## Coverage Report

#### Created: 2024-10-13 08:39

    /Users/andrewlamb/Software/datafusion/datafusion/physical-expr/src/window/built_in.rs

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    // Licensed to the Apache Software Foundation (ASF) under one
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    // or more contributor license agreements.  See the NOTICE file
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    // distributed with this work for additional information
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    // regarding copyright ownership.  The ASF licenses this file
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    // to you under the Apache License, Version 2.0 (the
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    // "License"); you may not use this file except in compliance
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    // with the License.  You may obtain a copy of the License at
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    //
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    //   http://www.apache.org/licenses/LICENSE-2.0
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    //
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    // Unless required by applicable law or agreed to in writing,
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    // software distributed under the License is distributed on an
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    // "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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    // KIND, either express or implied.  See the License for the
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    // specific language governing permissions and limitations
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    // under the License.
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    //! Physical exec for built-in window function expressions.
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    use std::any::Any;
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    use std::ops::Range;
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    use std::sync::Arc;
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    use super::{BuiltInWindowFunctionExpr, WindowExpr};
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    use crate::expressions::PhysicalSortExpr;
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    use crate::window::window_expr::{get_orderby_values, WindowFn};
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    use crate::window::{PartitionBatches, PartitionWindowAggStates, WindowState};
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    use crate::{reverse_order_bys, EquivalenceProperties, PhysicalExpr};
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    use arrow::array::{new_empty_array, ArrayRef};
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    use arrow::compute::SortOptions;
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    use arrow::datatypes::Field;
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    use arrow::record_batch::RecordBatch;
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    use datafusion_common::utils::evaluate_partition_ranges;
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    use datafusion_common::{Result, ScalarValue};
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    use datafusion_expr::window_state::{WindowAggState, WindowFrameContext};
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    use datafusion_expr::WindowFrame;
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    /// A window expr that takes the form of a [`BuiltInWindowFunctionExpr`].
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    #[derive(Debug)]
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    pub struct BuiltInWindowExpr {
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        expr: Arc<dyn BuiltInWindowFunctionExpr>,
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        partition_by: Vec<Arc<dyn PhysicalExpr>>,
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        order_by: Vec<PhysicalSortExpr>,
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        window_frame: Arc<WindowFrame>,
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    }
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    impl BuiltInWindowExpr {
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        /// create a new built-in window function expression
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        pub fn new(
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            expr: Arc<dyn BuiltInWindowFunctionExpr>,
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            partition_by: &[Arc<dyn PhysicalExpr>],
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            order_by: &[PhysicalSortExpr],
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            window_frame: Arc<WindowFrame>,
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        ) -> Self {
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            Self {
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                expr,
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                partition_by: partition_by.to_vec(),
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                order_by: order_by.to_vec(),
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                window_frame,
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            }
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        }
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        /// Get BuiltInWindowFunction expr of BuiltInWindowExpr
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        pub fn get_built_in_func_expr(&self) -> &Arc<dyn BuiltInWindowFunctionExpr> {
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            &self.expr
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        }
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        /// Adds any equivalent orderings generated by the `self.expr`
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        /// to `builder`.
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        ///
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        /// If `self.expr` doesn't have an ordering, ordering equivalence properties
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        /// are not updated. Otherwise, ordering equivalence properties are updated
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        /// by the ordering of `self.expr`.
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        pub fn add_equal_orderings(&self, eq_properties: &mut EquivalenceProperties) {
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            let schema = eq_properties.schema();
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            if let Some(fn_res_ordering0) = self.expr.get_result_ordering(schema) {
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                if self.partition_by.is_empty() {
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                    // In the absence of a PARTITION BY, ordering of `self.expr` is global:
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                    eq_properties.add_new_orderings([vec![fn_res_ordering]]);
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                } else {
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                    // If we have a PARTITION BY, built-in functions can not introduce
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                    // a global ordering unless the existing ordering is compatible
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                    // with PARTITION BY expressions. To elaborate, when PARTITION BY
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                    // expressions and existing ordering expressions are equal (w.r.t.
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                    // set equality), we can prefix the ordering of `self.expr` with
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                    // the existing ordering.
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                    let (mut ordering, _) =
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                        eq_properties.find_longest_permutation(&self.partition_by);
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                    if ordering.len() == self.partition_by.len() {
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                        ordering.push(fn_res_ordering);
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                        eq_properties.add_new_orderings([ordering]);
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                    }
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                }
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            }
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        }
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    }
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    impl WindowExpr for BuiltInWindowExpr {
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        /// Return a reference to Any that can be used for downcasting
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        fn as_any(&self) -> &dyn Any {
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            self
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        }
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        fn name(&self) -> &str {
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            self.expr.name()
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        }
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        fn field(&self) -> Result<Field> {
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            self.expr.field()
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        }
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        fn expressions(&self) -> Vec<Arc<dyn PhysicalExpr>> {
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            self.expr.expressions()
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        }
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        fn partition_by(&self) -> &[Arc<dyn PhysicalExpr>] {
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            &self.partition_by
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        }
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        fn order_by(&self) -> &[PhysicalSortExpr] {
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            &self.order_by
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        }
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        fn evaluate(&self, batch: &RecordBatch) -> Result<ArrayRef> {
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            let mut evaluator = self.expr.create_evaluator()?;
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            let num_rows = batch.num_rows();
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            if evaluator.uses_window_frame() {
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                let sort_options: Vec<SortOptions> =
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                    self.order_by.iter().map(|o| o.options).collect();
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                let mut row_wise_results = vec![];
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                let mut values = self.evaluate_args(batch)?;
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                let order_bys = get_orderby_values(self.order_by_columns(batch)?);
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                let n_args = values.len();
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                values.extend(order_bys);
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                let order_bys_ref = &values[n_args..];
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                let mut window_frame_ctx =
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                    WindowFrameContext::new(Arc::clone(&self.window_frame), sort_options);
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                let mut last_range = Range { start: 0, end: 0 };
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                // We iterate on each row to calculate window frame range and and window function result
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                for idx in 0..num_rows {
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                    let range = window_frame_ctx.calculate_range(
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                        order_bys_ref,
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                        &last_range,
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                        num_rows,
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                        idx,
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                    )?;
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                    let value = evaluator.evaluate(&values, &range)?;
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                    row_wise_results.push(value);
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                    last_range = range;
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                }
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                ScalarValue::iter_to_array(row_wise_results)
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            } else if evaluator.include_rank() {
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                let columns = self.order_by_columns(batch)?;
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                let sort_partition_points = evaluate_partition_ranges(num_rows, &columns)?;
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                evaluator.evaluate_all_with_rank(num_rows, &sort_partition_points)
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            } else {
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                let values = self.evaluate_args(batch)?;
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                evaluator.evaluate_all(&values, num_rows)
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            }
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        }
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        /// Evaluate the window function against the batch. This function facilitates
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        /// stateful, bounded-memory implementations.
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        fn evaluate_stateful(
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            &self,
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            partition_batches: &PartitionBatches,
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            window_agg_state: &mut PartitionWindowAggStates,
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        ) -> Result<()> {
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            let field = self.expr.field()?0;
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            let out_type = field.data_type();
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            let sort_options = self.order_by.iter().map(|o| o.options0).collect::<Vec<_>>();
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            for (partition_row, partition_batch_state) in partition_batches.iter() {
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                let window_state =
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                    if let Some(window_state9) = window_agg_state.get_mut(partition_row) {
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                        window_state
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                    } else {
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                        let evaluator = self.expr.create_evaluator()?0;
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                        window_agg_state
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                            .entry(partition_row.clone())
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                            .or_insert(WindowState {
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                                state: WindowAggState::new(out_type)?0,
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                                window_fn: WindowFn::Builtin(evaluator),
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                            })
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                    };
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                let evaluator = match &mut window_state.window_fn {
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                    WindowFn::Builtin(evaluator) => evaluator,
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                    _ => unreachable!(),
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                };
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                let state = &mut window_state.state;
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                let batch_ref = &partition_batch_state.record_batch;
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                let mut values = self.evaluate_args(batch_ref)?0;
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                let order_bys = if evaluator.uses_window_frame() || evaluator.include_rank()0 {
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                    get_orderby_values(self.order_by_columns(batch_ref)?0)
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                } else {
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                    vec![]
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                };
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                let n_args = values.len();
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                values.extend(order_bys);
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                let order_bys_ref = &values[n_args..];
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                // We iterate on each row to perform a running calculation.
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                let record_batch = &partition_batch_state.record_batch;
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                let num_rows = record_batch.num_rows();
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                let mut row_wise_results: Vec<ScalarValue> = vec![];
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                let is_causal = if evaluator.uses_window_frame() {
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                    self.window_frame.is_causal()
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                } else {
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                    evaluator.is_causal()
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                };
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                for idx in state.last_calculated_index..num_rows12 {
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                    let frame_range = if evaluator.uses_window_frame() {
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                        state
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                            .window_frame_ctx
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                            .get_or_insert_with(|| {
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                                WindowFrameContext::new(
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                                    Arc::clone(&self.window_frame),
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                                    sort_options.clone(),
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                                )
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                            })
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                            .calculate_range(
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                                order_bys_ref,
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                                // Start search from the last range
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                                &state.window_frame_range,
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                                num_rows,
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                                idx,
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                            )
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                    } else {
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                        evaluator.get_range(idx, num_rows)
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    0
                    }?;
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                    // Exit if the range is non-causal and extends all the way:
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                    if frame_range.end == num_rows
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    9
                        && !is_causal
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    0
                        && !partition_batch_state.is_end
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                    {
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                        break;
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                    }
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                    // Update last range
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                    state.window_frame_range = frame_range;
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                    row_wise_results
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                        .push(evaluator.evaluate(&values, &state.window_frame_range)?0);
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                }
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                let out_col = if row_wise_results.is_empty() {
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    3
                    new_empty_array(out_type)
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                } else {
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    9
                    ScalarValue::iter_to_array(row_wise_results.into_iter())?0
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                };
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                state.update(&out_col, partition_batch_state)?0;
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                if self.window_frame.start_bound.is_unbounded() {
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                    evaluator.memoize(state)?0;
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    0
                }
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            }
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    12
            Ok(())
    258
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        }
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    3
        fn get_window_frame(&self) -> &Arc<WindowFrame> {
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            &self.window_frame
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        }
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    0
        fn get_reverse_expr(&self) -> Option<Arc<dyn WindowExpr>> {
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            self.expr.reverse_expr().map(|reverse_expr| {
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                Arc::new(BuiltInWindowExpr::new(
    267
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                    reverse_expr,
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                    &self.partition_by.clone(),
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    0
                    &reverse_order_bys(&self.order_by),
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    0
                    Arc::new(self.window_frame.reverse()),
    271
    0
                )) as _
    272
    0
            })
    273
    0
        }
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    0
        fn uses_bounded_memory(&self) -> bool {
    276
    0
            if let Ok(evaluator) = self.expr.create_evaluator() {
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    0
                evaluator.supports_bounded_execution()
    278
    0
                    && (!evaluator.uses_window_frame()
    279
    0
                        || !self.window_frame.end_bound.is_unbounded())
    280
            } else {
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    0
                false
    282
            }
    283
    0
        }
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    }