alamb commented on code in PR #13786: URL: https://github.com/apache/datafusion/pull/13786#discussion_r1891888338
########## datafusion/functions/src/core/least.rs: ########## @@ -0,0 +1,283 @@ +// 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 arrow::array::{make_comparator, Array, ArrayRef, BooleanArray}; +use arrow::compute::kernels::cmp; +use arrow::compute::kernels::zip::zip; +use arrow::compute::SortOptions; +use arrow::datatypes::DataType; +use arrow_buffer::BooleanBuffer; +use datafusion_common::{exec_err, plan_err, Result, ScalarValue}; +use datafusion_doc::Documentation; +use datafusion_expr::binary::type_union_resolution; +use datafusion_expr::scalar_doc_sections::DOC_SECTION_CONDITIONAL; +use datafusion_expr::ColumnarValue; +use datafusion_expr::{ScalarUDFImpl, Signature, Volatility}; +use std::any::Any; +use std::sync::{Arc, OnceLock}; + +const SORT_OPTIONS: SortOptions = SortOptions { + // Having the smallest result first + descending: false, + + // NULL will be greater than any other value + nulls_first: false, +}; + +#[derive(Debug)] +pub struct LeastFunc { + signature: Signature, +} + +impl Default for LeastFunc { + fn default() -> Self { + LeastFunc::new() + } +} + +impl LeastFunc { + pub fn new() -> Self { + Self { + signature: Signature::user_defined(Volatility::Immutable), + } + } +} + +fn get_logical_null_count(arr: &dyn Array) -> usize { + arr.logical_nulls() + .map(|n| n.null_count()) + .unwrap_or_default() +} + +/// Return boolean array where `arr[i] = lhs[i] <= rhs[i]` for all i, where `arr` is the result array +/// Nulls are always considered larger than any other value +fn get_smallest(lhs: &dyn Array, rhs: &dyn Array) -> Result<BooleanArray> { + // Fast path: + // If both arrays are not nested, have the same length and no nulls, we can use the faster vectorised kernel + // - If both arrays are not nested: Nested types, such as lists, are not supported as the null semantics are not well-defined. + // - both array does not have any nulls: cmp::lt_eq will return null if any of the input is null while we want to return false in that case + if !lhs.data_type().is_nested() + && get_logical_null_count(lhs) == 0 + && get_logical_null_count(rhs) == 0 + { + return cmp::lt_eq(&lhs, &rhs).map_err(|e| e.into()); + } + + let cmp = make_comparator(lhs, rhs, SORT_OPTIONS)?; + + if lhs.len() != rhs.len() { + return exec_err!("All arrays should have the same length for least comparison"); + } Review Comment: internal_err also would be appropriate to signal that this is not an expected error -- 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
