code: public static boolean isInFixedLengthPart(InternalType type) {
  		if (type instanceof DecimalType) {
  			return ((DecimalType) type).precision() <= DecimalType.MAX_COMPACT_PRECISION;
  		} else {
  			return MUTABLE_FIELD_TYPES.contains(type);
  		}
  	}
docs: If it is a fixed-length field, we can call this BinaryRow's setXX method for in-place updates.
  If it is variable-length field, can't use this method, because the underlying data is stored continuously.