From 5e9654aba7a366422c9a8c56e0ac5d461b7033e9 Mon Sep 17 00:00:00 2001
From: Mryange <yanxuecheng@selectdb.com>
Date: Tue, 22 Sep 2026 17:14:15 +0800
Subject: [PATCH 1/2] [fix](expr) enforce nullable column output matching

---
 be/src/exprs/vexpr.cpp       | 9 ---------
 be/test/exprs/vexpr_test.cpp | 7 +++----
 2 files changed, 3 insertions(+), 13 deletions(-)

diff --git a/be/src/exprs/vexpr.cpp b/be/src/exprs/vexpr.cpp
index 557d04a4e1f522..3c06f3bbdee89f 100644
--- a/be/src/exprs/vexpr.cpp
+++ b/be/src/exprs/vexpr.cpp
@@ -1075,15 +1075,6 @@ Status VExpr::execute_column(VExprContext* context, const Block* block, const Se
         auto result_type = execute_type(block);
         if (result_type != nullptr) {
             Status st = result_type->check_column(*result_column);
-            if (!st.ok()) {
-                // Nullable(T) may legitimately produce a non-nullable T column when all rows are
-                // non-null (use_default_implementation_for_nulls optimization). Allow this.
-                const auto* nullable_type =
-                        check_and_get_data_type<DataTypeNullable>(result_type.get());
-                if (nullable_type && !check_and_get_column<ColumnNullable>(result_column.get())) {
-                    st = nullable_type->get_nested_type()->check_column(*result_column);
-                }
-            }
             if (!st.ok()) {
                 return Status::InternalError(
                         "Expr {} return column type mismatch: declared={}, actual={}", expr_name(),
diff --git a/be/test/exprs/vexpr_test.cpp b/be/test/exprs/vexpr_test.cpp
index 10bdfb815d7d57..939a4d2472e7cb 100644
--- a/be/test/exprs/vexpr_test.cpp
+++ b/be/test/exprs/vexpr_test.cpp
@@ -893,11 +893,10 @@ TEST(VExprExecuteColumnTest, TypeMismatchFails) {
     EXPECT_FALSE(st.ok());
 }
 
-TEST(VExprExecuteColumnTest, NullableTypeWithNonNullableColumnPasses) {
+TEST(VExprExecuteColumnTest, NullableTypeWithNonNullableColumnFails) {
     using namespace doris;
     FakeVExpr expr;
-    // Declared type is Nullable(Int32) but result is Int32 (non-nullable).
-    // This mirrors the use_default_implementation_for_nulls optimization and must pass.
+    // Declared type is Nullable(Int32), so the result must carry a nullable column wrapper.
     expr.set_data_type(std::make_shared<DataTypeNullable>(std::make_shared<DataTypeInt32>()));
 
     auto col = ColumnInt32::create();
@@ -906,7 +905,7 @@ TEST(VExprExecuteColumnTest, NullableTypeWithNonNullableColumnPasses) {
 
     ColumnPtr result;
     auto st = expr.execute_column(nullptr, nullptr, nullptr, 1, result);
-    EXPECT_TRUE(st.ok());
+    EXPECT_FALSE(st.ok());
 }
 
 TEST(VExprExecuteColumnTest, ColumnNothingPassesTypeCheck) {

From 5c2500f7b54b12c4358f5616db6c2a726ab7b84a Mon Sep 17 00:00:00 2001
From: Mryange <yanxuecheng@selectdb.com>
Date: Wed, 23 Sep 2026 09:42:58 +0800
Subject: [PATCH 2/2] [fix](expr) Wrap non-null results for nullable
 expressions

---
 be/src/exprs/vexpr.cpp       | 3 +++
 be/test/exprs/vexpr_test.cpp | 5 +++--
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/be/src/exprs/vexpr.cpp b/be/src/exprs/vexpr.cpp
index 3c06f3bbdee89f..e49bb037865582 100644
--- a/be/src/exprs/vexpr.cpp
+++ b/be/src/exprs/vexpr.cpp
@@ -1074,6 +1074,9 @@ Status VExpr::execute_column(VExprContext* context, const Block* block, const Se
     if (!check_and_get_column<ColumnNothing>(result_column.get())) {
         auto result_type = execute_type(block);
         if (result_type != nullptr) {
+            if (result_type->is_nullable() && !result_column->is_nullable()) {
+                result_column = make_nullable(result_column, false);
+            }
             Status st = result_type->check_column(*result_column);
             if (!st.ok()) {
                 return Status::InternalError(
diff --git a/be/test/exprs/vexpr_test.cpp b/be/test/exprs/vexpr_test.cpp
index 939a4d2472e7cb..6138fc89ea3489 100644
--- a/be/test/exprs/vexpr_test.cpp
+++ b/be/test/exprs/vexpr_test.cpp
@@ -893,7 +893,7 @@ TEST(VExprExecuteColumnTest, TypeMismatchFails) {
     EXPECT_FALSE(st.ok());
 }
 
-TEST(VExprExecuteColumnTest, NullableTypeWithNonNullableColumnFails) {
+TEST(VExprExecuteColumnTest, NullableTypeWithNonNullableColumnIsWrapped) {
     using namespace doris;
     FakeVExpr expr;
     // Declared type is Nullable(Int32), so the result must carry a nullable column wrapper.
@@ -905,7 +905,8 @@ TEST(VExprExecuteColumnTest, NullableTypeWithNonNullableColumnFails) {
 
     ColumnPtr result;
     auto st = expr.execute_column(nullptr, nullptr, nullptr, 1, result);
-    EXPECT_FALSE(st.ok());
+    EXPECT_TRUE(st.ok());
+    EXPECT_TRUE(result->is_nullable());
 }
 
 TEST(VExprExecuteColumnTest, ColumnNothingPassesTypeCheck) {