berkaysynnada commented on code in PR #5603:
URL: https://github.com/apache/arrow-datafusion/pull/5603#discussion_r1140406495
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datafusion/common/src/scalar.rs:
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@@ -563,46 +843,154 @@ macro_rules! get_sign {
};
}
+#[derive(Clone, Copy)]
+enum IntervalMode {
+ Milli,
+ Nano,
+}
+
+/// This function computes subtracts `rhs_ts` from `lhs_ts`, taking timezones
+/// into account when given. Units of the resulting interval is specified by
+/// the argument `mode`.
+/// The default behavior of Datafusion is the following:
+/// - When subtracting timestamps at seconds/milliseconds precision, the output
+/// interval will have the type [`IntervalDayTimeType`].
+/// - When subtracting timestamps at microseconds/nanoseconds precision, the
+/// output interval will have the type [`IntervalMonthDayNanoType`].
+fn ts_sub_to_interval(
+ lhs_ts: i64,
+ rhs_ts: i64,
+ lhs_tz: &Option<String>,
+ rhs_tz: &Option<String>,
+ mode: IntervalMode,
+) -> Result<ScalarValue, DataFusionError> {
+ let lhs_dt = with_timezone_to_naive_datetime(lhs_ts, lhs_tz, mode)?;
+ let rhs_dt = with_timezone_to_naive_datetime(rhs_ts, rhs_tz, mode)?;
+ let delta_secs = lhs_dt.signed_duration_since(rhs_dt);
+
+ match mode {
+ IntervalMode::Milli => {
+ let as_millisecs = delta_secs.num_milliseconds();
+ Ok(ScalarValue::IntervalDayTime(Some(
+ IntervalDayTimeType::make_value(
+ (as_millisecs / MILLISECS_IN_ONE_DAY) as i32,
+ (as_millisecs % MILLISECS_IN_ONE_DAY) as i32,
+ ),
+ )))
+ }
+ IntervalMode::Nano => {
+ let as_nanosecs = delta_secs.num_nanoseconds().ok_or_else(|| {
+ DataFusionError::Execution(String::from(
+ "Can not compute timestamp differences with nanosecond
precision",
+ ))
+ })?;
+ Ok(ScalarValue::IntervalMonthDayNano(Some(
+ IntervalMonthDayNanoType::make_value(
+ 0,
+ (as_nanosecs / NANOSECS_IN_ONE_DAY) as i32,
+ as_nanosecs % NANOSECS_IN_ONE_DAY,
+ ),
+ )))
+ }
+ }
+}
+
+/// This function creates the [`NaiveDateTime`] object corresponding to the
+/// given timestamp using the units (tick size) implied by argument `mode`.
+#[inline]
+fn with_timezone_to_naive_datetime(
Review Comment:
> TBC I don't think this blocks this PR, if one of the DF reviewers is happy
with it, it was just an idle suggestion as it would save reimplementing parsing
and timezone handling logic that already exists upstream, and ensures timezones
are handled consistently 😄
Thanks for the suggestion. I added the necessary dependencies and features
(arrow-array and chrono-tz), and now we can handle the timezones in the form of
the example you gave.
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