diff --git a/be/src/vec/functions/function_utility.cpp b/be/src/vec/functions/function_utility.cpp
index 665987afa4eaf4..b201434537625e 100644
--- a/be/src/vec/functions/function_utility.cpp
+++ b/be/src/vec/functions/function_utility.cpp
@@ -70,6 +70,8 @@ class FunctionSleep : public IFunction {
 
     bool use_default_implementation_for_nulls() const override { return false; }
 
+    // Sleep function should not be executed during open stage, this will makes fragment prepare
+    // waiting too long, so we do not use default impl.
     bool use_default_implementation_for_constants() const override { return false; }
 
     Status execute_impl(FunctionContext* context, Block& block, const ColumnNumbers& arguments,