id Nullable(Int32), bool_col Nullable(UInt8), tinyint_col Nullable(Int32), smallint_col Nullable(Int32), int_col Nullable(Int32), bigint_col Nullable(Int64), float_col Nullable(Float32), double_col Nullable(Float64), date_string_col Nullable(String), string_col Nullable(String), timestamp_col Nullable(Int64)