native-engine/datafusion-ext-plans/src/window/mod.rs

// 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::sync::Arc;

use arrow::{array::ArrayRef, datatypes::FieldRef, record_batch::RecordBatch};
use arrow_schema::DataType;
use datafusion::{common::Result, physical_expr::PhysicalExprRef};

use crate::{
    agg::{AggFunction, agg::create_agg},
    window::{
        processors::{
            agg_processor::AggProcessor, cume_dist_processor::CumeDistProcessor,
            lead_processor::LeadProcessor, nth_value_processor::NthValueProcessor,
            percent_rank_processor::PercentRankProcessor, rank_processor::RankProcessor,
            row_number_processor::RowNumberProcessor,
        },
        window_context::WindowContext,
    },
};

pub mod processors;
pub mod window_context;

#[derive(Debug, Clone, Copy)]
pub enum WindowFunction {
    RankLike(WindowRankType),
    PercentRank,
    NthValue { ignore_nulls: bool },
    Lead,
    CumeDist,
    Agg(AggFunction),
}

#[derive(Debug, Clone, Copy)]
pub enum WindowRankType {
    RowNumber,
    Rank,
    DenseRank,
}

pub trait WindowFunctionProcessor: Send {
    fn process_batch(&mut self, context: &WindowContext, batch: &RecordBatch) -> Result<ArrayRef>;
}

#[derive(Debug, Clone)]
pub struct WindowExpr {
    field: FieldRef,
    func: WindowFunction,
    children: Vec<PhysicalExprRef>,
    return_type: DataType,
}

impl WindowExpr {
    pub fn new(
        func: WindowFunction,
        children: Vec<PhysicalExprRef>,
        field: FieldRef,
        return_type: DataType,
    ) -> Self {
        Self {
            field,
            func,
            children,
            return_type,
        }
    }

    pub fn create_processor(
        &self,
        context: &Arc<WindowContext>,
    ) -> Result<Box<dyn WindowFunctionProcessor>> {
        match self.func {
            WindowFunction::RankLike(WindowRankType::RowNumber) => {
                Ok(Box::new(RowNumberProcessor::new()))
            }
            WindowFunction::RankLike(WindowRankType::Rank) => {
                Ok(Box::new(RankProcessor::new(false)))
            }
            WindowFunction::RankLike(WindowRankType::DenseRank) => {
                Ok(Box::new(RankProcessor::new(true)))
            }
            WindowFunction::PercentRank => Ok(Box::new(PercentRankProcessor::new())),
            WindowFunction::Lead => Ok(Box::new(LeadProcessor::new(self.children.clone()))),
            WindowFunction::NthValue { ignore_nulls } => Ok(Box::new(NthValueProcessor::try_new(
                self.children.clone(),
                ignore_nulls,
            )?)),
            WindowFunction::CumeDist => Ok(Box::new(CumeDistProcessor::new())),
            WindowFunction::Agg(agg_func) => {
                let agg = create_agg(
                    agg_func.clone(),
                    &self.children,
                    &context.input_schema,
                    self.return_type.clone(),
                )?;
                Ok(Box::new(AggProcessor::try_new(agg)?))
            }
        }
    }

    pub fn requires_full_partition(&self) -> bool {
        matches!(
            self.func,
            WindowFunction::PercentRank | WindowFunction::Lead | WindowFunction::CumeDist
        )
    }
}