diff --git a/velox/vector/ComplexVector.cpp b/velox/vector/ComplexVector.cpp
index a40329a3ccd83..256714558ea98 100644
--- a/velox/vector/ComplexVector.cpp
+++ b/velox/vector/ComplexVector.cpp
@@ -1327,6 +1327,216 @@ void MapVector::copyRanges(
   copyRangesImpl(source, ranges, &values_, &keys_);
 }
 
+namespace {
+
+struct UpdateSource {
+  vector_size_t entryIndex;
+  int8_t sourceIndex;
+};
+
+template <typename T>
+class UpdateMapRow {
+ public:
+  void insert(
+      const DecodedVector* decoded,
+      vector_size_t entryIndex,
+      int8_t sourceIndex) {
+    values_[decoded->valueAt<T>(entryIndex)] = {entryIndex, sourceIndex};
+  }
+
+  template <typename F>
+  void forEachEntry(F&& func) {
+    for (auto& [_, source] : values_) {
+      func(source);
+    }
+  }
+
+  void clear() {
+    values_.clear();
+  }
+
+ private:
+  folly::F14FastMap<T, UpdateSource> values_;
+};
+
+template <>
+class UpdateMapRow<void> {
+ public:
+  void insert(
+      const DecodedVector* decoded,
+      vector_size_t entryIndex,
+      int8_t sourceIndex) {
+    references_[{decoded, entryIndex}] = {entryIndex, sourceIndex};
+  }
+
+  template <typename F>
+  void forEachEntry(F&& func) {
+    for (auto& [_, source] : references_) {
+      func(source);
+    }
+  }
+
+  void clear() {
+    references_.clear();
+  }
+
+ private:
+  struct Reference {
+    const DecodedVector* decoded;
+    vector_size_t index;
+
+    bool operator==(const Reference& other) const {
+      return decoded->base()->equalValueAt(
+          other.decoded->base(),
+          decoded->index(index),
+          other.decoded->index(other.index));
+    }
+  };
+
+  struct ReferenceHasher {
+    uint64_t operator()(const Reference& key) const {
+      return key.decoded->base()->hashValueAt(key.decoded->index(key.index));
+    }
+  };
+
+  folly::F14FastMap<Reference, UpdateSource, ReferenceHasher> references_;
+};
+
+} // namespace
+
+template <TypeKind kKeyTypeKind>
+MapVectorPtr MapVector::updateImpl(
+    const std::vector<MapVectorPtr>& others,
+    bool deleteNullMapValue) const {
+  auto newNulls = nulls();
+  bool allocatedNewNulls = false;
+  for (auto& other : others) {
+    if (!other->nulls()) {
+      continue;
+    }
+    if (!newNulls) {
+      newNulls = other->nulls();
+      continue;
+    }
+    if (!allocatedNewNulls) {
+      auto* prevNewNulls = newNulls->as<uint64_t>();
+      newNulls = allocateNulls(size(), pool());
+      allocatedNewNulls = true;
+      bits::andBits(
+          newNulls->asMutable<uint64_t>(),
+          prevNewNulls,
+          other->rawNulls(),
+          0,
+          size());
+    }
+  }
+
+  auto newOffsets = allocateIndices(size(), pool());
+  auto* rawNewOffsets = newOffsets->asMutable<vector_size_t>();
+  auto newSizes = allocateIndices(size(), pool());
+  auto* rawNewSizes = newSizes->asMutable<vector_size_t>();
+
+  std::vector<DecodedVector> keys;
+  keys.reserve(1 + others.size());
+  for (auto& other : others) {
+    VELOX_CHECK(*keys_->type() == *other->keys_->type());
+    keys.emplace_back(*other->keys_);
+  }
+  keys.emplace_back(*keys_);
+
+  std::vector<std::vector<BaseVector::CopyRange>> ranges(1 + others.size());
+  UpdateMapRow<typename TypeTraits<kKeyTypeKind>::NativeType> mapRow;
+  vector_size_t numEntries = 0;
+  for (vector_size_t i = 0; i < size(); ++i) {
+    rawNewOffsets[i] = numEntries;
+    if (newNulls && bits::isBitNull(newNulls->as<uint64_t>(), i)) {
+      rawNewSizes[i] = 0;
+      continue;
+    }
+    bool needUpdate = false;
+    for (auto& other : others) {
+      if (other->sizeAt(i) > 0) {
+        needUpdate = true;
+        break;
+      }
+    }
+    if (!needUpdate) {
+      // Fast path for no update on current row.  Common in case of table
+      // mutability delta update.
+      rawNewSizes[i] = sizeAt(i);
+      if (sizeAt(i) > 0) {
+        ranges.back().push_back({offsetAt(i), numEntries, sizeAt(i)});
+        numEntries += sizeAt(i);
+      }
+      continue;
+    }
+    auto offset = offsetAt(i);
+    auto size = sizeAt(i);
+    for (vector_size_t j = 0; j < size; ++j) {
+      auto jj = offset + j;
+      VELOX_DCHECK(!keys.back().isNullAt(jj));
+      VELOX_DCHECK(!deleteNullMapValue || !values_->isNullAt(jj));
+      mapRow.insert(&keys.back(), jj, others.size());
+    }
+    for (int k = 0; k < others.size(); ++k) {
+      offset = others[k]->offsetAt(i);
+      size = others[k]->sizeAt(i);
+      for (vector_size_t j = 0; j < size; ++j) {
+        auto jj = offset + j;
+        VELOX_DCHECK(!keys[k].isNullAt(jj));
+        mapRow.insert(&keys[k], jj, k);
+      }
+    }
+    vector_size_t newSize = 0;
+    mapRow.forEachEntry([&](UpdateSource source) {
+      if (deleteNullMapValue) {
+        auto* vector = source.sourceIndex == others.size()
+            ? this
+            : others[source.sourceIndex].get();
+        if (vector->values_->isNullAt(source.entryIndex)) {
+          return;
+        }
+      }
+      ranges[source.sourceIndex].push_back(
+          {source.entryIndex, numEntries + newSize, 1});
+      ++newSize;
+    });
+    mapRow.clear();
+    rawNewSizes[i] = newSize;
+    numEntries += newSize;
+  }
+
+  auto newKeys = BaseVector::create(mapKeys()->type(), numEntries, pool());
+  auto newValues = BaseVector::create(mapValues()->type(), numEntries, pool());
+  for (int k = 0; k < ranges.size(); ++k) {
+    auto* vector = k == others.size() ? this : others[k].get();
+    newKeys->copyRanges(vector->mapKeys().get(), ranges[k]);
+    newValues->copyRanges(vector->mapValues().get(), ranges[k]);
+  }
+
+  return std::make_shared<MapVector>(
+      pool(),
+      type(),
+      std::move(newNulls),
+      size(),
+      std::move(newOffsets),
+      std::move(newSizes),
+      std::move(newKeys),
+      std::move(newValues));
+}
+
+MapVectorPtr MapVector::update(
+    const std::vector<MapVectorPtr>& others,
+    bool deleteNullMapValue) const {
+  VELOX_CHECK(!others.empty());
+  VELOX_CHECK(others.size() < std::numeric_limits<int8_t>::max());
+  for (auto& other : others) {
+    VELOX_CHECK_EQ(size(), other->size());
+  }
+  return VELOX_DYNAMIC_TYPE_DISPATCH(
+      updateImpl, keys_->typeKind(), others, deleteNullMapValue);
+}
+
 void RowVector::appendNulls(vector_size_t numberOfRows) {
   VELOX_CHECK_GE(numberOfRows, 0);
   if (numberOfRows == 0) {
diff --git a/velox/vector/ComplexVector.h b/velox/vector/ComplexVector.h
index 5104a2f680807..9ed61b8f0f0ac 100644
--- a/velox/vector/ComplexVector.h
+++ b/velox/vector/ComplexVector.h
@@ -614,6 +614,20 @@ class MapVector : public ArrayVectorBase {
 
   void validate(const VectorValidateOptions& options) const override;
 
+  /// Update this map vector (base) with a list of map vectors (updates) of same
+  /// size.  Maps are updated row-wise, i.e. for a certain key in each row, we
+  /// keep the entry from the last update map containing the key.  If no update
+  /// map contains the key, we use the entry from base.  Any null map in either
+  /// base or updates creates a null row in the result.
+  ///
+  /// When deleteNullMapValue is true, if a map value is null in update vector
+  /// (argument), we drop the entry from base, instead of overwriting it with an
+  /// entry with null value.  No null map value in base vector is allowed in
+  /// this case.
+  std::shared_ptr<MapVector> update(
+      const std::vector<std::shared_ptr<MapVector>>& others,
+      bool deleteNullMapValue) const;
+
  protected:
   virtual void resetDataDependentFlags(const SelectivityVector* rows) override {
     BaseVector::resetDataDependentFlags(rows);
@@ -629,6 +643,11 @@ class MapVector : public ArrayVectorBase {
   // get elements in key order in each map.
   BufferPtr elementIndices() const;
 
+  template <TypeKind kKeyTypeKind>
+  std::shared_ptr<MapVector> updateImpl(
+      const std::vector<std::shared_ptr<MapVector>>& others,
+      bool deleteNullMapValue) const;
+
   VectorPtr keys_;
   VectorPtr values_;
   bool sortedKeys_;
@@ -649,4 +668,5 @@ inline BufferPtr allocateOffsets(vector_size_t size, memory::MemoryPool* pool) {
 inline BufferPtr allocateSizes(vector_size_t size, memory::MemoryPool* pool) {
   return AlignedBuffer::allocate<vector_size_t>(size, pool, 0);
 }
+
 } // namespace facebook::velox
diff --git a/velox/vector/benchmarks/CMakeLists.txt b/velox/vector/benchmarks/CMakeLists.txt
index 0ebca6e668541..eb9c71e4d8782 100644
--- a/velox/vector/benchmarks/CMakeLists.txt
+++ b/velox/vector/benchmarks/CMakeLists.txt
@@ -28,3 +28,7 @@ add_executable(copy_benchmark CopyBenchmark.cpp)
 
 target_link_libraries(copy_benchmark velox_vector_test_lib Folly::folly
                       ${FOLLY_BENCHMARK})
+
+add_executable(velox_vector_map_update_benchmark MapUpdateBenchmark.cpp)
+target_link_libraries(velox_vector_map_update_benchmark velox_vector_test_lib
+                      Folly::folly ${FOLLY_BENCHMARK})
diff --git a/velox/vector/benchmarks/MapUpdateBenchmark.cpp b/velox/vector/benchmarks/MapUpdateBenchmark.cpp
new file mode 100644
index 0000000000000..25e169ab21472
--- /dev/null
+++ b/velox/vector/benchmarks/MapUpdateBenchmark.cpp
@@ -0,0 +1,101 @@
+/*
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "velox/vector/ComplexVector.h"
+#include "velox/vector/tests/utils/VectorMaker.h"
+
+#include <folly/Benchmark.h>
+#include <folly/init/Init.h>
+
+#include <random>
+
+namespace facebook::velox {
+namespace {
+
+MapVectorPtr generateBase(
+    memory::MemoryPool* pool,
+    std::default_random_engine& gen) {
+  constexpr int kSize = 1000;
+  constexpr int kMapSize = 10;
+  test::VectorMaker maker(pool);
+  std::uniform_real_distribution valueDist;
+  return maker.mapVector<int64_t, double>(
+      kSize,
+      [&](auto /*i*/) { return kMapSize; },
+      [](auto /*i*/, auto j) { return j; },
+      [&](auto /*i*/, auto /*j*/) { return valueDist(gen); });
+}
+
+MapVectorPtr generateUpdate(
+    memory::MemoryPool* pool,
+    std::default_random_engine& gen,
+    const MapVector& base) {
+  constexpr int kMapSize = 5;
+  auto offsets = allocateIndices(base.size(), pool);
+  auto* rawOffsets = offsets->asMutable<vector_size_t>();
+  rawOffsets[0] = 0;
+  for (int i = 1; i < base.size(); ++i) {
+    rawOffsets[i] = rawOffsets[i - 1] + kMapSize;
+  }
+  auto sizes = allocateIndices(base.size(), pool);
+  auto* rawSizes = sizes->asMutable<vector_size_t>();
+  std::fill(rawSizes, rawSizes + base.size(), kMapSize);
+  int64_t keyCandidates[10];
+  std::iota(std::begin(keyCandidates), std::end(keyCandidates), 0);
+  auto keys = BaseVector::create<FlatVector<int64_t>>(
+      BIGINT(), kMapSize * base.size(), pool);
+  for (int i = 0; i < base.size(); ++i) {
+    std::shuffle(std::begin(keyCandidates), std::end(keyCandidates), gen);
+    for (int j = 0; j < kMapSize; ++j) {
+      keys->set(j + i * kMapSize, keyCandidates[j]);
+    }
+  }
+  test::VectorMaker maker(pool);
+  std::uniform_real_distribution valueDist;
+  auto values = maker.flatVector<double>(
+      kMapSize * base.size(), [&](auto /*i*/) { return valueDist(gen); });
+  return std::make_shared<MapVector>(
+      pool,
+      base.type(),
+      nullptr,
+      base.size(),
+      std::move(offsets),
+      std::move(sizes),
+      std::move(keys),
+      std::move(values));
+}
+
+} // namespace
+} // namespace facebook::velox
+
+int main(int argc, char* argv[]) {
+  using namespace facebook::velox;
+  folly::Init follyInit(&argc, &argv);
+  memory::MemoryManager::initialize({});
+  auto pool = memory::memoryManager()->addLeafPool();
+  std::default_random_engine gen(std::random_device{}());
+  auto base = generateBase(pool.get(), gen);
+  auto update = generateUpdate(pool.get(), gen, *base);
+
+  folly::addBenchmark(__FILE__, "int64 keys", [&] {
+    auto result = base->update({update}, true);
+    folly::doNotOptimizeAway(result);
+    return 1000;
+  });
+  folly::runBenchmarks();
+
+  return 0;
+}
diff --git a/velox/vector/tests/VectorTest.cpp b/velox/vector/tests/VectorTest.cpp
index f0bdd951c3625..2c26dffe1b72d 100644
--- a/velox/vector/tests/VectorTest.cpp
+++ b/velox/vector/tests/VectorTest.cpp
@@ -3647,5 +3647,84 @@ TEST_F(VectorTest, getLargeStringBuffer) {
   EXPECT_GE(buffer->capacity(), size);
 }
 
+TEST_F(VectorTest, mapUpdate) {
+  auto base = makeNullableMapVector<int64_t, int64_t>({
+      {{{1, 1}, {2, 1}}},
+      {{}},
+      {{{3, 1}}},
+      std::nullopt,
+      {{{4, 1}}},
+  });
+  auto update = makeNullableMapVector<int64_t, int64_t>({
+      {{{2, 2}, {3, 2}}},
+      {{{4, 2}}},
+      {{}},
+      {{{5, 2}}},
+      std::nullopt,
+  });
+  auto expected = makeNullableMapVector<int64_t, int64_t>({
+      {{{2, 2}, {3, 2}, {1, 1}}},
+      {{{4, 2}}},
+      {{{3, 1}}},
+      std::nullopt,
+      std::nullopt,
+  });
+  auto actual = base->update({update}, false);
+  ASSERT_EQ(actual->size(), expected->size());
+  for (int i = 0; i < actual->size(); ++i) {
+    ASSERT_TRUE(actual->equalValueAt(expected.get(), i, i));
+  }
+}
+
+TEST_F(VectorTest, mapUpdateRowKeyType) {
+  auto base = makeMapVector(
+      {0, 2},
+      makeRowVector({
+          makeFlatVector<int64_t>({1, 2}),
+          makeFlatVector<int64_t>({1, 2}),
+      }),
+      makeFlatVector<int64_t>({1, 1}));
+  auto update = makeMapVector(
+      {0, 2},
+      makeRowVector({
+          makeFlatVector<int64_t>({2, 3}),
+          makeFlatVector<int64_t>({2, 3}),
+      }),
+      makeFlatVector<int64_t>({2, 2}));
+  auto expected = makeMapVector(
+      {0, 3},
+      makeRowVector({
+          makeFlatVector<int64_t>({1, 2, 3}),
+          makeFlatVector<int64_t>({1, 2, 3}),
+      }),
+      makeFlatVector<int64_t>({1, 2, 2}));
+  auto actual = base->update({update}, false);
+  ASSERT_EQ(actual->size(), expected->size());
+  for (int i = 0; i < actual->size(); ++i) {
+    ASSERT_TRUE(actual->equalValueAt(expected.get(), i, i));
+  }
+}
+
+TEST_F(VectorTest, mapUpdateDeleteNullMapValue) {
+  auto base = makeNullableMapVector<int64_t, int64_t>({
+      {{{1, 1}, {2, 1}}},
+  });
+  auto update = makeNullableMapVector<int64_t, int64_t>({
+      {{{2, std::nullopt}, {3, 2}}},
+  });
+  auto expected = makeNullableMapVector<int64_t, int64_t>({
+      {{{1, 1}, {3, 2}}},
+  });
+  auto actual = base->update({update}, true);
+  ASSERT_EQ(actual->size(), expected->size());
+  for (int i = 0; i < actual->size(); ++i) {
+    ASSERT_TRUE(actual->equalValueAt(expected.get(), i, i));
+  }
+#ifndef NDEBUG
+  // No null map value is allowed in base.
+  ASSERT_THROW(update->update({base}, true), VeloxException);
+#endif
+}
+
 } // namespace
 } // namespace facebook::velox