comphead commented on code in PR #672: URL: https://github.com/apache/datafusion-comet/pull/672#discussion_r1683348966
########## native/spark-expr/src/case_expr_or_null.rs: ########## @@ -0,0 +1,210 @@ +// 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, + fmt::{Debug, Display, Formatter}, + hash::{Hash, Hasher}, + sync::Arc, +}; + +use arrow::compute::nullif; +use arrow_array::{Array, BooleanArray, RecordBatch}; +use arrow_schema::{DataType, Schema}; + +use datafusion_common::{DataFusionError, Result}; +use datafusion_expr::ColumnarValue; +use datafusion_physical_plan::{DisplayAs, DisplayFormatType, PhysicalExpr}; + +use crate::utils::down_cast_any_ref; + +/// Specialization of `CASE WHEN .. THEN .. ELSE null END` where +/// the else condition is a null literal. +/// +/// CaseWhenExprOrNull is only safe to use for expressions that do not +/// have side effects, and it is only suitable to use for expressions +/// that are inexpensive to compute (such as a column reference) +/// because it will be evaluated for all rows in the batch rather +/// than just the rows where the predicate is true. +/// +/// The performance advantage of this expression is that it +/// avoids copying data and simply modifies the null bitmask +/// of the evaluated expression based on the inverse of the +/// predicate expression. +#[derive(Debug, Hash)] +pub struct CaseWhenExprOrNull { + /// The WHEN predicate + predicate: Arc<dyn PhysicalExpr>, + /// The THEN expression + expr: Arc<dyn PhysicalExpr>, +} + +impl CaseWhenExprOrNull { + pub fn new(predicate: Arc<dyn PhysicalExpr>, input: Arc<dyn PhysicalExpr>) -> Self { + Self { + predicate, + expr: input, + } + } +} + +impl Display for CaseWhenExprOrNull { + fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result { + write!( + f, + "ExprOrNull(predicate={}, expr={})", + self.predicate, self.expr + ) + } +} + +impl DisplayAs for CaseWhenExprOrNull { + fn fmt_as(&self, _: DisplayFormatType, f: &mut Formatter) -> std::fmt::Result { + write!( + f, + "ExprOrNull(predicate={}, expr={})", + self.predicate, self.expr + ) + } +} + +impl PhysicalExpr for CaseWhenExprOrNull { + fn as_any(&self) -> &dyn Any { + self + } + + fn data_type(&self, input_schema: &Schema) -> Result<DataType> { + self.expr.data_type(input_schema) + } + + fn nullable(&self, _input_schema: &Schema) -> Result<bool> { + Ok(true) + } + + fn evaluate(&self, batch: &RecordBatch) -> Result<ColumnarValue> { + if let ColumnarValue::Array(bit_mask) = self.predicate.evaluate(batch)? { + let bit_mask = bit_mask + .as_any() + .downcast_ref::<BooleanArray>() + .expect("predicate should evaluate to a boolean array"); + // invert the bitmask + let bit_mask = arrow::compute::kernels::boolean::not(bit_mask)?; + match self.expr.evaluate(batch)? { + ColumnarValue::Array(array) => Ok(ColumnarValue::Array(nullif(&array, &bit_mask)?)), + ColumnarValue::Scalar(_) => Err(DataFusionError::Execution( Review Comment: ```suggestion ColumnarValue::Scalar(_) => exec_err!( ``` -- 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
