Xuanwo commented on code in PR #23828: URL: https://github.com/apache/datafusion/pull/23828#discussion_r3701254555
########## datafusion/physical-plan/src/joins/asof_join.rs: ########## @@ -0,0 +1,1782 @@ +// 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. + +//! Broadcast, left-preserving ASOF join execution. +//! +//! An ASOF join emits exactly one output row for every left row. Within an +//! optional equality-key group, it selects the closest right row that satisfies +//! one ordered comparison: +//! +//! ```text +//! left.ts >= right.ts => greatest eligible right.ts +//! left.ts <= right.ts => smallest eligible right.ts +//! ``` +//! +//! The right input is collected and shared by all output partitions. The left +//! input remains partitioned, and each partition performs an independent +//! monotonic scan over the ordered right input: +//! +//! ```text +//! AsOfJoinExec Review Comment: Agreed! I added a note that broadcast-left and repartitioned strategies can follow for other input-size and key-distribution profiles. ########## datafusion/physical-plan/src/joins/asof_join.rs: ########## @@ -0,0 +1,1782 @@ +// 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. + +//! Broadcast, left-preserving ASOF join execution. +//! +//! An ASOF join emits exactly one output row for every left row. Within an +//! optional equality-key group, it selects the closest right row that satisfies +//! one ordered comparison: +//! +//! ```text +//! left.ts >= right.ts => greatest eligible right.ts +//! left.ts <= right.ts => smallest eligible right.ts +//! ``` +//! +//! The right input is collected and shared by all output partitions. The left +//! input remains partitioned, and each partition performs an independent +//! monotonic scan over the ordered right input: +//! +//! ```text +//! AsOfJoinExec +//! SortExec(left equality keys, left match key) +//! RepartitionExec(RoundRobinBatch) +//! left +//! SortExec(right equality keys, right match key) +//! CoalescePartitionsExec +//! right +//! ``` +//! +//! Both inputs must be ordered by their equality keys followed by the match +//! key. For `<` and `<=`, the match ordering is reversed so all directions use +//! the same forward-only state machine. Each left partition owns its cursors, +//! equality-group state, and current candidate, while the collected right +//! batches are immutable and shared. +//! +//! This mode preserves probe-side parallelism when there are no equality keys +//! or when equality keys have low cardinality or skew. It retains the complete +//! right input in the memory pool and may scan it once per left partition, so a +//! repartitioned streaming mode remains a useful future alternative for large +//! right inputs. + +use std::cmp::Ordering; +use std::collections::{HashMap, HashSet}; +use std::fmt::Formatter; +use std::sync::Arc; + +use arrow::array::{Array, ArrayRef, RecordBatch, new_null_array}; +use arrow::buffer::NullBuffer; +use arrow::compute::{SortOptions, interleave}; +use arrow::datatypes::{Schema, SchemaRef}; +use datafusion_common::config::ConfigOptions; +use datafusion_common::stats::Precision; +use datafusion_common::utils::memory::RecordBatchMemoryCounter; +use datafusion_common::utils::normalize_float_zero_scalar; +use datafusion_common::{ + ColumnStatistics, JoinType, NullEquality, Result, ScalarValue, Statistics, + assert_eq_or_internal_err, internal_err, plan_err, +}; +use datafusion_execution::TaskContext; +use datafusion_execution::memory_pool::{MemoryConsumer, MemoryReservation}; +use datafusion_expr::Operator; +use datafusion_physical_expr::PhysicalSortExpr; +use datafusion_physical_expr::expressions::Column as PhysicalColumn; +use datafusion_physical_expr::projection::ProjectionMapping; +use datafusion_physical_expr::utils::collect_columns; +use datafusion_physical_expr_common::physical_expr::{ + PhysicalExprRef, fmt_sql, is_volatile, +}; +use datafusion_physical_expr_common::sort_expr::{LexOrdering, OrderingRequirements}; +use futures::{StreamExt, TryStreamExt, future::poll_fn, stream}; + +use crate::execution_plan::{Boundedness, EmissionType}; +use crate::filter_pushdown::{ + ChildFilterDescription, ChildPushdownResult, FilterDescription, FilterPushdownPhase, + FilterPushdownPropagation, +}; +use crate::joins::utils::{ + JoinKeyComparator, JoinOn, OnceAsync, build_join_schema, matchable_join_keys, +}; +use crate::memory::MemoryStream; +use crate::metrics::{ + BaselineMetrics, Count, ExecutionPlanMetricsSet, Gauge, MetricBuilder, + MetricCategory, MetricsSet, RecordOutput, Time, +}; +use crate::statistics::{ChildStats, StatisticsArgs}; +use crate::stream::RecordBatchStreamAdapter; +use crate::{ + DisplayAs, DisplayFormatType, Distribution, ExecutionPlan, ExecutionPlanProperties, + InputDistributionRequirements, PlanProperties, SendableRecordBatchStream, + check_if_same_properties, +}; + +/// Physical ordered comparison for an ASOF join. +#[derive(Debug, Clone)] +pub struct AsOfMatchExpr { + /// Expression evaluated against the left input. + pub left: PhysicalExprRef, + /// Ordered comparison operator. + pub op: Operator, + /// Expression evaluated against the right input. + pub right: PhysicalExprRef, +} + +impl AsOfMatchExpr { + /// Creates a physical ASOF match expression. + pub fn new(left: PhysicalExprRef, op: Operator, right: PhysicalExprRef) -> Self { + Self { left, op, right } + } +} + +/// A broadcast sort-merge ASOF join that emits one row for every left row. +#[derive(Debug)] +pub struct AsOfJoinExec { + left: Arc<dyn ExecutionPlan>, + right: Arc<dyn ExecutionPlan>, + on: JoinOn, + match_condition: AsOfMatchExpr, + right_output_indices: Vec<usize>, Review Comment: Added. -- This is an automated message from the Apache Git Service. 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