From 421e24902d7d96f9b9df90318b8b6f341ad7d6fe Mon Sep 17 00:00:00 2001
From: Neil Conway <neil.conway@gmail.com>
Date: Fri, 19 Jun 2026 10:38:09 -0400
Subject: [PATCH] .

---
 .../joins/sort_merge_join/bitwise_stream.rs   |  1 +
 .../src/joins/sort_merge_join/tests.rs        | 99 +++++++++++++++++++
 2 files changed, 100 insertions(+)

diff --git a/datafusion/physical-plan/src/joins/sort_merge_join/bitwise_stream.rs b/datafusion/physical-plan/src/joins/sort_merge_join/bitwise_stream.rs
index 99aef6ed82a36..a26793f405a5a 100644
--- a/datafusion/physical-plan/src/joins/sort_merge_join/bitwise_stream.rs
+++ b/datafusion/physical-plan/src/joins/sort_merge_join/bitwise_stream.rs
@@ -1177,6 +1177,7 @@ impl BitwiseSortMergeJoinStream {
                                 self.emit_outer_batch()?;
                                 self.pending_boundary =
                                     Some(PendingBoundary::NoFilter { saved_keys });
+                                self.outer_batch = None;
 
                                 match ready!(self.poll_next_outer_batch(cx)) {
                                     Err(e) => return Poll::Ready(Err(e)),
diff --git a/datafusion/physical-plan/src/joins/sort_merge_join/tests.rs b/datafusion/physical-plan/src/joins/sort_merge_join/tests.rs
index 338c5111d223d..bc8b15472a63e 100644
--- a/datafusion/physical-plan/src/joins/sort_merge_join/tests.rs
+++ b/datafusion/physical-plan/src/joins/sort_merge_join/tests.rs
@@ -4342,6 +4342,105 @@ async fn no_filter_boundary_pending_loses_outer_rows() -> Result<()> {
     Ok(())
 }
 
+/// Verifies no-filter semi/anti joins when a matching outer key group spans
+/// multiple batches and the next outer batch is temporarily unavailable.
+///
+/// The outer input has an unmatched prefix row followed by a matching key
+/// group that continues in the next batch. Both rows with key=1 should be
+/// treated as matched. Returning `Pending` before the second batch forces
+/// `poll_join` to return and later resume from its top-level state, rather
+/// than continuing the same in-progress boundary loop.
+#[tokio::test]
+async fn no_filter_boundary_pending_with_unmatched_prefix() -> Result<()> {
+    let left_schema = Arc::new(Schema::new(vec![
+        Field::new("a1", DataType::Int32, false),
+        Field::new("b1", DataType::Int32, false),
+        Field::new("c1", DataType::Int32, false),
+    ]));
+    let right_schema = Arc::new(Schema::new(vec![
+        Field::new("a2", DataType::Int32, false),
+        Field::new("b1", DataType::Int32, false),
+        Field::new("c2", DataType::Int32, false),
+    ]));
+
+    // Key=0 is unmatched. Key=1 matches inner and spans the batch boundary.
+    let outer_batch1 = RecordBatch::try_new(
+        Arc::clone(&left_schema),
+        vec![
+            Arc::new(Int32Array::from(vec![0, 1])),
+            Arc::new(Int32Array::from(vec![0, 1])),
+            Arc::new(Int32Array::from(vec![0, 10])),
+        ],
+    )?;
+    let outer_batch2 = RecordBatch::try_new(
+        Arc::clone(&left_schema),
+        vec![
+            Arc::new(Int32Array::from(vec![2])),
+            Arc::new(Int32Array::from(vec![1])), // same key
+            Arc::new(Int32Array::from(vec![20])),
+        ],
+    )?;
+
+    // Key=1 matches two outer rows. Key=2 keeps the inner input non-exhausted.
+    let inner_batch = RecordBatch::try_new(
+        Arc::clone(&right_schema),
+        vec![
+            Arc::new(Int32Array::from(vec![100, 200])),
+            Arc::new(Int32Array::from(vec![1, 2])),
+            Arc::new(Int32Array::from(vec![50, 60])),
+        ],
+    )?;
+
+    let on_outer: Vec<PhysicalExprRef> = vec![Arc::new(Column::new("b1", 1))];
+    let on_inner: Vec<PhysicalExprRef> = vec![Arc::new(Column::new("b1", 1))];
+
+    for (join_type, expected_a1) in [(LeftSemi, vec![1, 2]), (LeftAnti, vec![0])] {
+        let outer: SendableRecordBatchStream = Box::pin(PendingStream::new(
+            vec![outer_batch1.clone(), outer_batch2.clone()],
+            vec![false, true], // Pending before 2nd outer batch
+        ));
+        let inner: SendableRecordBatchStream =
+            Box::pin(PendingStream::new(vec![inner_batch.clone()], vec![false]));
+
+        let metrics = ExecutionPlanMetricsSet::new();
+        let inner_schema = inner.schema();
+        let (reservation, spill_manager, runtime_env) =
+            test_stream_resources(inner_schema, &metrics);
+        let stream = BitwiseSortMergeJoinStream::try_new(
+            Arc::clone(&left_schema),
+            vec![SortOptions::default()],
+            NullEquality::NullEqualsNothing,
+            outer,
+            inner,
+            on_outer.clone(),
+            on_inner.clone(),
+            None, // no filter
+            join_type,
+            8192,
+            0,
+            &metrics,
+            reservation,
+            spill_manager,
+            runtime_env,
+        )?;
+
+        let batches = collect_stream(stream).await?;
+        let actual_a1 = batches
+            .iter()
+            .flat_map(|batch| {
+                let values = batch
+                    .column(0)
+                    .as_any()
+                    .downcast_ref::<Int32Array>()
+                    .unwrap();
+                (0..batch.num_rows()).map(|row| values.value(row))
+            })
+            .collect::<Vec<_>>();
+        assert_eq!(actual_a1, expected_a1, "{join_type:?}");
+    }
+    Ok(())
+}
+
 /// Tests the filtered boundary Pending re-entry: outer key group spans
 /// batches with a filter, and poll_next_outer_batch returns Pending.
 ///