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 (!column.type->canBeUsedAsVersion())
                    throw Exception("The column " + version_column +
                        " cannot be used as a version column for storage " + storage +
                        " because it is of type " + column.type->getName() +
                        " (must be of an integer type or of type Date/DateTime/DateTime64)", ErrorCodes::BAD_TYPE_OF_FIELD);
                miss_column = false;
                break;
            }
        }
        if (miss_column)
            throw Exception("Version column " + version_column + " does not exist in table declaration.", ErrorCodes::NO_SUCH_COLUMN_IN_TABLE);
    };
    if (mode == MergingParams::Collapsing)
        check_sign_column(false, "CollapsingMergeTree");
    if (mode == MergingParams::Summing)
    {
        
        for (const auto & column_to_sum : columns_to_sum)
        {
            auto check_column_to_sum_exists = [& column_to_sum](const NameAndTypePair & name_and_type)
            {
                return column_to_sum == Nested::extractTableName(name_and_type.name);
            };
            if (columns.end() == std::find_if(columns.begin(), columns.end(), check_column_to_sum_exists))
                throw Exception(
                        "Column " + column_to_sum + " listed in columns to sum does not exist in table declaration.", ErrorCodes::NO_SUCH_COLUMN_IN_TABLE);
        }
        
        if (metadata.isPartitionKeyDefined())
        {