alamb commented on a change in pull request #1076: URL: https://github.com/apache/arrow-datafusion/pull/1076#discussion_r724381917
########## File path: datafusion/src/physical_plan/expressions/cume_dist.rs ########## @@ -0,0 +1,160 @@ +// 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. + +//! Defines physical expression for `cume_dist` that can evaluated +//! at runtime during query execution + +use crate::error::Result; +use crate::physical_plan::window_functions::PartitionEvaluator; +use crate::physical_plan::{window_functions::BuiltInWindowFunctionExpr, PhysicalExpr}; +use arrow::array::ArrayRef; +use arrow::array::Float64Array; +use arrow::datatypes::{DataType, Field}; +use arrow::record_batch::RecordBatch; +use std::any::Any; +use std::iter; +use std::ops::Range; +use std::sync::Arc; + +/// CumeDist calculates the cume_dist in the window function with order by +#[derive(Debug)] +pub struct CumeDist { + name: String, +} + +/// Create a cume_dist window function +pub fn cume_dist(name: String) -> CumeDist { + CumeDist { name } +} + +impl BuiltInWindowFunctionExpr for CumeDist { + /// Return a reference to Any that can be used for downcasting + fn as_any(&self) -> &dyn Any { + self + } + + fn field(&self) -> Result<Field> { + let nullable = false; + let data_type = DataType::Float64; + Ok(Field::new(self.name(), data_type, nullable)) + } + + fn expressions(&self) -> Vec<Arc<dyn PhysicalExpr>> { + vec![] + } + + fn name(&self) -> &str { + &self.name + } + + fn create_evaluator( + &self, + _batch: &RecordBatch, + ) -> Result<Box<dyn PartitionEvaluator>> { + Ok(Box::new(CumeDistEvaluator {})) + } +} + +pub(crate) struct CumeDistEvaluator; + +impl PartitionEvaluator for CumeDistEvaluator { + fn include_rank(&self) -> bool { + true + } + + fn evaluate_partition(&self, _partition: Range<usize>) -> Result<ArrayRef> { + unreachable!( + "cume_dist evaluation must be called with evaluate_partition_with_rank" + ) + } + + fn evaluate_partition_with_rank( + &self, + partition: Range<usize>, + ranks_in_partition: &[Range<usize>], + ) -> Result<ArrayRef> { + let scaler = (partition.end - partition.start) as f64; + let result = Float64Array::from_iter_values( + ranks_in_partition Review comment: 👍 -- 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: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
