diff --git a/velox/functions/sparksql/ConcatWs.cpp b/velox/functions/sparksql/ConcatWs.cpp
index 8b745391cfdd0..ef88441b07a13 100644
--- a/velox/functions/sparksql/ConcatWs.cpp
+++ b/velox/functions/sparksql/ConcatWs.cpp
@@ -39,16 +39,9 @@ class ConcatWs : public exec::VectorFunction {
       const exec::LocalDecodedVector& decodedSeparator) const {
     auto arrayArgNum = decodedArrays.size();
     std::vector<const ArrayVector*> arrayVectors;
-    std::vector<DecodedVector*> elementsDecodedVectors;
     for (auto i = 0; i < arrayArgNum; ++i) {
       auto arrayVector = decodedArrays[i].get()->base()->as<ArrayVector>();
       arrayVectors.push_back(arrayVector);
-      auto elements = arrayVector->elements();
-      exec::LocalSelectivityVector nestedRows(context, elements->size());
-      nestedRows.get()->setAll();
-      exec::LocalDecodedVector elementsHolder(
-          context, *elements, *nestedRows.get());
-      elementsDecodedVectors.push_back(elementsHolder.get());
     }
 
     size_t totalResultBytes = 0;
@@ -61,16 +54,15 @@ class ConcatWs : public exec::VectorFunction {
       // Calculate size for array columns data.
       for (int i = 0; i < arrayArgNum; i++) {
         auto arrayVector = arrayVectors[i];
-        auto rawSizes = arrayVector->rawSizes();
-        auto rawOffsets = arrayVector->rawOffsets();
         auto indices = decodedArrays[i].get()->indices();
-        auto elementsDecoded = elementsDecodedVectors[i];
+        SelectivityVector nestedRows(arrayVector->elements()->size());
+        DecodedVector elementsDecoded(*arrayVector->elements(), nestedRows);
+        auto size = arrayVector->sizeAt(indices[row]);
+        auto offset = arrayVector->offsetAt(indices[row]);
 
-        auto size = rawSizes[indices[row]];
-        auto offset = rawOffsets[indices[row]];
         for (int j = 0; j < size; ++j) {
-          if (!elementsDecoded->isNullAt(offset + j)) {
-            auto element = elementsDecoded->valueAt<StringView>(offset + j);
+          if (!elementsDecoded.isNullAt(offset + j)) {
+            auto element = elementsDecoded.valueAt<StringView>(offset + j);
             // No matter empty string or not.
             ++allElements;
             totalResultBytes += element.size();
@@ -209,16 +201,9 @@ class ConcatWs : public exec::VectorFunction {
         decodedSeparator);
 
     std::vector<const ArrayVector*> arrayVectors;
-    std::vector<DecodedVector*> elementsDecodedVectors;
     for (auto i = 0; i < decodedArrays.size(); ++i) {
       auto arrayVector = decodedArrays[i].get()->base()->as<ArrayVector>();
       arrayVectors.push_back(arrayVector);
-      auto elements = arrayVector->elements();
-      exec::LocalSelectivityVector nestedRows(context, elements->size());
-      nestedRows.get()->setAll();
-      exec::LocalDecodedVector elementsHolder(
-          context, *elements, *nestedRows.get());
-      elementsDecodedVectors.push_back(elementsHolder.get());
     }
     // Allocate a string buffer.
     auto rawBuffer =
@@ -256,16 +241,15 @@ class ConcatWs : public exec::VectorFunction {
       for (auto itArgs = args.begin() + 1; itArgs != args.end(); ++itArgs) {
         if ((*itArgs)->typeKind() == TypeKind::ARRAY) {
           auto arrayVector = arrayVectors[i];
-          auto rawSizes = arrayVector->rawSizes();
-          auto rawOffsets = arrayVector->rawOffsets();
           auto indices = decodedArrays[i].get()->indices();
-          auto elementsDecoded = elementsDecodedVectors[i];
+          SelectivityVector nestedRows(arrayVector->elements()->size());
+          DecodedVector elementsDecoded(*arrayVector->elements(), nestedRows);
+          auto size = arrayVector->sizeAt(indices[row]);
+          auto offset = arrayVector->offsetAt(indices[row]);
 
-          auto size = rawSizes[indices[row]];
-          auto offset = rawOffsets[indices[row]];
           for (int k = 0; k < size; ++k) {
-            if (!elementsDecoded->isNullAt(offset + k)) {
-              auto element = elementsDecoded->valueAt<StringView>(offset + k);
+            if (!elementsDecoded.isNullAt(offset + k)) {
+              auto element = elementsDecoded.valueAt<StringView>(offset + k);
               copyToBuffer(
                   element,
                   isConstantSeparator()
diff --git a/velox/functions/sparksql/tests/ConcatWsTest.cpp b/velox/functions/sparksql/tests/ConcatWsTest.cpp
index 3e51838b448bc..4cf6703c68f2b 100644
--- a/velox/functions/sparksql/tests/ConcatWsTest.cpp
+++ b/velox/functions/sparksql/tests/ConcatWsTest.cpp
@@ -127,7 +127,7 @@ TEST_F(ConcatWsTest, stringArgsWithNulls) {
 
   auto result = evaluate<SimpleVector<StringView>>(
       "concat_ws('~','',c0,'x',NULL::VARCHAR)", makeRowVector({input}));
-  auto expected = makeNullableFlatVector<StringView>({
+  auto expected = makeFlatVector<StringView>({
       "~~x",
       "~x",
       "~a~x",
@@ -219,6 +219,13 @@ TEST_F(ConcatWsTest, arrayArgs) {
       "red--purple--green--red--purple--green",
   });
   velox::test::assertEqualVectors(expected, result);
+
+  // Constant arrays.
+  auto dummyInput = makeRowVector(makeRowType({VARCHAR()}), 1);
+  result = evaluate<SimpleVector<StringView>>(
+      "concat_ws('--', array['a','b','c'], array['d'])", dummyInput);
+  expected = makeFlatVector<StringView>({"a--b--c--d"});
+  velox::test::assertEqualVectors(expected, result);
 }
 
 TEST_F(ConcatWsTest, mixedStringAndArrayArgs) {