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