From 2c167e63439bc60eca4cbd09e2d08bfaa745dd94 Mon Sep 17 00:00:00 2001
From: micah-white <micahwhitecs@gmail.com>
Date: Tue, 9 May 2023 17:09:00 -0500
Subject: [PATCH] Only hash array data bitmaps if the null count is not 0

---
 cpp/src/arrow/scalar.cc | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/cpp/src/arrow/scalar.cc b/cpp/src/arrow/scalar.cc
index 1f467ad93b123..9c7c942683e58 100644
--- a/cpp/src/arrow/scalar.cc
+++ b/cpp/src/arrow/scalar.cc
@@ -153,9 +153,10 @@ struct ScalarHashImpl {
 
   Status ArrayHash(const ArrayData& a) {
     RETURN_NOT_OK(StdHash(a.length) & StdHash(a.GetNullCount()));
-    if (a.buffers[0] != nullptr) {
+    if (a.GetNullCount() != 0) {
       // We can't visit values without unboxing the whole array, so only hash
-      // the null bitmap for now.
+      // the null bitmap for now. Only hash the null bitmap if the null count
+      // is 0 to ensure hash consistency.
       RETURN_NOT_OK(BufferHash(*a.buffers[0]));
     }
     for (const auto& child : a.child_data) {