diff --git a/sql/catalyst/src/main/java/org/apache/spark/sql/catalyst/expressions/UnsafeArrayData.java b/sql/catalyst/src/main/java/org/apache/spark/sql/catalyst/expressions/UnsafeArrayData.java
index 02a863b2bb498..c867e5b3cb4c2 100644
--- a/sql/catalyst/src/main/java/org/apache/spark/sql/catalyst/expressions/UnsafeArrayData.java
+++ b/sql/catalyst/src/main/java/org/apache/spark/sql/catalyst/expressions/UnsafeArrayData.java
@@ -298,6 +298,10 @@ public UnsafeMapData getMap(int ordinal) {
     return map;
   }
 
+  // This `hashCode` computation could consume much processor time for large data.
+  // If the computation becomes a bottleneck, we can use a light-weight logic; the first fixed bytes
+  // are used to compute `hashCode` (See `Vector.hashCode`).
+  // The same issue exists in `UnsafeMapData.hashCode`.
   @Override
   public int hashCode() {
     return Murmur3_x86_32.hashUnsafeBytes(baseObject, baseOffset, sizeInBytes, 42);