rluvaton commented on code in PR #13786: URL: https://github.com/apache/datafusion/pull/13786#discussion_r1893959228
########## 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"); + } + + let values = BooleanBuffer::collect_bool(lhs.len(), |i| cmp(i, i).is_le()); + + // No nulls as we only want to keep the values that are smaller, its either true or false + Ok(BooleanArray::new(values, None)) +} + +/// Return array where the smallest value at each index is kept +fn keep_smallest(lhs: ArrayRef, rhs: ArrayRef) -> Result<ArrayRef> { + // True for values that we should keep from the left array + let keep_lhs = get_smallest(lhs.as_ref(), rhs.as_ref())?; + + let smaller = zip(&keep_lhs, &lhs, &rhs)?; + + Ok(smaller) +} + +fn keep_smaller_scalar<'a>( + lhs: &'a ScalarValue, + rhs: &'a ScalarValue, +) -> Result<&'a ScalarValue> { + // Manual checking for nulls as: + // 1. If we're going to use <=, in Rust None is smaller than Some(T), which we don't want + // 2. And we can't use make_comparator as it has no natural order (Arrow error) + if lhs.is_null() { + return Ok(rhs); + } + + if rhs.is_null() { + return Ok(lhs); + } + + if !lhs.data_type().is_nested() { + return if lhs <= rhs { Ok(lhs) } else { Ok(rhs) }; + } + + // Not using <= as in Rust None is smaller than Some(T) + + // If complex type we can't compare directly as we want null values to be larger + let cmp = make_comparator( + lhs.to_array()?.as_ref(), + rhs.to_array()?.as_ref(), + SORT_OPTIONS, + )?; + + if cmp(0, 0).is_le() { + Ok(lhs) + } else { + Ok(rhs) + } +} + +fn find_coerced_type(data_types: &[DataType]) -> Result<DataType> { + if data_types.is_empty() { + plan_err!("least was called without any arguments. It requires at least 1.") + } else if let Some(coerced_type) = type_union_resolution(data_types) { + Ok(coerced_type) + } else { + plan_err!("Cannot find a common type for arguments") + } +} + +impl ScalarUDFImpl for LeastFunc { + fn as_any(&self) -> &dyn Any { + self + } + + fn name(&self) -> &str { + "least" + } + + fn signature(&self) -> &Signature { + &self.signature + } + + fn return_type(&self, arg_types: &[DataType]) -> Result<DataType> { + Ok(arg_types[0].clone()) + } + + fn invoke(&self, args: &[ColumnarValue]) -> Result<ColumnarValue> { + if args.is_empty() { + return exec_err!( Review Comment: changed ########## 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: used `internal_error` -- This is an automated message from the Apache Git Service. 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