Function DoTrunc

be/src/exprs/udf-builtins.cc:283–385

Used by both TRUNC and DATE_TRUNC functions to perform the truncation

// Used by both TRUNC and DATE_TRUNC functions to perform the truncation
TimestampVal DoTrunc(
    const TimestampValue& ts, TruncUnit trunc_unit, FunctionContext* ctx) {
  const date& orig_date = ts.date();
  const time_duration& orig_time = ts.time();
  TimestampValue ret;
  TimestampVal ret_val;

  // check for invalid or malformed timestamps
  switch (trunc_unit) {
    case TruncUnit::MILLENNIUM:
      // for millenium <= 2000 year value goes to 1001 (outside the supported range)
      if (orig_date.is_special()) return TimestampVal::null();
      if (orig_date.year() <= 2000) return TimestampVal::null();
      break;
    case TruncUnit::CENTURY:
      // for century <= 1400 year value goes to 1301 (outside the supported range)
      if (orig_date.is_special()) return TimestampVal::null();
      if (orig_date.year() <= 1400) return TimestampVal::null();
      break;
    case TruncUnit::WEEK:
      // anything less than 1400-1-6 we have to move to year 1399
      if (orig_date.is_special()) return TimestampVal::null();
      if (orig_date < date(1400, 1, 6)) return TimestampVal::null();
      break;
    case TruncUnit::YEAR:
    case TruncUnit::QUARTER:
    case TruncUnit::MONTH:
    case TruncUnit::WW:
    case TruncUnit::W:
    case TruncUnit::DAY:
    case TruncUnit::DAY_OF_WEEK:
    case TruncUnit::DECADE:
      if (orig_date.is_special()) return TimestampVal::null();
      break;
    case TruncUnit::HOUR:
    case TruncUnit::MINUTE:
    case TruncUnit::SECOND:
    case TruncUnit::MILLISECONDS:
    case TruncUnit::MICROSECONDS:
      if (orig_time.is_special()) return TimestampVal::null();
      break;
    case TruncUnit::UNIT_INVALID:
      DCHECK(false);
  }

  switch(trunc_unit) {
    case TruncUnit::YEAR:
      ret = TruncYear(orig_date);
      break;
    case TruncUnit::QUARTER:
      ret = TruncQuarter(orig_date);
      break;
    case TruncUnit::MONTH:
      ret = TruncMonth(orig_date);
      break;
    case TruncUnit::WW:
      ret = TruncWW(orig_date);
      break;