appletreeisyellow commented on code in PR #11347: URL: https://github.com/apache/datafusion/pull/11347#discussion_r1672265164
########## datafusion/functions/src/datetime/to_local_time.rs: ########## @@ -0,0 +1,564 @@ +// 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::{Array, ArrayRef, PrimitiveBuilder}; +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::{DateTime, MappedLocalTime, Offset, TimeDelta, TimeZone, Utc}; +use datafusion_common::cast::as_primitive_array; +use datafusion_common::{exec_err, DataFusionError, 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. +#[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| { + [ + Exact(vec![Timestamp(array_type, None)]), + Exact(vec![Timestamp(array_type, Some(TIMEZONE_WILDCARD.into()))]), + ] + }; + + let full_sig = [Nanosecond, Microsecond, Millisecond, Second] + .into_iter() + .flat_map(base_sig) + .collect::<Vec<_>>(); + + 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]; + 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. Therefore, + // 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(timezone)) => { + let tz: Tz = timezone.parse()?; + + match time_value { + ColumnarValue::Scalar(ScalarValue::TimestampNanosecond( + Some(ts), + Some(_), + )) => { + 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(_), + )) => { + 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(_), + )) => { + 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(_), + )) => { + 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: ArrowTimestampType>( + array: &ArrayRef, + tz: Tz, + ) -> Result<ColumnarValue> { + let mut builder = PrimitiveBuilder::<T>::new(); + + let primitive_array = as_primitive_array::<T>(array)?; + for ts_opt in primitive_array.iter() { + match ts_opt { + None => builder.append_null(), + Some(ts) => { + let adjusted_ts: i64 = + adjust_to_local_time::<T>(ts, tz)?; + builder.append_value(adjusted_ts) + } + } + } + + Ok(ColumnarValue::Array(Arc::new(builder.finish()))) Review Comment: Yeah, it would be neat to use `try_unary`. I got the same compiling error when I used `try_unary`, so I rewrote the code in a for loop with `PrimitiveBuilder` -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: github-unsubscr...@datafusion.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: github-unsubscr...@datafusion.apache.org For additional commands, e-mail: github-h...@datafusion.apache.org
