Throw when null row is passed to multimap_from_entries (#11166)

Summary:
Pull Request resolved: #11166

Currently velox completely ignores null row entries in the input array whereas Presto throws when one is present. The change makes velox behave like Presto.

Reviewed By: kevinwilfong

Differential Revision: D63870933

fbshipit-source-id: 275500e375886eb8acbb72f57dc884c40590d4c0

velox/functions/prestosql/MultimapFromEntries.h

@@ -35,9 +35,10 @@ struct MultimapFromEntriesFunction {
     uniqueKeys_.clear();
     uniqueKeys_.reserve(inputArray.size());
 
-    for (const auto& entry : inputArray.skipNulls()) {
-      const auto& key = entry.template at<0>();
-      const auto& value = entry.template at<1>();
+    for (const auto& entry : inputArray) {
+      VELOX_USER_CHECK(entry.has_value(), "map entry cannot be null");
+      const auto& key = entry.value().template at<0>();
+      const auto& value = entry.value().template at<1>();
 
       VELOX_USER_CHECK(key.has_value(), "map key cannot be null");
 

velox/functions/prestosql/tests/MultimapFromEntriesTest.cpp

@@ -80,5 +80,29 @@ TEST_F(MultimapFromEntriesTest, nullKey) {
       "map key cannot be null");
 }
 
+TEST_F(MultimapFromEntriesTest, nullEntryFailure) {
+  RowVectorPtr rowVector = makeRowVector(
+      {makeFlatVector(std::vector<int64_t>{1, 2, 3}),
+       makeFlatVector(std::vector<int64_t>{4, 5, 6})});
+  rowVector->setNull(0, true);
+
+  ArrayVectorPtr input = makeArrayVector({0}, rowVector);
+
+  VELOX_ASSERT_THROW(
+      evaluate("multimap_from_entries(c0)", makeRowVector({input})),
+      "map entry cannot be null");
+
+  // Test that having a null entry in the base vector used to create the array
+  // vector does not cause a failure.
+  input = makeArrayVector({1}, rowVector);
+
+  auto expectedKeys = makeFlatVector<int64_t>({2, 3});
+  auto expectedValues = makeArrayVector<int64_t>({{5}, {6}});
+
+  auto expectedMap = makeMapVector({0}, expectedKeys, expectedValues);
+  auto result = evaluate("multimap_from_entries(c0)", makeRowVector({input}));
+  assertEqualVectors(expectedMap, result);
+}
+
 } // namespace
 } // namespace facebook::velox::functions