diff --git a/core/util.rs b/core/util.rs
index 406d7059f..8ab86c70a 100644
--- a/core/util.rs
+++ b/core/util.rs
@@ -578,6 +578,7 @@ pub fn can_pushdown_predicate(expr: &Expr) -> bool {
                 &name.0,
                 args.as_ref().map_or(0, |a| a.len()),
             );
+            // is deterministic
             matches!(function, Ok(Func::Scalar(_)))
         }
         Expr::Like { lhs, rhs, .. } => can_pushdown_predicate(lhs) && can_pushdown_predicate(rhs),
@@ -597,10 +598,6 @@ pub fn can_pushdown_predicate(expr: &Expr) -> bool {
     }
 }
 
-fn is_deterministic(func: &Func) -> bool {
-    matches!(func, Func::Scalar(_))
-}
-
 #[derive(Debug, Default, PartialEq)]
 pub struct OpenOptions<'a> {
     /// The authority component of the URI. may be 'localhost' or empty