jhorstmann commented on a change in pull request #8142: URL: https://github.com/apache/arrow/pull/8142#discussion_r485468664
########## File path: rust/datafusion/src/physical_plan/datetime_expressions.rs ########## @@ -0,0 +1,225 @@ +// 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. + +//! DateTime expressions + +use crate::error::{ExecutionError, Result}; +use arrow::array::{Array, ArrayRef, StringArray, TimestampNanosecondArray}; +use chrono::prelude::*; + +#[inline] +fn string_to_timestamp_nanos(s: &str) -> Result<i64> { Review comment: I'd be interested in a benchmark of this function or the kernel, maybe one for the happy case with `T` and `Z` and one for the last fallback. From my experience with Java, [parsing timestamps can be rather slow][1] and it might be worth writing a specialized implementation. The behaviour regarding time zones should also be documented, does it default to a local time zone or to always to UTC? Lastly, storing nanoseconds as i64 gives a range of about year 1677 to 2262, this might be a limitation for currently very few usecases but should also be mentioned. [1]: https://github.com/jhorstmann/packedtime#benchmarks ---------------------------------------------------------------- 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. For queries about this service, please contact Infrastructure at: us...@infra.apache.org
