[GitHub] [arrow] alamb commented on a change in pull request #9086: [Rust] [DataFusion] [Experiment] Blocking threads filter

[GitBox <gi...@apache.org>]

alamb commented on a change in pull request #9086:
URL: https://github.com/apache/arrow/pull/9086#discussion_r551883985



##########
File path: rust/datafusion/src/physical_plan/filter.rs
##########
@@ -103,25 +103,23 @@ impl ExecutionPlan for FilterExec {
     }
 
     async fn execute(&self, partition: usize) -> Result<SendableRecordBatchStream> {
-        Ok(Box::pin(FilterExecStream {
-            schema: self.input.schema().clone(),
-            predicate: self.predicate.clone(),
-            input: self.input.execute(partition).await?,
-        }))
+        let predicate = self.predicate.clone();
+
+        let stream = self.input.execute(partition).await?;
+        let stream = stream.then(move |batch| {
+            let predicate = predicate.clone();
+            async move {
+                // Filtering batches is CPU-bounded and therefore justifies a dedicated thread pool
+                task::spawn_blocking(move || batch_filter(&batch?, &predicate))
+                    .await
+                    .unwrap()
+            }
+        });
+
+        Ok(Box::pin(SizedRecordBatchStream::new(stream, self.schema())))

Review comment:
       I think buffering with a channel is the Rust-y  way to get more parallel execution without unlimited buffering




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