alamb commented on code in PR #11734: URL: https://github.com/apache/datafusion/pull/11734#discussion_r1713002523
########## datafusion/physical-expr-common/src/aggregate/groups_accumulator/nulls.rs: ########## @@ -0,0 +1,87 @@ +// 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. + +//! XX utlities for working with nulls + +use arrow::array::{Array, ArrowNumericType, BooleanArray, PrimitiveArray}; +use arrow::buffer::NullBuffer; + +/// Sets the validity mask for a `PrimitiveArray` to `nulls` +/// replacing any existing null mask +pub fn set_nulls<T: ArrowNumericType + Send>( + array: PrimitiveArray<T>, + nulls: Option<NullBuffer>, +) -> PrimitiveArray<T> { + let (dt, values, _old_nulls) = array.into_parts(); + PrimitiveArray::<T>::new(values, nulls).with_data_type(dt) +} + +/// Converts a `BooleanBuffer` representing a filter to a `NullBuffer. +/// +/// The `NullBuffer` is +/// * `true` (representing valid) for values that were `true` in filter +/// * `false` (representing null) for values that were `false` or `null` in filter +fn filter_to_nulls(filter: &BooleanArray) -> Option<NullBuffer> { + let (filter_bools, filter_nulls) = filter.clone().into_parts(); + let filter_bools = NullBuffer::from(filter_bools); + NullBuffer::union(Some(&filter_bools), filter_nulls.as_ref()) +} + +/// Compute an output validity mask for an array that has been filtered +/// +/// This can be used to compute nulls for the output of +/// [`GroupsAccumulator::convert_to_state`], which quickly applies an optional +/// filter to the input rows by setting any filtered rows to NULL in the output. +/// Subsequent applications of aggregate functions that ignore NULLs (most of +/// them) will thus ignore the filtered rows as well. +/// +/// # Output element is `true` +/// * A `true` in the output represents non null output for all values that were both: +/// +/// * `true` in any `opt_filter` (aka values that passed the filter) +/// +/// * `non null` in `input` +/// +/// # Output element is `false` +/// * is false (null) for all values that were false in the filter or null in the input +/// +/// # Example +/// +/// ```text +/// ┌─────┐ ┌─────┐ ┌─────┐ +/// │true │ │NULL │ │NULL │ +/// │true │ │ │true │ │true │ +/// │true │ ───┼─── │false│ ────────▶ │false│ filtered_nulls +/// │false│ │ │NULL │ │NULL │ +/// │false│ │true │ │true │ +/// └─────┘ └─────┘ └─────┘ +/// array opt_filter output nulls Review Comment: Yes you are correct -- thank you for catching that. I fixed it in 149406bb6 -- 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
