diff --git a/src/query/functions/src/lib.rs b/src/query/functions/src/lib.rs
index 7e15f0b7f042..9d41e6b42a70 100644
--- a/src/query/functions/src/lib.rs
+++ b/src/query/functions/src/lib.rs
@@ -41,8 +41,8 @@ pub fn is_builtin_function(name: &str) -> bool {
         || ASYNC_FUNCTIONS.contains(&name)
 }
 
-// The arguments of the search function, async function and udf are fetched from meta,
-// which may be modified by user at any time, not suitable for caching.
+// The plan of search function, async function and udf contains some arguments defined in meta,
+// which may be modified by user at any time. Those functions are not not suitable for caching.
 pub fn is_cacheable_function(name: &str) -> bool {
     BUILTIN_FUNCTIONS.contains(name)
         || AggregateFunctionFactory::instance().contains(name)