Jimexist commented on a change in pull request #375: URL: https://github.com/apache/arrow-datafusion/pull/375#discussion_r639312957
########## File path: datafusion/src/physical_plan/expressions/row_number.rs ########## @@ -0,0 +1,172 @@ +// 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 `row_number` that can evaluated at runtime during query execution + +use crate::error::Result; +use crate::physical_plan::{ + window_functions::BuiltInWindowFunctionExpr, PhysicalExpr, WindowAccumulator, +}; +use crate::scalar::ScalarValue; +use arrow::array::{ArrayRef, UInt64Array}; +use arrow::datatypes::{DataType, Field}; +use std::any::Any; +use std::sync::Arc; + +/// row_number expression +#[derive(Debug)] +pub struct RowNumber { + name: String, +} + +impl RowNumber { + /// Create a new ROW_NUMBER function + pub fn new(name: String) -> Self { + Self { name } + } +} + +impl BuiltInWindowFunctionExpr for RowNumber { + /// 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::UInt64; + Ok(Field::new(&self.name, data_type, nullable)) + } + + fn expressions(&self) -> Vec<Arc<dyn PhysicalExpr>> { + vec![] + } + + fn name(&self) -> &str { + &self.name + } + + fn create_accumulator(&self) -> Result<Box<dyn WindowAccumulator>> { + Ok(Box::new(RowNumberAccumulator::new())) + } +} + +#[derive(Debug)] +struct RowNumberAccumulator { + row_number: u64, +} + +impl RowNumberAccumulator { + /// new count accumulator + pub fn new() -> Self { + // row number is 1 based + Self { row_number: 1 } + } +} + +impl WindowAccumulator for RowNumberAccumulator { + fn scan(&mut self, _values: &[ScalarValue]) -> Result<Option<ScalarValue>> { + let result = Some(ScalarValue::UInt64(Some(self.row_number))); + self.row_number += 1; + Ok(result) + } + + fn scan_batch( + &mut self, + num_rows: usize, + _values: &[ArrayRef], + ) -> Result<Option<ArrayRef>> { + let new_row_number = self.row_number + (num_rows as u64); + let result = UInt64Array::from_iter_values(self.row_number..new_row_number); Review comment: added a comment for this -- 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. For queries about this service, please contact Infrastructure at: [email protected]
