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| 1 | +// Licensed to the Apache Software Foundation (ASF) under one |
| 2 | +// or more contributor license agreements. See the NOTICE file |
| 3 | +// distributed with this work for additional information |
| 4 | +// regarding copyright ownership. The ASF licenses this file |
| 5 | +// to you under the Apache License, Version 2.0 (the |
| 6 | +// "License"); you may not use this file except in compliance |
| 7 | +// with the License. You may obtain a copy of the License at |
| 8 | +// |
| 9 | +// http://www.apache.org/licenses/LICENSE-2.0 |
| 10 | +// |
| 11 | +// Unless required by applicable law or agreed to in writing, |
| 12 | +// software distributed under the License is distributed on an |
| 13 | +// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| 14 | +// KIND, either express or implied. See the License for the |
| 15 | +// specific language governing permissions and limitations |
| 16 | +// under the License. |
| 17 | + |
| 18 | +use crate::PhysicalOptimizerRule; |
| 19 | +use datafusion_common::JoinSide; |
| 20 | +use datafusion_common::config::ConfigOptions; |
| 21 | +use datafusion_common::tree_node::{Transformed, TransformedResult, TreeNode}; |
| 22 | +use datafusion_physical_plan::ExecutionPlan; |
| 23 | +use datafusion_physical_plan::buffer::BufferExec; |
| 24 | +use datafusion_physical_plan::joins::HashJoinExec; |
| 25 | +use std::sync::Arc; |
| 26 | + |
| 27 | +/// Looks for all the [HashJoinExec]s in the plan and places a [BufferExec] node with the |
| 28 | +/// configured capacity in the probe side: |
| 29 | +/// |
| 30 | +/// ```text |
| 31 | +/// ┌───────────────────┐ |
| 32 | +/// │ HashJoinExec │ |
| 33 | +/// └─────▲────────▲────┘ |
| 34 | +/// ┌───────┘ └─────────┐ |
| 35 | +/// │ │ |
| 36 | +/// ┌────────────────┐ ┌─────────────────┐ |
| 37 | +/// │ Build side │ + │ BufferExec │ |
| 38 | +/// └────────────────┘ └────────▲────────┘ |
| 39 | +/// │ |
| 40 | +/// ┌────────┴────────┐ |
| 41 | +/// │ Probe side │ |
| 42 | +/// └─────────────────┘ |
| 43 | +/// ``` |
| 44 | +/// |
| 45 | +/// Which allows eagerly pulling it even before the build side has completely finished. |
| 46 | +#[derive(Debug, Default)] |
| 47 | +pub struct HashJoinBuffering {} |
| 48 | + |
| 49 | +impl HashJoinBuffering { |
| 50 | + pub fn new() -> Self { |
| 51 | + Self::default() |
| 52 | + } |
| 53 | +} |
| 54 | + |
| 55 | +impl PhysicalOptimizerRule for HashJoinBuffering { |
| 56 | + fn optimize( |
| 57 | + &self, |
| 58 | + plan: Arc<dyn ExecutionPlan>, |
| 59 | + config: &ConfigOptions, |
| 60 | + ) -> datafusion_common::Result<Arc<dyn ExecutionPlan>> { |
| 61 | + let capacity = config.execution.hash_join_buffering_capacity; |
| 62 | + if capacity == 0 { |
| 63 | + return Ok(plan); |
| 64 | + } |
| 65 | + |
| 66 | + plan.transform_down(|plan| { |
| 67 | + let Some(node) = plan.as_any().downcast_ref::<HashJoinExec>() else { |
| 68 | + return Ok(Transformed::no(plan)); |
| 69 | + }; |
| 70 | + let plan = Arc::clone(&plan); |
| 71 | + Ok(Transformed::yes( |
| 72 | + if HashJoinExec::probe_side() == JoinSide::Left { |
| 73 | + // Do not stack BufferExec nodes together. |
| 74 | + if node.left.as_any().downcast_ref::<BufferExec>().is_some() { |
| 75 | + return Ok(Transformed::no(plan)); |
| 76 | + } |
| 77 | + plan.with_new_children(vec![ |
| 78 | + Arc::new(BufferExec::new(Arc::clone(&node.left), capacity)), |
| 79 | + Arc::clone(&node.right), |
| 80 | + ])? |
| 81 | + } else { |
| 82 | + // Do not stack BufferExec nodes together. |
| 83 | + if node.right.as_any().downcast_ref::<BufferExec>().is_some() { |
| 84 | + return Ok(Transformed::no(plan)); |
| 85 | + } |
| 86 | + plan.with_new_children(vec![ |
| 87 | + Arc::clone(&node.left), |
| 88 | + Arc::new(BufferExec::new(Arc::clone(&node.right), capacity)), |
| 89 | + ])? |
| 90 | + }, |
| 91 | + )) |
| 92 | + }) |
| 93 | + .data() |
| 94 | + } |
| 95 | + |
| 96 | + fn name(&self) -> &str { |
| 97 | + "HashJoinBuffering" |
| 98 | + } |
| 99 | + |
| 100 | + fn schema_check(&self) -> bool { |
| 101 | + true |
| 102 | + } |
| 103 | +} |
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