@Override
  protected void assign(BytesColumnVector outV, int i, byte[] bytes, int offset, int length) {
    StringExpr.truncate(outV, i, bytes, offset, length, maxLength);
  }
To support vectorized cast of decimal to string.
ql/src/java/org/apache/hadoop/hive/ql/exec/vector/expressions/CastDecimalToVarChar.java