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Broadcast NestedLoopJoinExec #342

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54 changes: 27 additions & 27 deletions src/distributed_planner/distributed_physical_optimizer_rule.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -719,15 +719,15 @@ mod tests {
└──────────────────────────────────────────────────
┌───── Stage 2 ── Tasks: t0:[p0] t1:[p1] t2:[p2]
│ HashJoinExec: mode=CollectLeft, join_type=Inner, on=[(RainToday@1, RainToday@1)], projection=[MinTemp@0, MaxTemp@2]
│ CoalescePartitionsExec
│ [Stage 1] => NetworkBroadcastExec: partitions_per_consumer=1, stage_partitions=3, input_tasks=3
│ [Stage 1] => NetworkBroadcastExec: partitions_per_consumer=1, stage_partitions=3, input_tasks=3
│ PartitionIsolatorExec: t0:[p0,__,__] t1:[__,p0,__] t2:[__,__,p0]
│ DataSourceExec: file_groups={3 groups: [[/testdata/weather/result-000000.parquet], [/testdata/weather/result-000001.parquet], [/testdata/weather/result-000002.parquet]]}, projection=[MaxTemp, RainToday], file_type=parquet, predicate=DynamicFilter [ empty ]
└──────────────────────────────────────────────────
┌───── Stage 1 ── Tasks: t0:[p0..p2] t1:[p3..p5] t2:[p6..p8]
│ BroadcastExec: input_partitions=1, consumer_tasks=3, output_partitions=3
│ PartitionIsolatorExec: t0:[p0,__,__] t1:[__,p0,__] t2:[__,__,p0]
│ DataSourceExec: file_groups={3 groups: [[/testdata/weather/result-000000.parquet], [/testdata/weather/result-000001.parquet], [/testdata/weather/result-000002.parquet]]}, projection=[MinTemp, RainToday], file_type=parquet
│ CoalescePartitionsExec
│ PartitionIsolatorExec: t0:[p0,__,__] t1:[__,p0,__] t2:[__,__,p0]
│ DataSourceExec: file_groups={3 groups: [[/testdata/weather/result-000000.parquet], [/testdata/weather/result-000001.parquet], [/testdata/weather/result-000002.parquet]]}, projection=[MinTemp, RainToday], file_type=parquet
└──────────────────────────────────────────────────
")
}
Expand All @@ -748,23 +748,23 @@ mod tests {
└──────────────────────────────────────────────────
┌───── Stage 3 ── Tasks: t0:[p0] t1:[p1] t2:[p2]
│ HashJoinExec: mode=CollectLeft, join_type=Inner, on=[(RainToday@2, RainToday@1)], projection=[MinTemp@0, MaxTemp@1, Rainfall@3]
│ CoalescePartitionsExec
│ [Stage 2] => NetworkBroadcastExec: partitions_per_consumer=1, stage_partitions=3, input_tasks=3
│ [Stage 2] => NetworkBroadcastExec: partitions_per_consumer=1, stage_partitions=3, input_tasks=3
│ PartitionIsolatorExec: t0:[p0,__,__] t1:[__,p0,__] t2:[__,__,p0]
│ DataSourceExec: file_groups={3 groups: [[/testdata/weather/result-000000.parquet], [/testdata/weather/result-000001.parquet], [/testdata/weather/result-000002.parquet]]}, projection=[Rainfall, RainToday], file_type=parquet, predicate=DynamicFilter [ empty ]
└──────────────────────────────────────────────────
┌───── Stage 2 ── Tasks: t0:[p0..p2] t1:[p3..p5] t2:[p6..p8]
│ BroadcastExec: input_partitions=1, consumer_tasks=3, output_partitions=3
│ HashJoinExec: mode=CollectLeft, join_type=Inner, on=[(RainToday@1, RainToday@1)], projection=[MinTemp@0, MaxTemp@2, RainToday@3]
│ CoalescePartitionsExec
│ CoalescePartitionsExec
│ HashJoinExec: mode=CollectLeft, join_type=Inner, on=[(RainToday@1, RainToday@1)], projection=[MinTemp@0, MaxTemp@2, RainToday@3]
│ [Stage 1] => NetworkBroadcastExec: partitions_per_consumer=1, stage_partitions=3, input_tasks=3
│ PartitionIsolatorExec: t0:[p0,__,__] t1:[__,p0,__] t2:[__,__,p0]
│ DataSourceExec: file_groups={3 groups: [[/testdata/weather/result-000000.parquet], [/testdata/weather/result-000001.parquet], [/testdata/weather/result-000002.parquet]]}, projection=[MaxTemp, RainToday], file_type=parquet, predicate=DynamicFilter [ empty ]
│ PartitionIsolatorExec: t0:[p0,__,__] t1:[__,p0,__] t2:[__,__,p0]
│ DataSourceExec: file_groups={3 groups: [[/testdata/weather/result-000000.parquet], [/testdata/weather/result-000001.parquet], [/testdata/weather/result-000002.parquet]]}, projection=[MaxTemp, RainToday], file_type=parquet, predicate=DynamicFilter [ empty ]
└──────────────────────────────────────────────────
┌───── Stage 1 ── Tasks: t0:[p0..p2] t1:[p3..p5] t2:[p6..p8]
│ BroadcastExec: input_partitions=1, consumer_tasks=3, output_partitions=3
│ PartitionIsolatorExec: t0:[p0,__,__] t1:[__,p0,__] t2:[__,__,p0]
│ DataSourceExec: file_groups={3 groups: [[/testdata/weather/result-000000.parquet], [/testdata/weather/result-000001.parquet], [/testdata/weather/result-000002.parquet]]}, projection=[MinTemp, RainToday], file_type=parquet
│ CoalescePartitionsExec
│ PartitionIsolatorExec: t0:[p0,__,__] t1:[__,p0,__] t2:[__,__,p0]
│ DataSourceExec: file_groups={3 groups: [[/testdata/weather/result-000000.parquet], [/testdata/weather/result-000001.parquet], [/testdata/weather/result-000002.parquet]]}, projection=[MinTemp, RainToday], file_type=parquet
└──────────────────────────────────────────────────
")
}
Expand Down Expand Up @@ -793,15 +793,15 @@ mod tests {
└──────────────────────────────────────────────────
┌───── Stage 2 ── Tasks: t0:[p0] t1:[p1] t2:[p2]
│ HashJoinExec: mode=CollectLeft, join_type=Inner, on=[(RainToday@1, RainToday@1)], projection=[MinTemp@0, MaxTemp@2]
│ CoalescePartitionsExec
│ [Stage 1] => NetworkBroadcastExec: partitions_per_consumer=1, stage_partitions=3, input_tasks=3
│ [Stage 1] => NetworkBroadcastExec: partitions_per_consumer=1, stage_partitions=3, input_tasks=3
│ PartitionIsolatorExec: t0:[p0,__,__] t1:[__,p0,__] t2:[__,__,p0]
│ DataSourceExec: file_groups={3 groups: [[/testdata/weather/result-000000.parquet], [/testdata/weather/result-000001.parquet], [/testdata/weather/result-000002.parquet]]}, projection=[MaxTemp, RainToday], file_type=parquet, predicate=DynamicFilter [ empty ]
└──────────────────────────────────────────────────
┌───── Stage 1 ── Tasks: t0:[p0..p2] t1:[p3..p5] t2:[p6..p8]
│ BroadcastExec: input_partitions=1, consumer_tasks=3, output_partitions=3
│ PartitionIsolatorExec: t0:[p0,__,__] t1:[__,p0,__] t2:[__,__,p0]
│ DataSourceExec: file_groups={3 groups: [[/testdata/weather/result-000000.parquet], [/testdata/weather/result-000001.parquet], [/testdata/weather/result-000002.parquet]]}, projection=[MinTemp, RainToday], file_type=parquet
│ CoalescePartitionsExec
│ PartitionIsolatorExec: t0:[p0,__,__] t1:[__,p0,__] t2:[__,__,p0]
│ DataSourceExec: file_groups={3 groups: [[/testdata/weather/result-000000.parquet], [/testdata/weather/result-000001.parquet], [/testdata/weather/result-000002.parquet]]}, projection=[MinTemp, RainToday], file_type=parquet
└──────────────────────────────────────────────────
")
}
Expand Down Expand Up @@ -831,18 +831,18 @@ mod tests {
┌───── Stage 1 ── Tasks: t0:[p0..p2] t1:[p3..p5] t2:[p6..p8]
│ DistributedUnionExec: t0:[c0] t1:[c1] t2:[c2]
│ HashJoinExec: mode=CollectLeft, join_type=Inner, on=[(RainToday@1, RainToday@1)], projection=[MinTemp@0, MaxTemp@2]
│ CoalescePartitionsExec
│ BroadcastExec: input_partitions=3, consumer_tasks=1, output_partitions=3
│ BroadcastExec: input_partitions=1, consumer_tasks=1, output_partitions=1
│ CoalescePartitionsExec
│ DataSourceExec: file_groups={3 groups: [[/testdata/weather/result-000000.parquet], [/testdata/weather/result-000001.parquet], [/testdata/weather/result-000002.parquet]]}, projection=[MinTemp, RainToday], file_type=parquet
│ DataSourceExec: file_groups={3 groups: [[/testdata/weather/result-000000.parquet], [/testdata/weather/result-000001.parquet], [/testdata/weather/result-000002.parquet]]}, projection=[MaxTemp, RainToday], file_type=parquet, predicate=DynamicFilter [ empty ]
│ HashJoinExec: mode=CollectLeft, join_type=Inner, on=[(RainToday@1, RainToday@1)], projection=[MinTemp@0, MaxTemp@2]
│ CoalescePartitionsExec
│ BroadcastExec: input_partitions=3, consumer_tasks=1, output_partitions=3
│ BroadcastExec: input_partitions=1, consumer_tasks=1, output_partitions=1
│ CoalescePartitionsExec
│ DataSourceExec: file_groups={3 groups: [[/testdata/weather/result-000000.parquet], [/testdata/weather/result-000001.parquet], [/testdata/weather/result-000002.parquet]]}, projection=[MinTemp, RainToday], file_type=parquet
│ DataSourceExec: file_groups={3 groups: [[/testdata/weather/result-000000.parquet], [/testdata/weather/result-000001.parquet], [/testdata/weather/result-000002.parquet]]}, projection=[MaxTemp, RainToday], file_type=parquet, predicate=DynamicFilter [ empty ]
│ HashJoinExec: mode=CollectLeft, join_type=Inner, on=[(RainToday@1, RainToday@1)], projection=[MinTemp@0, MaxTemp@2]
│ CoalescePartitionsExec
│ BroadcastExec: input_partitions=3, consumer_tasks=1, output_partitions=3
│ BroadcastExec: input_partitions=1, consumer_tasks=1, output_partitions=1
│ CoalescePartitionsExec
│ DataSourceExec: file_groups={3 groups: [[/testdata/weather/result-000000.parquet], [/testdata/weather/result-000001.parquet], [/testdata/weather/result-000002.parquet]]}, projection=[MinTemp, RainToday], file_type=parquet
│ DataSourceExec: file_groups={3 groups: [[/testdata/weather/result-000000.parquet], [/testdata/weather/result-000001.parquet], [/testdata/weather/result-000002.parquet]]}, projection=[MaxTemp, RainToday], file_type=parquet, predicate=DynamicFilter [ empty ]
└──────────────────────────────────────────────────
Expand All @@ -864,14 +864,14 @@ mod tests {
└──────────────────────────────────────────────────
┌───── Stage 2 ── Tasks: t0:[p0] t1:[p1] t2:[p2]
│ HashJoinExec: mode=CollectLeft, join_type=Inner, on=[(RainToday@1, RainToday@1)], projection=[MinTemp@0, MaxTemp@2]
│ CoalescePartitionsExec
│ [Stage 1] => NetworkBroadcastExec: partitions_per_consumer=3, stage_partitions=9, input_tasks=1
│ [Stage 1] => NetworkBroadcastExec: partitions_per_consumer=1, stage_partitions=3, input_tasks=1
│ PartitionIsolatorExec: t0:[p0,__,__] t1:[__,p0,__] t2:[__,__,p0]
│ DataSourceExec: file_groups={3 groups: [[/testdata/weather/result-000000.parquet], [/testdata/weather/result-000001.parquet], [/testdata/weather/result-000002.parquet]]}, projection=[MaxTemp, RainToday], file_type=parquet, predicate=DynamicFilter [ empty ]
└──────────────────────────────────────────────────
┌───── Stage 1 ── Tasks: t0:[p0..p8]
│ BroadcastExec: input_partitions=3, consumer_tasks=3, output_partitions=9
│ DataSourceExec: file_groups={3 groups: [[/testdata/weather/result-000000.parquet], [/testdata/weather/result-000001.parquet], [/testdata/weather/result-000002.parquet]]}, projection=[MinTemp, RainToday], file_type=parquet
┌───── Stage 1 ── Tasks: t0:[p0..p2]
│ BroadcastExec: input_partitions=1, consumer_tasks=3, output_partitions=3
│ CoalescePartitionsExec
│ DataSourceExec: file_groups={3 groups: [[/testdata/weather/result-000000.parquet], [/testdata/weather/result-000001.parquet], [/testdata/weather/result-000002.parquet]]}, projection=[MinTemp, RainToday], file_type=parquet
└──────────────────────────────────────────────────
");
}
Expand Down
43 changes: 14 additions & 29 deletions src/distributed_planner/insert_broadcast.rs
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Expand Up @@ -5,8 +5,7 @@ use datafusion::common::tree_node::{Transformed, TreeNode};
use datafusion::config::ConfigOptions;
use datafusion::error::DataFusionError;
use datafusion::physical_plan::ExecutionPlan;
use datafusion::physical_plan::coalesce_partitions::CoalescePartitionsExec;
use datafusion::physical_plan::joins::{HashJoinExec, PartitionMode};
use datafusion::physical_plan::joins::{HashJoinExec, NestedLoopJoinExec, PartitionMode};

use crate::BroadcastExec;

Expand Down Expand Up @@ -121,17 +120,19 @@ pub(super) fn insert_broadcast_execs(
}

plan.transform_down(|node| {
let Some(hash_join) = node.as_any().downcast_ref::<HashJoinExec>() else {
let join_type = if let Some(join) = node.as_any().downcast_ref::<NestedLoopJoinExec>() {
join.join_type()
} else if let Some(join) = node.as_any().downcast_ref::<HashJoinExec>()
&& join.partition_mode() == &PartitionMode::CollectLeft
{
join.join_type()
} else {
return Ok(Transformed::no(node));
};
if hash_join.partition_mode() != &PartitionMode::CollectLeft {
return Ok(Transformed::no(node));
}

// Only broadcast when output is driven by the probe side.
// Joins that can emit build-side rows (left/left-semi/left-anti/left-mark/full) would
// duplicate output if the build is broadcast, thus are excluded.
let join_type = hash_join.join_type();
if !matches!(
join_type,
JoinType::Inner
Expand All @@ -148,30 +149,15 @@ pub(super) fn insert_broadcast_execs(
return Ok(Transformed::no(node));
};

// If build child is CoalescePartitionsExec get its input
// Otherwise, use the build child directly (DataSourceExec)
let broadcast_input = if let Some(coalesce) = build_child
.as_any()
.downcast_ref::<CoalescePartitionsExec>()
{
Arc::clone(coalesce.input())
} else {
Arc::clone(build_child)
};

Comment on lines -151 to -161
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@gabotechs gabotechs Feb 6, 2026 •
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There is one challenge with this kind of joins. There can be situations where what's immediately below the join node is not a CoalescePartitionsExec, it might be something like:

https://github.com/datafusion-contrib/datafusion-distributed/blob/692fa473abfe9d362fc6e7378da3270e99405c3b/tests/tpcds_plans_test.rs#L1465-L1469

This means that there might be a whole chain of nodes above the CoalescePartitionExec that need to be accounted for, and that ideally, they run below the BroadcastExec so that the compute happens only once.

// Insert BroadcastExec. consumer_task_count=1 is a placeholder and
// will be corrected during optimizer rule.
let broadcast = Arc::new(BroadcastExec::new(
broadcast_input,
Arc::clone(build_child),
1, // placeholder
));

// Always wrap with CoalescePartitionsExec
let new_build_child: Arc<dyn ExecutionPlan> =
Arc::new(CoalescePartitionsExec::new(broadcast));

let mut new_children: Vec<Arc<dyn ExecutionPlan>> = children.into_iter().cloned().collect();
new_children[0] = new_build_child;
new_children[0] = broadcast;
Ok(Transformed::yes(node.with_new_children(new_children)?))
})
.map(|transformed| transformed.data)
Expand Down Expand Up @@ -203,8 +189,8 @@ mod tests {
let plan = sql_to_plan_with_broadcast(query, true, 4).await;
assert_snapshot!(plan, @r"
HashJoinExec: mode=CollectLeft, join_type=Inner, on=[(RainToday@1, RainToday@1)], projection=[MinTemp@0, MaxTemp@2]
CoalescePartitionsExec
BroadcastExec: input_partitions=3, consumer_tasks=1, output_partitions=3
BroadcastExec: input_partitions=1, consumer_tasks=1, output_partitions=1
CoalescePartitionsExec
DataSourceExec: file_groups={3 groups: [[/testdata/weather/result-000000.parquet], [/testdata/weather/result-000001.parquet], [/testdata/weather/result-000002.parquet]]}, projection=[MinTemp, RainToday], file_type=parquet
DataSourceExec: file_groups={3 groups: [[/testdata/weather/result-000000.parquet], [/testdata/weather/result-000001.parquet], [/testdata/weather/result-000002.parquet]]}, projection=[MaxTemp, RainToday], file_type=parquet, predicate=DynamicFilter [ empty ]
");
Expand All @@ -226,9 +212,8 @@ mod tests {
let plan = sql_to_plan_with_broadcast(query, true, 1).await;
assert_snapshot!(plan, @r"
HashJoinExec: mode=CollectLeft, join_type=Inner, on=[(RainToday@1, RainToday@1)], projection=[MinTemp@0, MaxTemp@2]
CoalescePartitionsExec
BroadcastExec: input_partitions=1, consumer_tasks=1, output_partitions=1
DataSourceExec: file_groups={1 group: [[/testdata/weather/result-000000.parquet, /testdata/weather/result-000001.parquet, /testdata/weather/result-000002.parquet]]}, projection=[MinTemp, RainToday], file_type=parquet
BroadcastExec: input_partitions=1, consumer_tasks=1, output_partitions=1
DataSourceExec: file_groups={1 group: [[/testdata/weather/result-000000.parquet, /testdata/weather/result-000001.parquet, /testdata/weather/result-000002.parquet]]}, projection=[MinTemp, RainToday], file_type=parquet
DataSourceExec: file_groups={1 group: [[/testdata/weather/result-000000.parquet, /testdata/weather/result-000001.parquet, /testdata/weather/result-000002.parquet]]}, projection=[MaxTemp, RainToday], file_type=parquet, predicate=DynamicFilter [ empty ]
");
}
Expand Down
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