appletreeisyellow commented on code in PR #9068:
URL: https://github.com/apache/arrow-datafusion/pull/9068#discussion_r1471364271
##########
datafusion/physical-expr/src/datetime_expressions.rs:
##########
@@ -564,8 +564,34 @@ fn _date_trunc_coarse_with_tz(
granularity: &str,
value: Option<DateTime<Tz>>,
) -> Result<Option<i64>> {
- let value = _date_trunc_coarse::<DateTime<Tz>>(granularity, value)?;
- Ok(value.and_then(|value| value.timestamp_nanos_opt()))
+ if let Some(value) = value {
+ let local = value.naive_local();
+ let truncated = _date_trunc_coarse::<NaiveDateTime>(granularity,
Some(local))?;
+ let truncated = truncated.map(|truncated| {
+ match truncated.and_local_timezone(value.timezone()) {
+ LocalResult::None => {
+ // It is impossible to truncate from a time that does
exist into one that doesn't.
+ panic!("date_trunc produced impossible time")
+ }
+ LocalResult::Single(datetime) => datetime,
+ LocalResult::Ambiguous(datetime1, datetime2) => {
+ // Because we are truncating from an equally or more
specific time
+ // the original time must have been within the ambiguous
local time
+ // period. Therefore the offset of one of these times
should match the
+ // offset of the original time.
+ if datetime1.offset().fix() == value.offset().fix() {
+ datetime1
+ } else {
+ datetime2
+ }
Review Comment:
Nice!
##########
datafusion/sqllogictest/test_files/timestamps.slt:
##########
@@ -1262,6 +1262,89 @@ SELECT DATE_TRUNC('day', arrow_cast(TIMESTAMP
'2023-08-03 14:38:50Z', 'Timestamp
2023-08-03T14:38:50
2023-08-03T14:38:50
+# date_trunc with data with timezones
+statement ok
+CREATE TABLE timestamp_strings(ts varchar)
+AS VALUES
+('2024-10-27 00:00:00'),
+('2024-10-27 00:30:00'),
+('2024-10-27 01:30:00'),
+('2024-10-27 02:00:00'), -- Daylight Savings Time happens here in Berlin
+('2024-10-27 02:30:00'),
+('2024-10-27 03:00:00'),
+('2024-10-27 03:30:00')
+;
+
+statement ok
+create view timestamp_utc as
+select
+ arrow_cast(ts, 'Timestamp(Nanosecond, Some("UTC"))') as ts
+from timestamp_strings;
+
+statement ok
+create view timestamp_berlin as
+select
+ arrow_cast(ts, 'Timestamp(Nanosecond, Some("Europe/Berlin"))') as ts
+from timestamp_utc; -- have to convert to utc prior to converting to berlin
+
+query PT
Review Comment:
@alamb What does `query PT` mean? Same question for `query PPPP`
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