appletreeisyellow commented on code in PR #11347: URL: https://github.com/apache/datafusion/pull/11347#discussion_r1671322442
########## datafusion/functions/src/datetime/to_local_time.rs: ########## @@ -0,0 +1,601 @@ +// Licensed to the Apache Software Foundation (ASF) under one +// or more contributor license agreements. See the NOTICE file +// distributed with this work for additional information +// regarding copyright ownership. The ASF licenses this file +// to you under the Apache License, Version 2.0 (the +// "License"); you may not use this file except in compliance +// with the License. You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, +// software distributed under the License is distributed on an +// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY +// KIND, either express or implied. See the License for the +// specific language governing permissions and limitations +// under the License. + +use std::any::Any; +use std::ops::Add; +use std::sync::Arc; + +use arrow::array::timezone::Tz; +use arrow::array::{ArrayRef, PrimitiveArray}; +use arrow::datatypes::DataType::Timestamp; +use arrow::datatypes::{ + ArrowTimestampType, DataType, TimestampMicrosecondType, TimestampMillisecondType, + TimestampNanosecondType, TimestampSecondType, +}; +use arrow::datatypes::{ + TimeUnit, + TimeUnit::{Microsecond, Millisecond, Nanosecond, Second}, +}; + +use chrono::{Offset, TimeDelta, TimeZone, Utc}; +use datafusion_common::cast::as_primitive_array; +use datafusion_common::{exec_err, Result, ScalarValue}; +use datafusion_expr::TypeSignature::Exact; +use datafusion_expr::{ + ColumnarValue, ScalarUDFImpl, Signature, Volatility, TIMEZONE_WILDCARD, +}; + +/// A UDF function that converts a timezone-aware timestamp to local time (with no offset or +/// timezone information). In other words, this function strips off the timezone from the timestamp, +/// while keep the display value of the timestamp the same. +/// +/// # Example 1 +/// +/// ``` +/// # use datafusion_common::ScalarValue; +/// # use datafusion_expr::ColumnarValue; +/// # use datafusion_functions::datetime::to_local_time::ToLocalTimeFunc; +/// # use datafusion_expr::ScalarUDFImpl; +/// +/// // 2019-03-31 01:00:00 +01:00 +/// let res = ToLocalTimeFunc::new() +/// .invoke(&[ColumnarValue::Scalar(ScalarValue::TimestampSecond( +/// Some(1_553_990_400), +/// Some("Europe/Brussels".into()), +/// ))]) +/// .unwrap(); +/// +/// // 2019-03-31 01:00:00 <-- this timestamp no longer has +01:00 offset +/// let expected = ScalarValue::TimestampSecond(Some(1_553_994_000), None); +/// +/// match res { +/// ColumnarValue::Scalar(res) => { +/// assert_eq!(res, expected); +/// } +/// _ => panic!("unexpected return type"), +/// } +/// ``` +/// +/// # Example 2 +/// +/// ``` +/// # use datafusion_common::ScalarValue; +/// # use datafusion_expr::ColumnarValue; +/// # use chrono::NaiveDateTime; +/// # use datafusion_functions::datetime::to_local_time::ToLocalTimeFunc; +/// # use datafusion_expr::ScalarUDFImpl; +/// +/// let timestamp_str = "2020-03-31T13:40:00"; +/// let timezone_str = "America/New_York"; +/// let tz: arrow::array::timezone::Tz = +/// timezone_str.parse().expect("Invalid timezone"); +/// +/// let timestamp = timestamp_str +/// .parse::<NaiveDateTime>() +/// .unwrap() +/// .and_local_timezone(tz) // this is in a local timezone +/// .unwrap() +/// .timestamp_nanos_opt() +/// .unwrap(); +/// +/// let expected_timestamp = timestamp_str +/// .parse::<NaiveDateTime>() +/// .unwrap() +/// .and_utc() // this is in UTC +/// .timestamp_nanos_opt() +/// .unwrap(); +/// +/// let input = +/// ScalarValue::TimestampNanosecond(Some(timestamp), Some(timezone_str.into())); +/// let res = ToLocalTimeFunc::new() +/// .invoke(&[ColumnarValue::Scalar(input)]) +/// .unwrap(); +/// let expected = ScalarValue::TimestampNanosecond(Some(expected_timestamp), None); +/// match res { +/// ColumnarValue::Scalar(res) => { +/// assert_eq!(res, expected); +/// } +/// _ => panic!("unexpected return type"), +/// } +/// ``` +#[derive(Debug)] +pub struct ToLocalTimeFunc { + signature: Signature, +} + +impl Default for ToLocalTimeFunc { + fn default() -> Self { + Self::new() + } +} + +impl ToLocalTimeFunc { + pub fn new() -> Self { + let base_sig = |array_type: TimeUnit| { + vec![ + Exact(vec![Timestamp(array_type, None)]), + Exact(vec![Timestamp(array_type, Some(TIMEZONE_WILDCARD.into()))]), + ] + }; + + let full_sig = [Nanosecond, Microsecond, Millisecond, Second] + .into_iter() + .map(base_sig) + .collect::<Vec<_>>() + .concat(); + + Self { + signature: Signature::one_of(full_sig, Volatility::Immutable), + } + } + + fn to_local_time(&self, args: &[ColumnarValue]) -> Result<ColumnarValue> { + if args.len() != 1 { + return exec_err!( + "to_local_time function requires 1 argument, got {}", + args.len() + ); + } + + let time_value = args[0].clone(); + let arg_type = time_value.data_type(); + match arg_type { + DataType::Timestamp(_, None) => { + // if no timezone specificed, just return the input + Ok(time_value.clone()) + } + // if has timezone, adjust the underlying time value. the current time value + // is stored as i64 in UTC, even though the timezone may not be in UTC, so + // we need to adjust the time value to the local time. see [`adjust_to_local_time`] + // for more details. + // + // Then remove the timezone in return type, i.e. return None + DataType::Timestamp(_, Some(_)) => match time_value { + ColumnarValue::Scalar(ScalarValue::TimestampNanosecond( + Some(ts), + Some(tz), + )) => { + let adjusted_ts = + adjust_to_local_time::<TimestampNanosecondType>(ts, &tz); + Ok(ColumnarValue::Scalar(ScalarValue::TimestampNanosecond( + Some(adjusted_ts), + None, + ))) + } + ColumnarValue::Scalar(ScalarValue::TimestampMicrosecond( + Some(ts), + Some(tz), + )) => { + let adjusted_ts = + adjust_to_local_time::<TimestampMicrosecondType>(ts, &tz); + Ok(ColumnarValue::Scalar(ScalarValue::TimestampMicrosecond( + Some(adjusted_ts), + None, + ))) + } + ColumnarValue::Scalar(ScalarValue::TimestampMillisecond( + Some(ts), + Some(tz), + )) => { + let adjusted_ts = + adjust_to_local_time::<TimestampMillisecondType>(ts, &tz); + Ok(ColumnarValue::Scalar(ScalarValue::TimestampMillisecond( + Some(adjusted_ts), + None, + ))) + } + ColumnarValue::Scalar(ScalarValue::TimestampSecond( + Some(ts), + Some(tz), + )) => { + let adjusted_ts = + adjust_to_local_time::<TimestampSecondType>(ts, &tz); + Ok(ColumnarValue::Scalar(ScalarValue::TimestampSecond( + Some(adjusted_ts), + None, + ))) + } + ColumnarValue::Array(array) => { + fn transform_array<T>( + array: &ArrayRef, + tz: &str, + ) -> Result<ColumnarValue> + where + T: ArrowTimestampType, + { + let array = as_primitive_array::<T>(array)?; + let array: PrimitiveArray<T> = + array.unary(|ts| adjust_to_local_time::<T>(ts, tz)); + + Ok(ColumnarValue::Array(Arc::new(array))) + } + + match array.data_type() { + Timestamp(_, None) => { + // if no timezone specificed, just return the input + Ok(ColumnarValue::Array(Arc::new(array))) + } + Timestamp(Nanosecond, Some(tz)) => { + transform_array::<TimestampNanosecondType>(&array, tz) + } + Timestamp(Microsecond, Some(tz)) => { + transform_array::<TimestampMicrosecondType>(&array, tz) + } + Timestamp(Millisecond, Some(tz)) => { + transform_array::<TimestampMillisecondType>(&array, tz) + } + Timestamp(Second, Some(tz)) => { + transform_array::<TimestampSecondType>(&array, tz) + } + _ => { + exec_err!("to_local_time function requires timestamp argument in array, got {:?}", array.data_type()) + } + } + } + _ => { + exec_err!( + "to_local_time function requires timestamp argument, got {:?}", + time_value.data_type() + ) + } + }, + _ => { + exec_err!( + "to_local_time function requires timestamp argument, got {:?}", + arg_type + ) + } + } + } +} + +/// This function converts a timestamp with a timezone to a timestamp without a timezone. +/// The display value of the adjusted timestamp remain the same, but the underlying timestamp +/// representation is adjusted according to the relative timezone offset to UTC. +/// +/// This function uses chrono to handle daylight saving time changes. +/// +/// For example, +/// +/// ```text +/// '2019-03-31T01:00:00Z'::timestamp at time zone 'Europe/Brussels' +/// ``` +/// +/// is displayed as follows in datafusion-cli: +/// +/// ```text +/// 2019-03-31T01:00:00+01:00 +/// ``` +/// +/// and is represented in DataFusion as: +/// +/// ```text +/// TimestampNanosecond(Some(1_553_990_400_000_000_000), Some("Europe/Brussels")) +/// ``` +/// +/// To strip off the timezone while keeping the display value the same, we need to +/// adjust the underlying timestamp with the timezone offset value using `adjust_to_local_time()` +/// +/// ```text +/// adjust_to_local_time(1_553_990_400_000_000_000, "Europe/Brussels") --> 1_553_994_000_000_000_000 +/// ``` +/// +/// The difference between `1_553_990_400_000_000_000` and `1_553_994_000_000_000_000` is +/// `3600_000_000_000` ns, which corresponds to 1 hour. This matches with the timezone +/// offset for "Europe/Brussels". Consequently, DataFusion can represent the timestamp in +/// local time (with no offset or timezone information) as +/// +/// ```text +/// TimestampNanosecond(Some(1_553_994_000_000_000_000), None) +/// ``` +/// +/// which is displayed as follows in datafusion-cli: +/// +/// ```text +/// 2019-03-31T01:00:00 +/// ``` +fn adjust_to_local_time<T: ArrowTimestampType>(ts: i64, timezone: &str) -> i64 { + let date_time = match T::UNIT { + Nanosecond => Utc.timestamp_nanos(ts), + Microsecond => Utc.timestamp_micros(ts).unwrap(), // TODO chunchun: replace unwrap + Millisecond => Utc.timestamp_millis_opt(ts).unwrap(), + Second => Utc.timestamp_opt(ts, 0).unwrap(), + }; + + let tz: Tz = timezone.parse().unwrap(); + let offset_seconds: i64 = tz + .offset_from_utc_datetime(&date_time.naive_utc()) + .fix() + .local_minus_utc() as i64; + + let adjusted_date_time = + date_time.add(TimeDelta::try_seconds(offset_seconds).unwrap()); + + // convert the navie datetime back to i64 + match T::UNIT { + Nanosecond => adjusted_date_time.timestamp_nanos_opt().unwrap(), // TODO chuynchun: remove unwrap + Microsecond => adjusted_date_time.timestamp_micros(), + Millisecond => adjusted_date_time.timestamp_millis(), + Second => adjusted_date_time.timestamp(), + } +} + +impl ScalarUDFImpl for ToLocalTimeFunc { + fn as_any(&self) -> &dyn Any { + self + } + + fn name(&self) -> &str { + "to_local_time" + } + + fn signature(&self) -> &Signature { + &self.signature + } + + fn return_type(&self, arg_types: &[DataType]) -> Result<DataType> { + if arg_types.len() != 1 { + return exec_err!( + "to_local_time function requires 1 argument, got {:?}", + arg_types.len() + ); + } + + match &arg_types[0] { + Timestamp(Nanosecond, _) => Ok(Timestamp(Nanosecond, None)), + Timestamp(Microsecond, _) => Ok(Timestamp(Microsecond, None)), + Timestamp(Millisecond, _) => Ok(Timestamp(Millisecond, None)), + Timestamp(Second, _) => Ok(Timestamp(Second, None)), + _ => exec_err!( + "The to_local_time function can only accept timestamp as the arg, got {:?}", arg_types[0] + ), + } + } + + fn invoke(&self, args: &[ColumnarValue]) -> Result<ColumnarValue> { + if args.len() != 1 { + return exec_err!( + "to_local_time function requires 1 argument, got {:?}", + args.len() + ); + } + + self.to_local_time(args) + } +} + +#[cfg(test)] +mod tests { + use std::sync::Arc; + + use arrow::array::{types::TimestampNanosecondType, TimestampNanosecondArray}; + use arrow::compute::kernels::cast_utils::string_to_timestamp_nanos; + use arrow::datatypes::{DataType, TimeUnit}; + use chrono::NaiveDateTime; + use datafusion_common::ScalarValue; + use datafusion_expr::{ColumnarValue, ScalarUDFImpl}; + + use super::ToLocalTimeFunc; + + #[test] + fn test_to_local_time() { + let res = ToLocalTimeFunc::new().invoke(&[ColumnarValue::Scalar( + ScalarValue::TimestampSecond(Some(1), None), + )]); + assert!(res.is_ok()); + + let res = ToLocalTimeFunc::new().invoke(&[ColumnarValue::Scalar( + ScalarValue::TimestampSecond(Some(1), Some("+01:00".into())), + )]); + assert!(res.is_ok()); + + let res = ToLocalTimeFunc::new().invoke(&[ColumnarValue::Scalar( + ScalarValue::TimestampNanosecond(Some(1), Some("Europe/Brussels".into())), + )]); + assert!(res.is_ok()); + + // + // Fallible test cases + // + + // invalid number of arguments -- no argument + let res = ToLocalTimeFunc::new().invoke(&[]); + assert_eq!( + res.err().unwrap().strip_backtrace(), + "Execution error: to_local_time function requires 1 argument, got 0" + ); + + // invalid number of arguments -- more than 1 argument + let res = ToLocalTimeFunc::new().invoke(&[ + ColumnarValue::Scalar(ScalarValue::TimestampSecond(Some(1), None)), + ColumnarValue::Scalar(ScalarValue::Utf8(Some("some string".to_string()))), + ]); + assert_eq!( + res.err().unwrap().strip_backtrace(), + "Execution error: to_local_time function requires 1 argument, got 2" + ); + + // invalid argument data type + let res = ToLocalTimeFunc::new().invoke(&[ColumnarValue::Scalar( + ScalarValue::Utf8(Some("some string".to_string())), + )]); + assert_eq!( + res.err().unwrap().strip_backtrace(), + "Execution error: to_local_time function requires timestamp argument, got Utf8" + ); + + // TODO chunchun: invalid timestamp: us, ms, s + } + + #[test] + fn test_to_local_time_scalar() { + let timezone = Some("Europe/Brussels".into()); + let timestamps_with_timezone = vec![ + ( + ScalarValue::TimestampNanosecond( + Some(1_123_123_000_000_000_000), + timezone.clone(), + ), + ScalarValue::TimestampNanosecond(Some(1_123_130_200_000_000_000), None), + ), + ( + ScalarValue::TimestampMicrosecond( + Some(1_123_123_000_000_000), + timezone.clone(), + ), + ScalarValue::TimestampMicrosecond(Some(1_123_130_200_000_000), None), + ), + ( + ScalarValue::TimestampMillisecond( + Some(1_123_123_000_000), + timezone.clone(), + ), + ScalarValue::TimestampMillisecond(Some(1_123_130_200_000), None), + ), + ( + ScalarValue::TimestampSecond(Some(1_123_123_000), timezone), + ScalarValue::TimestampSecond(Some(1_123_130_200), None), + ), + ]; + + for (input, expected) in timestamps_with_timezone { + test_to_local_time_helpfer(input, expected); + } + } + + #[test] + fn test_timezone_with_daylight_savings() { + let timezone_str = "America/New_York"; + + let test_cases = vec![ + // DST time + "2019-03-31T04:00:00", + "2020-03-31T13:40:00", + // End of DST + "2019-11-04T04:06:40", + "2020-11-04T14:06:40", + ]; + + for timestamp_str in test_cases { + // timestamp in local timezone + let tz: arrow::array::timezone::Tz = + timezone_str.parse().expect("Invalid timezone"); + let timestamp = timestamp_str + .parse::<NaiveDateTime>() + .unwrap() + .and_local_timezone(tz) // this is in a local timezone + .unwrap() + .timestamp_nanos_opt() + .unwrap(); + + // timestamp with no timezone + let expected_timestamp = timestamp_str + .parse::<NaiveDateTime>() + .unwrap() + .and_utc() // this is in UTC + .timestamp_nanos_opt() + .unwrap(); + + let input = ScalarValue::TimestampNanosecond( + Some(timestamp), + Some(timezone_str.into()), + ); + let expected = + ScalarValue::TimestampNanosecond(Some(expected_timestamp), None); + test_to_local_time_helpfer(input, expected) + } + } + + fn test_to_local_time_helpfer(input: ScalarValue, expected: ScalarValue) { + let res = ToLocalTimeFunc::new() + .invoke(&[ColumnarValue::Scalar(input)]) + .unwrap(); + match res { + ColumnarValue::Scalar(res) => { + assert_eq!(res, expected); + } + _ => panic!("unexpected return type"), + } + } + + #[test] + fn test_to_local_time_timezones_array() { + // TODO chunchun: might need to change string to Timestamp in cases Review Comment: This is a leftover comment and no longer needed. 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