COLUMN_FOR_FILTER);
}
inline UInt64 time_in_microseconds(std::chrono::time_point<std::chrono::system_clock> timepoint)