diff --git a/datafusion/expr/src/logical_plan/builder.rs b/datafusion/expr/src/logical_plan/builder.rs
index af9f66ca98c2..71097f5a61c6 100644
--- a/datafusion/expr/src/logical_plan/builder.rs
+++ b/datafusion/expr/src/logical_plan/builder.rs
@@ -989,6 +989,7 @@ pub fn project_with_alias(
     }
 }
 
+/// Create a SubqueryAlias to wrap a LogicalPlan.
 pub fn with_alias(plan: LogicalPlan, alias: String) -> LogicalPlan {
     let plan_schema = &**plan.schema();
     let schema = (plan_schema.clone()).replace_qualifier(alias.as_str());