fix the case in Australia/Lord_Howe where the shift is 30 min

Signed-off-by: Runji Wang <[email protected]>

e2e_test/batch/functions/issue_12072.slt.part

@@ -123,7 +123,6 @@ select date_trunc('day', v, 'America/Havana') from t order by id;
 # (F) jump-forward from day boundary, making it invalid
 # Here `2023-09-02 23:59:59-04:00` is followed by `2023-09-03 01:00:00-03:00`.
 # There is no `2023-09-03 00:00:00-04:00` or `2023-09-03 00:00:00-03:00`.
-# PostgreSQL returns `2023-09-03 01:00:00-03:00` but it is hard using `chrono` crate.
 
 query T
 select date_trunc('day', '2023-09-03 12:00:00Z'::timestamptz, 'America/Santiago');

src/expr/impl/src/scalar/timestamptz.rs

@@ -45,24 +45,27 @@ pub fn f64_sec_to_timestamptz(elem: F64) -> Result<Timestamptz> {
 pub fn timestamp_at_time_zone(input: Timestamp, time_zone: &str) -> Result<Timestamptz> {
     let time_zone = Timestamptz::lookup_time_zone(time_zone).map_err(time_zone_err)?;
     // https://www.postgresql.org/docs/current/datetime-invalid-input.html
-    // Special cases:
-    // * invalid time during daylight forward
-    //   * use UTC offset before the transition
-    // * ambiguous time during daylight backward
-    //   * use UTC offset after the transition
     let instant_local = match input.0.and_local_timezone(time_zone) {
         LocalResult::Single(t) => t,
-        LocalResult::None => (input.0 + chrono::Duration::hours(1))
-            .and_local_timezone(time_zone)
-            .latest()
-            .ok_or_else(|| ExprError::InvalidParam {
-                name: "local timestamp",
-                reason: format!(
-                    "fail to interpret local timestamp \"{}\" in time zone \"{}\"",
-                    input, time_zone
-                )
-                .into(),
-            })?,
+        // invalid time during daylight forward, use UTC offset before the transition
+        // we minus 3 hours in naive time first, do the timezone conversion, and add 3 hours back in the UTC timeline.
+        // This assumes jump forwards are less than 3 hours and there is a single change within this 3-hour window.
+        // see <https://github.com/risingwavelabs/risingwave/pull/15670#discussion_r1524211006>
+        LocalResult::None => {
+            (input.0 - chrono::Duration::hours(3))
+                .and_local_timezone(time_zone)
+                .latest()
+                .ok_or_else(|| ExprError::InvalidParam {
+                    name: "local timestamp",
+                    reason: format!(
+                        "fail to interpret local timestamp \"{}\" in time zone \"{}\"",
+                        input, time_zone
+                    )
+                    .into(),
+                })?
+                + chrono::Duration::hours(3)
+        }
+        // ambiguous time during daylight backward, use UTC offset after the transition
         LocalResult::Ambiguous(_, latest) => latest,
     };
     let usec = instant_local.timestamp_micros();
@@ -237,10 +240,15 @@ mod tests {
     #[test]
     #[rustfmt::skip]
     fn test_time_zone_conversion_daylight_forward() {
+        // [02:00. 03:00) are invalid
         test("2022-03-13 02:00:00", "US/Pacific", "2022-03-13 10:00:00+00:00");
-        test("2022-03-13 02:59:00", "US/Pacific", "2022-03-13 10:59:00+00:00");
+        test("2022-03-13 03:00:00", "US/Pacific", "2022-03-13 10:00:00+00:00");
+        // [02:00. 03:00) are invalid
         test("2022-03-27 02:00:00", "europe/zurich", "2022-03-27 01:00:00+00:00");
-        test("2022-03-27 02:59:00", "europe/zurich", "2022-03-27 01:59:00+00:00");
+        test("2022-03-27 03:00:00", "europe/zurich", "2022-03-27 01:00:00+00:00");
+        // [02:00. 02:30) are invalid
+        test("2023-10-01 02:00:00", "Australia/Lord_Howe", "2023-09-30 15:30:00+00:00");
+        test("2023-10-01 02:30:00", "Australia/Lord_Howe", "2023-09-30 15:30:00+00:00");
 
         #[track_caller]
         fn test(local: &str, zone: &str, instant: &str) {