From 96e26232dd34b6c944fd86d528be7f37197c69e0 Mon Sep 17 00:00:00 2001
From: PHILO-HE <feilong.he@intel.com>
Date: Wed, 8 Jan 2025 17:56:56 +0800
Subject: [PATCH] Fix casting varchar to timestamp

---
 .../sparksql/specialforms/SparkCastHooks.cpp       | 14 +++++++++++++-
 .../functions/sparksql/tests/SparkCastExprTest.cpp | 14 ++++++++++++++
 2 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/velox/functions/sparksql/specialforms/SparkCastHooks.cpp b/velox/functions/sparksql/specialforms/SparkCastHooks.cpp
index 37649fbf6747..6db8d1a96b77 100644
--- a/velox/functions/sparksql/specialforms/SparkCastHooks.cpp
+++ b/velox/functions/sparksql/specialforms/SparkCastHooks.cpp
@@ -31,8 +31,20 @@ SparkCastHooks::SparkCastHooks(const velox::core::QueryConfig& config)
 
 Expected<Timestamp> SparkCastHooks::castStringToTimestamp(
     const StringView& view) const {
-  return util::fromTimestampString(
+  auto conversionResult = util::fromTimestampString(
       view.data(), view.size(), util::TimestampParseMode::kSparkCast);
+  if (conversionResult.hasError()) {
+    return folly::makeUnexpected(conversionResult.error());
+  }
+  auto result = conversionResult.value();
+  // If no timezone information is available in the input string, check if we
+  // should understand it as being at the session timezone, and if so, convert
+  // to GMT.
+  const auto sessionTzName = config_.sessionTimezone();
+  if (!sessionTzName.empty()) {
+    result.toGMT(*tz::locateZone(sessionTzName));
+  }
+  return result;
 }
 
 Expected<Timestamp> SparkCastHooks::castIntToTimestamp(int64_t seconds) const {
diff --git a/velox/functions/sparksql/tests/SparkCastExprTest.cpp b/velox/functions/sparksql/tests/SparkCastExprTest.cpp
index ec7fb3034574..fcec9961658f 100644
--- a/velox/functions/sparksql/tests/SparkCastExprTest.cpp
+++ b/velox/functions/sparksql/tests/SparkCastExprTest.cpp
@@ -261,6 +261,20 @@ TEST_F(SparkCastExprTest, stringToTimestamp) {
       Timestamp(1426680197, 456000000),
   };
   testCast<std::string, Timestamp>("timestamp", input, expected);
+
+  setTimezone("Asia/Shanghai");
+  testCast<std::string, Timestamp>(
+      "timestamp",
+      {
+          "1970-01-01 00:00:00",
+          "1970-01-01 08:00:00",
+          "1970-01-01 08:00:59",
+      },
+      {
+          Timestamp(-8 * 3600, 0),
+          Timestamp(0, 0),
+          Timestamp(59, 0),
+      });
 }
 
 TEST_F(SparkCastExprTest, intToTimestamp) {