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Author: SkyFan2002

src/query/catalog/src/table_context.rs

@@ -419,6 +419,9 @@ pub trait TableContext: Send + Sync {
         unimplemented!()
     }
 
+    /// Calling this function will automatically create a pipeline for broadcast data in `build_distributed_pipeline()`
+    ///
+    /// The returned id can be used to get sender and receiver for broadcasting data.
     fn get_next_broadcast_id(&self) -> u32;
 
     fn reset_broadcast_id(&self) {

src/query/service/src/sessions/query_ctx.rs

@@ -291,13 +291,22 @@ impl QueryContext {
     pub fn broadcast_source_receiver(&self, broadcast_id: u32) -> Receiver<BlockMetaInfoPtr> {
         self.shared.broadcast_source_receiver(broadcast_id)
     }
+
+    /// Get a sender to broadcast data
+    ///
+    /// Note: The channel must be closed by calling close() after data transmission is completed
     pub fn broadcast_source_sender(&self, broadcast_id: u32) -> Sender<BlockMetaInfoPtr> {
         self.shared.broadcast_source_sender(broadcast_id)
     }
 
+    /// A receiver to receive broadcast data
+    ///
+    /// Note: receive() can be called repeatedly until an Error is returned, indicating
+    /// that the upstream channel has been closed
     pub fn broadcast_sink_receiver(&self, broadcast_id: u32) -> Receiver<BlockMetaInfoPtr> {
         self.shared.broadcast_sink_receiver(broadcast_id)
     }
+
     pub fn broadcast_sink_sender(&self, broadcast_id: u32) -> Sender<BlockMetaInfoPtr> {
         self.shared.broadcast_sink_sender(broadcast_id)
     }