saadtajwar commented on code in PR #23957:
URL: https://github.com/apache/datafusion/pull/23957#discussion_r3739622020


##########
datafusion/physical-plan/src/joins/hash_join/stream.rs:
##########
@@ -742,40 +742,58 @@ impl HashJoinStream {
         let timer = self.join_metrics.join_time.timer();
 
         // Null-aware anti join semantics:
+
         // For LeftAnti: output LEFT (build) rows where LEFT.key NOT IN 
RIGHT.key
         // 1. If RIGHT (probe) contains NULL in any batch, no LEFT rows should 
be output
         // 2. LEFT rows with NULL keys should not be output (handled in final 
stage)
+
+        // For RightAnti: output RIGHT (probe) rows where RIGHT.key NOT IN 
LEFT.key
+        // 1. If LEFT (build) contains NULL, no RIGHT rows should be output
+        // 2. RIGHT rows with NULL keys should not be output
+        // 3. If LEFT (build) is empty, all RIGHT rows should be output
         if self.null_aware {
-            // Mark that we've seen a probe batch with actual rows (probe side 
is non-empty)
-            // Only set this if batch has rows - empty batches don't count
-            // Use shared atomic state so all partitions can see this global 
information
-            if state.batch.num_rows() > 0 {
-                build_side
-                    .left_data
-                    .probe_side_non_empty
-                    .store(true, Ordering::Relaxed);
-            }
+            match self.join_type {
+                JoinType::RightAnti => {

Review Comment:
   Thanks, done! Added that condition to `can_swap_hash_join`



##########
datafusion/physical-plan/src/joins/hash_join/exec.rs:
##########
@@ -2330,6 +2338,8 @@ async fn collect_left_input(
         bounds = None;
     }
 
+    let build_has_null = !left_values.is_empty() && 
left_values[0].null_count() > 0;

Review Comment:
   Ah good catch - fixed to use those logical null masks!



##########
datafusion/physical-plan/src/joins/hash_join/stream.rs:
##########
@@ -894,14 +912,26 @@ impl HashJoinStream {
             last_joined_right_idx.map_or(0, |v| v + 1)
         };
 
-        let (left_indices, right_indices) = adjust_indices_by_join_type(
+        let (left_indices, mut right_indices) = adjust_indices_by_join_type(
             left_indices,
             right_indices,
             index_alignment_range_start..index_alignment_range_end,
             self.join_type,
             self.right_side_ordered,
         )?;
 
+        // If null-aware RightAnti join, we don't want to emit NULL probe keys

Review Comment:
   Ah I see, that makes sense, thanks! Pushed a change to address, please let 
me know your thoughts!



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