From 15ead92089f74dd84668af4cb814bf9b4b3ffac7 Mon Sep 17 00:00:00 2001
From: Kevin H Wilson <khwilson@gmail.com>
Date: Sun, 13 Oct 2024 14:59:26 -0400
Subject: [PATCH] include hash aggregate sums

---
 cpp/src/arrow/compute/kernels/hash_aggregate.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/cpp/src/arrow/compute/kernels/hash_aggregate.cc b/cpp/src/arrow/compute/kernels/hash_aggregate.cc
index 21b7bd9bf6632..48ea9fbeb93c9 100644
--- a/cpp/src/arrow/compute/kernels/hash_aggregate.cc
+++ b/cpp/src/arrow/compute/kernels/hash_aggregate.cc
@@ -564,7 +564,7 @@ struct GroupedReducingAggregator : public GroupedAggregator {
   template <typename T = Type>
   static enable_if_decimal<T, std::shared_ptr<DataType>> GetOutType(
       const std::shared_ptr<DataType>& in_type) {
-    return in_type;
+    return WidenDecimalToMaxPrecision(in_type).ValueOrDie();
   }
 
   int64_t num_groups_ = 0;