From 242c4e56d1e129fe208970e8fb67f4b38134a67b Mon Sep 17 00:00:00 2001
From: Vishwanatha-HD <Vishwanatha.HD@ibm.com>
Date: Fri, 21 Nov 2025 20:50:13 +0530
Subject: [PATCH] GH-48208 Fix Types logic to enable Parquet DB support on
 s390x

---
 cpp/src/parquet/types.cc | 19 ++++++++++++++++---
 cpp/src/parquet/types.h  | 11 +++++++++++
 2 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/cpp/src/parquet/types.cc b/cpp/src/parquet/types.cc
index fb4eb92a7544..96754270ae43 100644
--- a/cpp/src/parquet/types.cc
+++ b/cpp/src/parquet/types.cc
@@ -27,6 +27,7 @@
 #include "arrow/util/checked_cast.h"
 #include "arrow/util/compression.h"
 #include "arrow/util/decimal.h"
+#include "arrow/util/endian.h"
 #include "arrow/util/float16.h"
 #include "arrow/util/logging_internal.h"
 
@@ -112,6 +113,15 @@ std::enable_if_t<std::is_arithmetic_v<T>, std::string> FormatNumericValue(
   std::stringstream result;
   T value{};
   std::memcpy(&value, val.data(), sizeof(T));
+
+#if !ARROW_LITTLE_ENDIAN
+  // Parquet stores numeric stats in little-endian. Convert to native-endian
+  // before printing to avoid endianness mismatches on big-endian platforms.
+  if constexpr (std::is_integral_v<T> && sizeof(T) > 1) {
+    value = ::arrow::bit_util::FromLittleEndian(value);
+  }
+#endif
+
   result << value;
   return result.str();
 }
@@ -212,9 +222,12 @@ std::string FormatStatValue(Type::type parquet_type, ::std::string_view val,
       return FormatNumericValue<float>(val);
     }
     case Type::INT96: {
-      std::array<int32_t, 3> values{};
-      std::memcpy(values.data(), bytes, 3 * sizeof(int32_t));
-      result << values[0] << " " << values[1] << " " << values[2];
+      std::array<uint32_t, 3> values{};
+      std::memcpy(values.data(), bytes, 3 * sizeof(uint32_t));
+      // INT96 values are stored in little-endian format
+      result << ::arrow::bit_util::FromLittleEndian(values[0]) << " "
+             << ::arrow::bit_util::FromLittleEndian(values[1]) << " "
+             << ::arrow::bit_util::FromLittleEndian(values[2]);
       break;
     }
     case Type::BYTE_ARRAY:
diff --git a/cpp/src/parquet/types.h b/cpp/src/parquet/types.h
index 7e8a18fc94d6..942787cca189 100644
--- a/cpp/src/parquet/types.h
+++ b/cpp/src/parquet/types.h
@@ -26,6 +26,7 @@
 #include <string>
 #include <string_view>
 
+#include "arrow/util/endian.h"
 #include "parquet/platform.h"
 #include "parquet/type_fwd.h"
 #include "parquet/windows_fixup.h"  // for OPTIONAL
@@ -705,7 +706,12 @@ static inline std::string ByteArrayToString(const ByteArray& a) {
 }
 
 static inline void Int96SetNanoSeconds(parquet::Int96& i96, int64_t nanoseconds) {
+#if ARROW_LITTLE_ENDIAN
   std::memcpy(&i96.value, &nanoseconds, sizeof(nanoseconds));
+#else
+  i96.value[0] = static_cast<uint32_t>(nanoseconds);
+  i96.value[1] = static_cast<uint32_t>(nanoseconds >> 32);
+#endif
 }
 
 struct DecodedInt96 {
@@ -720,7 +726,12 @@ static inline DecodedInt96 DecodeInt96Timestamp(const parquet::Int96& i96) {
   result.days_since_epoch = i96.value[2] - static_cast<uint64_t>(kJulianToUnixEpochDays);
   result.nanoseconds = 0;
 
+#if ARROW_LITTLE_ENDIAN
   memcpy(&result.nanoseconds, &i96.value, sizeof(uint64_t));
+#else
+  result.nanoseconds =
+      static_cast<uint64_t>(i96.value[0]) | (static_cast<uint64_t>(i96.value[1]) << 32);
+#endif
   return result;
 }