protected void truncDate(LongColumnVector inV, BytesColumnVector outV, int i) {
    date = Date.ofEpochMilli(inV.vector[i]);
    processDate(outV, i, date);
  }
Vectorized implementation of trunc(date, fmt) function date timestamp input
ql/src/java/org/apache/hadoop/hive/ql/exec/vector/expressions/TruncDateFromDate.java