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 

const StorageInMemoryMetadata & new_metadata, const StorageInMemoryMetadata & old_metadata, bool attach) const
{
    if (!new_metadata.sorting_key.definition_ast)
        throw Exception("ORDER BY cannot be empty", ErrorCodes::BAD_ARGUMENTS);
    KeyDescription new_sorting_key = new_metadata.sorting_key;
    KeyDescription new_primary_key = new_metadata.primary_key;
    size_t sorting_key_size = new_sorting_key.column_names.size();
    size_t primary_key_size = new_primary_key.column_names.size();
    if (primary_key_size > sorting_key_size)
        throw Exception("Primary key must be a prefix of the sorting key, but its length: "
            + toString(primary_key_size) + " is greater than the sorting key length: " + toString(sorting_key_size),
            ErrorCodes::BAD_ARGUMENTS);
    NameSet primary_key_columns_set;
    for (size_t i = 0; i < sorting_key_size; ++i)
    {
        const String & sorting_key_column = new_sorting_key.column_names[i];
        if (i < primary_key_size)
        {
            const String & pk_column = new_primary_key.column_names[i];
            if (pk_column != sorting_key_column)
                throw Exception("Primary key must be a prefix of the sorting key, but the column in the position "
                    + toString(i) + " is " + sorting_key_column +", not " + pk_column,
                    ErrorCodes::BAD_ARGUMENTS);
            if (!primary_key_columns_set.emplace(pk_column).second)
                throw Exception("Primary key contains duplicate columns", ErrorCodes::BAD_ARGUMENTS);
        }
    }
    auto all_columns = new_metadata.columns.getAllPhysical();