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 (columns_alter_type_metadata_only.count(command.column_name))
                {
                    auto it = old_types.find(command.column_name);
                    assert(it != old_types.end());
                    if (!isSafeForKeyConversion(it->second, command.data_type.get()))
                        throw Exception("ALTER of key column " + backQuoteIfNeed(command.column_name) + " from type "
                                    + it->second->getName() + " to type " + command.data_type->getName()
                                    + " is not safe because it can change the representation of primary key",
                            ErrorCodes::ALTER_OF_COLUMN_IS_FORBIDDEN);
                }
                if (old_metadata.getColumns().has(command.column_name))
                {
                    columns_to_check_conversion.push_back(
                        new_metadata.getColumns().getPhysical(command.column_name));
                }
            }
        }
    }
    checkProperties(new_metadata, old_metadata);
    checkTTLExpressions(new_metadata, old_metadata);
    if (!columns_to_check_conversion.empty())
    {
        auto old_header = old_metadata.getSampleBlock();
        performRequiredConversions(old_header, columns_to_check_conversion, getContext());
    }
    if (old_metadata.hasSettingsChanges())
    {
        const auto current_changes = old_metadata.getSettingsChanges()->as<const ASTSetQuery &>().changes;
        const auto & new_changes = new_metadata.settings_changes->as<const ASTSetQuery &>().changes;
        for (const auto & changed_setting : new_changes)