`CREATE TABLE test (x Int32, y Int32, s String, PRIMARY KEY (x, y)) ENGINE = MergeTree;`
should be equivalent to
`CREATE TABLE test (x Int32, y Int32, s String) ENGINE = MergeTree PRIMARY KEY (x, y);`
default:
            break;
        case MergeTreeData::MergingParams::Summing:
            add_optional_param("list of columns to sum");
            break;
        case MergeTreeData::MergingParams::Replacing:
            add_optional_param("version");
            break;
        case MergeTreeData::MergingParams::Collapsing:
            add_mandatory_param("sign column");
            break;
        case MergeTreeData::MergingParams::Graphite:
            add_mandatory_param("'config_element_for_graphite_schema'");
            break;
        case MergeTreeData::MergingParams::VersionedCollapsing: {
            add_mandatory_param("sign column");
            add_mandatory_param("version");
            break;
        }
    }
    ASTs & engine_args = args.engine_args;
    size_t arg_num = 0;
    size_t arg_cnt = engine_args.size();
    if (arg_cnt < min_num_params || arg_cnt > max_num_params)
    {
        String msg;
        if (is_extended_storage_def)
            msg += "With extended storage definition syntax storage " + args.engine_name + " requires ";
        else
            msg += "Storage " + args.engine_name + " requires ";