jorgecarleitao commented on a change in pull request #8709: URL: https://github.com/apache/arrow/pull/8709#discussion_r526608341
########## File path: rust/datafusion/src/physical_plan/hash_join.rs ########## @@ -0,0 +1,467 @@ +// 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 the join plan for executing partitions in parallel and then joining the results +//! into a set of partitions. + +use std::sync::Arc; +use std::{ + any::Any, + collections::{HashMap, HashSet}, +}; + +use async_trait::async_trait; +use futures::{Stream, StreamExt, TryStreamExt}; + +use arrow::array::{make_array, Array, MutableArrayData}; +use arrow::datatypes::{Schema, SchemaRef}; +use arrow::error::Result as ArrowResult; +use arrow::record_batch::RecordBatch; + +use super::hash_utils::{build_join_schema, check_join_is_valid, JoinType}; +use super::{expressions::col, hash_aggregate::create_key}; +use crate::error::{DataFusionError, Result}; + +use super::{ + group_scalar::GroupByScalar, ExecutionPlan, Partitioning, RecordBatchStream, + SendableRecordBatchStream, +}; + +// An index of (batch, row) uniquely identifying a row in a part. +type Index = (usize, usize); +// A pair (left index, right index) +type JoinIndex = (usize, usize); +// A mapping "on" value -> list of row indexes with this key's value +// E.g. [1, 2] -> [(0, 3), (1, 6), (0, 8)] indicates that (column1, column2) = [1, 2] is true +// for rows 3 and 8 from batch 0 and row 6 from batch 1. +type JoinHashMap = HashMap<Vec<GroupByScalar>, Vec<Index>>; +type JoinLeftData = (JoinHashMap, Vec<RecordBatch>); + +/// join execution plan executes partitions in parallel and combines them into a set of +/// partitions. +#[derive(Debug)] +pub struct HashJoinExec { + /// left side + left: Arc<dyn ExecutionPlan>, + /// right side + right: Arc<dyn ExecutionPlan>, + /// Set of common columns used to join on + on: HashSet<String>, + /// How the join is performed + join_type: JoinType, + /// The schema once the join is applied + schema: SchemaRef, +} + +impl HashJoinExec { + /// Create a new HashJoinExec + pub fn try_new( + left: Arc<dyn ExecutionPlan>, + right: Arc<dyn ExecutionPlan>, + on: &HashSet<String>, + join_type: &JoinType, + ) -> Result<Self> { + let left_schema = left.schema(); + let right_schema = right.schema(); + check_join_is_valid(&left_schema, &right_schema, &on)?; + + let on = on.iter().map(|s| s.clone()).collect::<HashSet<_>>(); + + let schema = Arc::new(build_join_schema(&left_schema, &right_schema, &on, &join_type)?); + + Ok(HashJoinExec { + left, + right, + on: on.clone(), + join_type: join_type.clone(), + schema, + }) + } +} + +#[async_trait] +impl ExecutionPlan for HashJoinExec { + fn as_any(&self) -> &dyn Any { + self + } + + fn schema(&self) -> SchemaRef { + self.schema.clone() + } + + fn children(&self) -> Vec<Arc<dyn ExecutionPlan>> { + vec![self.left.clone(), self.right.clone()] + } + + fn with_new_children( + &self, + children: Vec<Arc<dyn ExecutionPlan>>, + ) -> Result<Arc<dyn ExecutionPlan>> { + match children.len() { + 2 => Ok(Arc::new(HashJoinExec::try_new( + children[0].clone(), + children[1].clone(), + &self.on, + &self.join_type, + )?)), + _ => Err(DataFusionError::Internal( + "HashJoinExec wrong number of children".to_string(), + )), + } + } + + fn output_partitioning(&self) -> Partitioning { + self.right.output_partitioning() + } + + async fn execute(&self, partition: usize) -> Result<SendableRecordBatchStream> { + // build the keys + let stream = self.left.execute(partition).await?; Review comment: this is wrong: we need to get all partitions from the left here. ---------------------------------------------------------------- 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: us...@infra.apache.org
