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be/src/exec/vectorized/hash_join_node.cpp

@@ -350,6 +350,13 @@ bool HashJoinNode::_has_null(const ColumnPtr& column) {
 Status HashJoinNode::_build(RuntimeState* state) {
     {
         SCOPED_TIMER(_build_conjunct_evaluate_timer);
+        // Currently, in order to achieve simplicity, HashJoinNode uses BigChunk,
+        // Splice the Chunks from Scan on the right table into a big Chunk
+        // In some scenarios, such as when the left and right tables are selected incorrectly
+        // or when the large table is joined, the (BinaryColumn) in the Chunk exceeds the range of uint32_t,
+        // which will cause the output of wrong data.
+        // Currently, a defense needs to be added.
+        // After a better solution is available, the BigChunk mechanism can be removed.
         if (_ht.get_build_chunk()->exceed_capacity_limit()) {
             return Status::InternalError("Total size of single column exceed the limit of hash join");
         }