@Override
  protected void func(LongColumnVector outV, TimestampColumnVector inV, int i) {

    outV.vector[i] = DateWritableV2.millisToDays(inV.getTime(i));
  }
To be used to cast timestamp to decimal.
ql/src/java/org/apache/hadoop/hive/ql/exec/vector/expressions/CastTimestampToDate.java