diff --git a/velox/vector/fuzzer/CMakeLists.txt b/velox/vector/fuzzer/CMakeLists.txt
index 43b8cc83746d6..36964ee7f5a1e 100644
--- a/velox/vector/fuzzer/CMakeLists.txt
+++ b/velox/vector/fuzzer/CMakeLists.txt
@@ -12,15 +12,30 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-add_library(velox_vector_fuzzer GeneratorSpec.cpp Utils.cpp VectorFuzzer.cpp)
+add_library(velox_vector_fuzzer_util Utils.cpp)
 
 target_link_libraries(
-  velox_vector_fuzzer velox_type velox_vector)
+  velox_vector_fuzzer_util velox_vector)
+
+add_library(velox_vector_fuzzer GeneratorSpec.cpp VectorFuzzer.cpp)
+
+target_link_libraries(
+  velox_vector_fuzzer velox_type velox_vector velox_vector_fuzzer_util)
 if(CMAKE_CXX_COMPILER_ID MATCHES "Clang")
   target_compile_options(velox_vector_fuzzer
                          PRIVATE -Wno-deprecated-declarations)
 endif()
 
+add_library(velox_fuzzer_constrained_input_generators
+            ConstrainedGenerators.cpp ConstrainedVectorGenerator.cpp)
+
+target_link_libraries(
+  velox_fuzzer_constrained_input_generators
+  Folly::folly
+  velox_expression
+  velox_type
+  velox_vector_fuzzer_util)
+
 if(${VELOX_BUILD_TESTING})
   add_subdirectory(tests)
 endif()
diff --git a/velox/vector/fuzzer/ConstrainedGenerators.cpp b/velox/vector/fuzzer/ConstrainedGenerators.cpp
new file mode 100644
index 0000000000000..51583c5b9c7bb
--- /dev/null
+++ b/velox/vector/fuzzer/ConstrainedGenerators.cpp
@@ -0,0 +1,206 @@
+/*
+ * 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/fuzzer/ConstrainedGenerators.h"
+
+#include <boost/random/uniform_int_distribution.hpp>
+
+#include "velox/vector/fuzzer/Utils.h"
+
+namespace facebook::velox::fuzzer {
+
+// AbstractInputGenerator
+AbstractInputGenerator::AbstractInputGenerator(
+    size_t seed,
+    const TypePtr& type,
+    std::unique_ptr<AbstractInputGenerator>&& next,
+    double nullRatio)
+    : type_{type}, next_{std::move(next)}, nullRatio_{nullRatio} {
+  rng_.seed(seed);
+}
+
+// NotEqualConstrainedGenerator
+variant NotEqualConstrainedGenerator::generate() {
+  variant value;
+  do {
+    value = next_->generate();
+  } while (value == excludedValue_);
+  return value;
+}
+
+// SetConstrainedGenerator
+variant SetConstrainedGenerator::generate() {
+  const auto index =
+      boost::random::uniform_int_distribution<size_t>(0, set_.size() - 1)(rng_);
+  return set_[index];
+}
+
+// JsonInputGenerator
+folly::json::serialization_opts JsonInputGenerator::getSerializationOptions() {
+  folly::json::serialization_opts opts;
+  opts.allow_non_string_keys = true;
+  opts.allow_nan_inf = true;
+  if (makeRandomVariation_) {
+    opts.convert_int_keys = rand<bool>(rng_);
+    opts.pretty_formatting = rand<bool>(rng_);
+    opts.pretty_formatting_indent_width = rand<uint32_t>(rng_, 0, 4);
+    opts.encode_non_ascii = rand<bool>(rng_);
+    opts.allow_trailing_comma = rand<bool>(rng_);
+    opts.sort_keys = rand<bool>(rng_);
+    opts.skip_invalid_utf8 = rand<bool>(rng_);
+    opts.parse_numbers_as_strings = rand<bool>(rng_);
+  }
+  return opts;
+}
+
+variant JsonInputGenerator::generate() {
+  if (coinToss(rng_, nullRatio_)) {
+    return variant::null(type_->kind());
+  }
+
+  const auto object = objectGenerator_->generate();
+  const folly::dynamic jsonObject = convertVariantToDynamic(object);
+  const auto jsonString = folly::json::serialize(jsonObject, opts_);
+  if (makeRandomVariation_ && coinToss(rng_, 0.5)) {
+    makeRandomVariation(jsonString);
+  }
+  return variant(jsonString);
+}
+
+folly::dynamic JsonInputGenerator::convertVariantToDynamic(
+    const variant& object) {
+  if (object.isNull()) {
+    return folly::dynamic();
+  }
+
+  switch (object.kind()) {
+    case TypeKind::BOOLEAN:
+      return convertVariantToDynamicPrimitive<TypeKind::BOOLEAN>(object);
+    case TypeKind::TINYINT:
+      return convertVariantToDynamicPrimitive<TypeKind::TINYINT>(object);
+    case TypeKind::SMALLINT:
+      return convertVariantToDynamicPrimitive<TypeKind::SMALLINT>(object);
+    case TypeKind::INTEGER:
+      return convertVariantToDynamicPrimitive<TypeKind::INTEGER>(object);
+    case TypeKind::BIGINT:
+      return convertVariantToDynamicPrimitive<TypeKind::BIGINT>(object);
+    case TypeKind::REAL:
+      return convertVariantToDynamicPrimitive<TypeKind::REAL>(object);
+    case TypeKind::DOUBLE:
+      return convertVariantToDynamicPrimitive<TypeKind::DOUBLE>(object);
+    case TypeKind::VARCHAR:
+      return convertVariantToDynamicPrimitive<TypeKind::VARCHAR>(object);
+    case TypeKind::VARBINARY:
+      return convertVariantToDynamicPrimitive<TypeKind::VARBINARY>(object);
+    case TypeKind::TIMESTAMP:
+      return convertVariantToDynamicPrimitive<TypeKind::TIMESTAMP>(object);
+    case TypeKind::HUGEINT:
+      return convertVariantToDynamicPrimitive<TypeKind::HUGEINT>(object);
+    case TypeKind::ARRAY: {
+      folly::dynamic array = folly::dynamic::array;
+      for (const auto& element : object.value<TypeKind::ARRAY>()) {
+        array.push_back(convertVariantToDynamic(element));
+      }
+      return array;
+    }
+    case TypeKind::MAP: {
+      folly::dynamic map = folly::dynamic::object;
+      for (const auto& [key, value] : object.value<TypeKind::MAP>()) {
+        map[convertVariantToDynamic(key)] = convertVariantToDynamic(value);
+      }
+      return map;
+    }
+    case TypeKind::ROW: {
+      folly::dynamic array = folly::dynamic::array;
+      for (const auto& element : object.value<TypeKind::ROW>()) {
+        array.push_back(convertVariantToDynamic(element));
+      }
+      return array;
+    }
+    default:
+      VELOX_UNREACHABLE("Unsupported type");
+  }
+}
+
+std::vector<std::string> getControlCharacters() {
+  static std::vector<std::string> controlCharacters = {
+      "\x00",   "\x01",   "\x02",   "\x03",   "\x04",   "\x05",   "\x06",
+      "\x07",   "\x08",   "\x09",   "\x0A",   "\x0B",   "\x0C",   "\x0D",
+      "\x0E",   "\x0F",   "\x10",   "\x11",   "\x12",   "\x13",   "\x14",
+      "\x15",   "\x16",   "\x17",   "\x18",   "\x19",   "\x1A",   "\x1B",
+      "\x1C",   "\x1D",   "\x1E",   "\x1F",   "\x20",   "\x7F",   "\u0080",
+      "\u0081", "\u0082", "\u0083", "\u0084", "\u0085", "\u0086", "\u0087",
+      "\u0088", "\u0089", "\u008A", "\u008B", "\u008C", "\u008D", "\u008E",
+      "\u008F", "\u0090", "\u0091", "\u0092", "\u0093", "\u0094", "\u0095",
+      "\u0096", "\u0097", "\u0098", "\u0099", "\u009A", "\u009B", "\u009C",
+      "\u009D", "\u009E", "\u009F"};
+  return controlCharacters;
+};
+
+void JsonInputGenerator::makeRandomVariation(std::string json) {
+  if (coinToss(rng_, 0.1)) {
+    const auto controlCharacters = getControlCharacters();
+    const auto index = rand<uint32_t>(rng_, 0, controlCharacters.size() - 1);
+    const auto& controlCharacter = controlCharacters[index];
+    const auto indexToInsert = rand<uint32_t>(rng_, 0, json.size());
+    json.insert(indexToInsert, controlCharacter);
+  } else if (coinToss(rng_, 0.1)) {
+    const auto size = rand<uint32_t>(rng_, 0, json.size());
+    json.resize(size);
+  }
+}
+
+// Utility functions
+template <bool, TypeKind KIND>
+std::unique_ptr<AbstractInputGenerator> getRandomInputGeneratorPrimitive(
+    size_t seed,
+    const TypePtr& type,
+    double nullRatio) {
+  using T = typename TypeTraits<KIND>::NativeType;
+  std::unique_ptr<AbstractInputGenerator> generator =
+      std::make_unique<RandomInputGenerator<T>>(seed, type, nullRatio);
+  return generator;
+}
+
+std::unique_ptr<AbstractInputGenerator>
+getRandomInputGenerator(size_t seed, const TypePtr& type, double nullRatio) {
+  std::unique_ptr<AbstractInputGenerator> generator;
+  if (type->isPrimitiveType()) {
+    return VELOX_DYNAMIC_SCALAR_TEMPLATE_TYPE_DISPATCH(
+        getRandomInputGeneratorPrimitive,
+        false,
+        type->kind(),
+        seed,
+        type,
+        nullRatio);
+  } else if (type->isArray()) {
+    generator = std::make_unique<RandomInputGenerator<ArrayType>>(
+        seed, type, nullRatio);
+  } else if (type->isMap()) {
+    generator =
+        std::make_unique<RandomInputGenerator<MapType>>(seed, type, nullRatio);
+
+  } else if (type->isRow()) {
+    generator = std::make_unique<RandomInputGenerator<RowType>>(
+        seed,
+        type,
+        std::vector<std::unique_ptr<AbstractInputGenerator>>{},
+        nullRatio);
+  }
+  return generator;
+}
+
+} // namespace facebook::velox::fuzzer
diff --git a/velox/vector/fuzzer/ConstrainedGenerators.h b/velox/vector/fuzzer/ConstrainedGenerators.h
new file mode 100644
index 0000000000000..ec31ea70561e9
--- /dev/null
+++ b/velox/vector/fuzzer/ConstrainedGenerators.h
@@ -0,0 +1,389 @@
+/*
+ * 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.
+ */
+
+#pragma once
+
+#include <memory>
+
+#include "folly/json.h"
+
+#include "velox/type/Type.h"
+#include "velox/type/Variant.h"
+#include "velox/vector/fuzzer/Utils.h"
+
+namespace facebook::velox::fuzzer {
+
+using facebook::velox::variant;
+
+class AbstractInputGenerator {
+ public:
+  AbstractInputGenerator(
+      size_t seed,
+      const TypePtr& type,
+      std::unique_ptr<AbstractInputGenerator>&& next,
+      double nullRatio);
+
+  virtual ~AbstractInputGenerator() = default;
+
+  virtual variant generate() = 0;
+
+  TypePtr type() const {
+    return type_;
+  }
+
+ protected:
+  FuzzerGenerator rng_;
+
+  TypePtr type_;
+
+  std::unique_ptr<AbstractInputGenerator> next_;
+
+  double nullRatio_;
+};
+
+std::unique_ptr<AbstractInputGenerator>
+getRandomInputGenerator(size_t seed, const TypePtr& type, double nullRatio);
+
+template <typename T, typename Enabled = void>
+class RandomInputGenerator : public AbstractInputGenerator {
+ public:
+  RandomInputGenerator(size_t seed, const TypePtr& type, double nullRatio)
+      : AbstractInputGenerator(seed, type, nullptr, nullRatio) {}
+
+  ~RandomInputGenerator() override = default;
+
+  variant generate() override {
+    if (coinToss(rng_, nullRatio_)) {
+      return variant::null(type_->kind());
+    }
+
+    if (type_->isDate()) {
+      return variant(randDate(rng_));
+    }
+    return variant(rand<T>(rng_));
+  }
+};
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
+template <typename T>
+class RandomInputGenerator<T, std::enable_if_t<std::is_same_v<T, StringView>>>
+    : public AbstractInputGenerator {
+ public:
+  RandomInputGenerator<T, std::enable_if_t<std::is_same_v<T, StringView>>>(
+      size_t seed,
+      const TypePtr& type,
+      double nullRatio,
+      size_t maxLength = 20,
+      const std::vector<UTF8CharList>& encodings =
+          {UTF8CharList::ASCII,
+           UTF8CharList::UNICODE_CASE_SENSITIVE,
+           UTF8CharList::EXTENDED_UNICODE,
+           UTF8CharList::MATHEMATICAL_SYMBOLS})
+      : AbstractInputGenerator(seed, type, nullptr, nullRatio),
+        maxLength_{maxLength},
+        encodings_{encodings} {}
+
+  ~RandomInputGenerator<T, std::enable_if_t<std::is_same_v<T, StringView>>>()
+      override = default;
+
+  variant generate() override {
+    if (coinToss(rng_, nullRatio_)) {
+      return variant::null(type_->kind());
+    }
+
+    const auto length = rand<size_t>(rng_, 0, maxLength_);
+    std::wstring_convert<std::codecvt_utf8<char16_t>, char16_t> converter;
+    std::string buf;
+    return variant(randString(rng_, length, encodings_, buf, converter));
+  }
+
+ private:
+  const size_t maxLength_;
+
+  std::vector<UTF8CharList> encodings_;
+};
+#pragma GCC diagnostic pop
+
+template <typename T>
+class RandomInputGenerator<T, std::enable_if_t<std::is_same_v<T, ArrayType>>>
+    : public AbstractInputGenerator {
+ public:
+  RandomInputGenerator<T, std::enable_if_t<std::is_same_v<T, ArrayType>>>(
+      size_t seed,
+      const TypePtr& type,
+      double nullRatio,
+      size_t maxLength = 10,
+      std::unique_ptr<AbstractInputGenerator>&& elementGenerator = nullptr,
+      std::optional<size_t> containAtIndex = std::nullopt,
+      std::unique_ptr<AbstractInputGenerator>&& containGenerator = nullptr)
+      : AbstractInputGenerator(seed, type, nullptr, nullRatio),
+        maxLength_{maxLength},
+        elementGenerator_{
+            elementGenerator
+                ? std::move(elementGenerator)
+                : getRandomInputGenerator(seed, type->childAt(0), nullRatio)},
+        containAtIndex_{containAtIndex},
+        containGenerator_{std::move(containGenerator)} {}
+
+  ~RandomInputGenerator<T, std::enable_if_t<std::is_same_v<T, ArrayType>>>()
+      override = default;
+
+  variant generate() override {
+    if (coinToss(rng_, nullRatio_)) {
+      return variant::null(TypeKind::ARRAY);
+    }
+
+    const auto length = rand<size_t>(rng_, 0, maxLength_);
+    std::vector<variant> elements;
+    elements.reserve(length);
+    for (size_t i = 0; i < length; ++i) {
+      if UNLIKELY (containAtIndex_.has_value() && *containAtIndex_ == i) {
+        elements.push_back(containGenerator_->generate());
+      } else {
+        elements.push_back(elementGenerator_->generate());
+      }
+    }
+    return variant::array(elements);
+  }
+
+ private:
+  const size_t maxLength_;
+
+  std::unique_ptr<AbstractInputGenerator> elementGenerator_;
+
+  std::optional<size_t> containAtIndex_;
+
+  std::unique_ptr<AbstractInputGenerator> containGenerator_;
+};
+
+template <typename T>
+class RandomInputGenerator<T, std::enable_if_t<std::is_same_v<T, MapType>>>
+    : public AbstractInputGenerator {
+ public:
+  RandomInputGenerator<T, std::enable_if_t<std::is_same_v<T, MapType>>>(
+      size_t seed,
+      const TypePtr& type,
+      double nullRatio,
+      size_t maxLength = 10,
+      std::unique_ptr<AbstractInputGenerator>&& keyGenerator = nullptr,
+      std::unique_ptr<AbstractInputGenerator>&& valueGenerator = nullptr,
+      std::optional<size_t> containAtIndex = std::nullopt,
+      std::unique_ptr<AbstractInputGenerator>&& containKeyGenerator = nullptr,
+      std::unique_ptr<AbstractInputGenerator>&& containValueGenerator = nullptr)
+      : AbstractInputGenerator(seed, type, nullptr, nullRatio),
+        maxLength_{maxLength},
+        keyGenerator_{
+            keyGenerator
+                ? std::move(keyGenerator)
+                : getRandomInputGenerator(seed, type->childAt(0), 0.0)},
+        valueGenerator_{
+            valueGenerator
+                ? std::move(valueGenerator)
+                : getRandomInputGenerator(seed, type->childAt(1), nullRatio)},
+        containAtIndex_{containAtIndex},
+        containKeyGenerator_{std::move(containKeyGenerator)},
+        containValueGenerator_{std::move(containValueGenerator)} {}
+
+  ~RandomInputGenerator<T, std::enable_if_t<std::is_same_v<T, MapType>>>()
+      override = default;
+
+  variant generate() override {
+    if (coinToss(rng_, nullRatio_)) {
+      return variant::null(TypeKind::MAP);
+    }
+
+    const auto length = rand<size_t>(rng_, 0, maxLength_);
+    std::map<variant, variant> map;
+    for (size_t i = 0; i < length; ++i) {
+      if UNLIKELY (containAtIndex_.has_value() && *containAtIndex_ == i) {
+        map.emplace(
+            containKeyGenerator_->generate(),
+            containValueGenerator_->generate());
+      } else {
+        map.emplace(keyGenerator_->generate(), valueGenerator_->generate());
+      }
+    }
+    return variant::map(map);
+  }
+
+ private:
+  const size_t maxLength_;
+
+  std::unique_ptr<AbstractInputGenerator> keyGenerator_;
+
+  std::unique_ptr<AbstractInputGenerator> valueGenerator_;
+
+  std::optional<size_t> containAtIndex_;
+
+  std::unique_ptr<AbstractInputGenerator> containKeyGenerator_;
+
+  std::unique_ptr<AbstractInputGenerator> containValueGenerator_;
+};
+
+template <typename T>
+class RandomInputGenerator<T, std::enable_if_t<std::is_same_v<T, RowType>>>
+    : public AbstractInputGenerator {
+ public:
+  RandomInputGenerator<T, std::enable_if_t<std::is_same_v<T, RowType>>>(
+      size_t seed,
+      const TypePtr& type,
+      std::vector<std::unique_ptr<AbstractInputGenerator>> fieldGenerators,
+      double nullRatio)
+      : AbstractInputGenerator(seed, type, nullptr, nullRatio) {
+    const auto length = type->size();
+    fieldGenerators_ = std::move(fieldGenerators);
+    for (size_t i = 0; i < length; ++i) {
+      if (fieldGenerators_.size() <= i) {
+        fieldGenerators_.push_back(
+            getRandomInputGenerator(seed, type->childAt(i), nullRatio));
+      } else if (fieldGenerators_[i] == nullptr) {
+        fieldGenerators_[i] =
+            getRandomInputGenerator(seed, type->childAt(i), nullRatio);
+      }
+    }
+  }
+
+  ~RandomInputGenerator<T, std::enable_if_t<std::is_same_v<T, RowType>>>()
+      override = default;
+
+  variant generate() override {
+    if (coinToss(rng_, nullRatio_)) {
+      return variant::null(TypeKind::ROW);
+    }
+
+    const auto length = type_->size();
+    std::vector<variant> fields;
+    fields.reserve(length);
+    for (size_t i = 0; i < length; ++i) {
+      fields.push_back(fieldGenerators_[i]->generate());
+    }
+    return variant::row(fields);
+  }
+
+ private:
+  std::vector<std::unique_ptr<AbstractInputGenerator>> fieldGenerators_;
+};
+
+template <typename T, std::enable_if_t<std::is_arithmetic_v<T>, int> = 0>
+class RangeConstrainedGenerator : public AbstractInputGenerator {
+ public:
+  RangeConstrainedGenerator(
+      size_t seed,
+      const TypePtr& type,
+      double nullRatio,
+      T min,
+      T max)
+      : AbstractInputGenerator(seed, type, nullptr, nullRatio),
+        min_{min},
+        max_{max} {}
+
+  ~RangeConstrainedGenerator() override = default;
+
+  variant generate() override {
+    if (coinToss(rng_, nullRatio_)) {
+      return variant::null(type_->kind());
+    }
+    return variant(rand<T>(rng_, min_, max_));
+  }
+
+ private:
+  T min_;
+  T max_;
+};
+
+class NotEqualConstrainedGenerator : public AbstractInputGenerator {
+ public:
+  // nullRatio doesn't affect the data generation because it is 'next' that
+  // generates data.
+  NotEqualConstrainedGenerator(
+      size_t seed,
+      const TypePtr& type,
+      const variant& excludedValue,
+      std::unique_ptr<AbstractInputGenerator>&& next)
+      : AbstractInputGenerator(seed, type, std::move(next), 0.0),
+        excludedValue_{excludedValue} {}
+
+  ~NotEqualConstrainedGenerator() override = default;
+
+  variant generate() override;
+
+ private:
+  variant excludedValue_;
+};
+
+class SetConstrainedGenerator : public AbstractInputGenerator {
+ public:
+  // nullRatio doesn't affect the data generation because only variants in 'set'
+  // can be generated.
+  SetConstrainedGenerator(
+      size_t seed,
+      const TypePtr& type,
+      const std::vector<variant>& set)
+      : AbstractInputGenerator(seed, type, nullptr, 0.0), set_{set} {}
+
+  ~SetConstrainedGenerator() override = default;
+
+  variant generate() override;
+
+ private:
+  std::vector<variant> set_;
+};
+
+class JsonInputGenerator : public AbstractInputGenerator {
+ public:
+  JsonInputGenerator(
+      size_t seed,
+      const TypePtr& type,
+      double nullRatio,
+      std::unique_ptr<AbstractInputGenerator>&& objectGenerator,
+      bool makeRandomVariation = false)
+      : AbstractInputGenerator(seed, type, nullptr, nullRatio),
+        objectGenerator_{std::move(objectGenerator)},
+        makeRandomVariation_{makeRandomVariation},
+        opts_{getSerializationOptions()} {}
+
+  ~JsonInputGenerator() override = default;
+
+  variant generate() override;
+
+  const folly::json::serialization_opts& serializationOptions() const {
+    return opts_;
+  }
+
+ private:
+  template <TypeKind KIND>
+  folly::dynamic convertVariantToDynamicPrimitive(const variant& v) {
+    using T = typename TypeTraits<KIND>::DeepCopiedType;
+    VELOX_CHECK(v.isSet());
+    const T value = v.value<T>();
+    return folly::dynamic(value);
+  }
+
+  folly::dynamic convertVariantToDynamic(const variant& object);
+
+  void makeRandomVariation(std::string json);
+
+  folly::json::serialization_opts getSerializationOptions();
+
+  std::unique_ptr<AbstractInputGenerator> objectGenerator_;
+
+  bool makeRandomVariation_;
+
+  folly::json::serialization_opts opts_;
+};
+
+} // namespace facebook::velox::fuzzer
diff --git a/velox/vector/fuzzer/ConstrainedVectorGenerator.cpp b/velox/vector/fuzzer/ConstrainedVectorGenerator.cpp
new file mode 100644
index 0000000000000..72db3075f3ad7
--- /dev/null
+++ b/velox/vector/fuzzer/ConstrainedVectorGenerator.cpp
@@ -0,0 +1,147 @@
+/*
+ * 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/fuzzer/ConstrainedVectorGenerator.h"
+
+#include "velox/expression/VectorWriters.h"
+
+namespace facebook::velox::fuzzer {
+
+using exec::GenericWriter;
+using exec::VectorWriter;
+
+// static
+VectorPtr ConstrainedVectorGenerator::generateConstant(
+    const std::shared_ptr<AbstractInputGenerator>& customGenerator,
+    vector_size_t size,
+    memory::MemoryPool* pool) {
+  VELOX_CHECK_NOT_NULL(customGenerator);
+  VELOX_CHECK(customGenerator->type()->isPrimitiveType());
+
+  const auto& type = customGenerator->type();
+  const auto variant = customGenerator->generate();
+
+  return BaseVector::createConstant(type, variant, size, pool);
+}
+
+template <TypeKind KIND>
+void writeOne(const variant& v, GenericWriter& writer);
+template <>
+void writeOne<TypeKind::VARCHAR>(const variant& v, GenericWriter& writer);
+template <>
+void writeOne<TypeKind::VARBINARY>(const variant& v, GenericWriter& writer);
+template <>
+void writeOne<TypeKind::ARRAY>(const variant& v, GenericWriter& writer);
+template <>
+void writeOne<TypeKind::MAP>(const variant& v, GenericWriter& writer);
+template <>
+void writeOne<TypeKind::ROW>(const variant& v, GenericWriter& writer);
+
+template <TypeKind KIND>
+void writeOne(const variant& v, GenericWriter& writer) {
+  using T = typename TypeTraits<KIND>::NativeType;
+  writer.template castTo<T>() = v.value<KIND>();
+}
+
+template <>
+void writeOne<TypeKind::VARCHAR>(const variant& v, GenericWriter& writer) {
+  writer.template castTo<Varchar>() = v.value<TypeKind::VARCHAR>();
+}
+
+template <>
+void writeOne<TypeKind::VARBINARY>(const variant& v, GenericWriter& writer) {
+  writer.template castTo<Varbinary>() = v.value<TypeKind::VARBINARY>();
+}
+
+template <>
+void writeOne<TypeKind::ARRAY>(const variant& v, GenericWriter& writer) {
+  auto& writerTyped = writer.template castTo<Array<Any>>();
+  const auto& elements = v.array();
+  for (const auto& element : elements) {
+    if (element.isNull()) {
+      writerTyped.add_null();
+    } else {
+      VELOX_DYNAMIC_TYPE_DISPATCH(
+          writeOne, element.kind(), element, writerTyped.add_item());
+    }
+  }
+}
+
+template <>
+void writeOne<TypeKind::MAP>(const variant& v, GenericWriter& writer) {
+  auto& writerTyped = writer.template castTo<Map<Any, Any>>();
+  const auto& map = v.map();
+  for (const auto& pair : map) {
+    const auto& key = pair.first;
+    const auto& value = pair.second;
+    VELOX_CHECK(!key.isNull());
+    if (value.isNull()) {
+      VELOX_DYNAMIC_TYPE_DISPATCH(
+          writeOne, key.kind(), key, writerTyped.add_null());
+    } else {
+      auto writers = writerTyped.add_item();
+      VELOX_DYNAMIC_TYPE_DISPATCH(
+          writeOne, key.kind(), key, std::get<0>(writers));
+      VELOX_DYNAMIC_TYPE_DISPATCH(
+          writeOne, value.kind(), value, std::get<1>(writers));
+    }
+  }
+}
+
+template <>
+void writeOne<TypeKind::ROW>(const variant& v, GenericWriter& writer) {
+  auto& writerTyped = writer.template castTo<DynamicRow>();
+  const auto& elements = v.row();
+  column_index_t i = 0;
+  for (const auto& element : elements) {
+    if (element.isNull()) {
+      writerTyped.set_null_at(i);
+    } else {
+      VELOX_DYNAMIC_TYPE_DISPATCH(
+          writeOne, element.kind(), element, writerTyped.get_writer_at(i));
+    }
+    i++;
+  }
+}
+
+// static
+VectorPtr ConstrainedVectorGenerator::generateFlat(
+    const std::shared_ptr<AbstractInputGenerator>& customGenerator,
+    vector_size_t size,
+    memory::MemoryPool* pool) {
+  VELOX_CHECK_NOT_NULL(customGenerator);
+
+  VectorPtr result;
+  const auto& type = customGenerator->type();
+  BaseVector::ensureWritable(SelectivityVector(size), type, pool, result);
+  VectorWriter<Any> writer;
+  writer.init(*result);
+
+  for (auto i = 0; i < size; ++i) {
+    writer.setOffset(i);
+    const auto variant = customGenerator->generate();
+    if (variant.isNull()) {
+      writer.commitNull();
+    } else {
+      VELOX_DYNAMIC_TYPE_DISPATCH(
+          writeOne, type->kind(), variant, writer.current());
+      writer.commit(true);
+    }
+  }
+  return result;
+}
+
+} // namespace facebook::velox::fuzzer
diff --git a/velox/vector/fuzzer/ConstrainedVectorGenerator.h b/velox/vector/fuzzer/ConstrainedVectorGenerator.h
new file mode 100644
index 0000000000000..5a887f26b453a
--- /dev/null
+++ b/velox/vector/fuzzer/ConstrainedVectorGenerator.h
@@ -0,0 +1,38 @@
+/*
+ * 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.
+ */
+
+#pragma once
+
+#include "velox/vector/fuzzer/ConstrainedGenerators.h"
+
+namespace facebook::velox::fuzzer {
+
+class ConstrainedVectorGenerator {
+ public:
+  ConstrainedVectorGenerator() = delete;
+
+  static VectorPtr generateConstant(
+      const std::shared_ptr<AbstractInputGenerator>& customGenerator,
+      vector_size_t size,
+      memory::MemoryPool* pool);
+
+  static VectorPtr generateFlat(
+      const std::shared_ptr<AbstractInputGenerator>& customGenerator,
+      vector_size_t size,
+      memory::MemoryPool* pool);
+};
+
+} // namespace facebook::velox::fuzzer
diff --git a/velox/vector/fuzzer/Utils.cpp b/velox/vector/fuzzer/Utils.cpp
index 805fcf1063d73..178dd50dfef92 100644
--- a/velox/vector/fuzzer/Utils.cpp
+++ b/velox/vector/fuzzer/Utils.cpp
@@ -16,13 +16,129 @@
 
 #include "velox/vector/fuzzer/Utils.h"
 
-namespace facebook::velox::generator_spec_utils {
+namespace facebook::velox {
 
 bool coinToss(FuzzerGenerator& rng, double threshold) {
   static std::uniform_real_distribution<> dist(0.0, 1.0);
   return dist(rng) < threshold;
 }
 
+Timestamp randTimestamp(
+    FuzzerGenerator& rng,
+    FuzzerTimestampPrecision timestampPrecision) {
+  // Generate timestamps only in the valid range to avoid datetime functions,
+  // such as try_cast(varchar as timestamp), throwing VeloxRuntimeError in
+  // fuzzers.
+  constexpr int64_t min = -2'140'671'600;
+  constexpr int64_t max = 2'140'671'600;
+  constexpr int64_t microInSecond = 1'000'000;
+  constexpr int64_t millisInSecond = 1'000;
+  // DWRF requires nano to be in a certain range. Hardcode the value here to
+  // avoid the dependency on DWRF.
+  constexpr int64_t MAX_NANOS = 1'000'000'000;
+
+  switch (timestampPrecision) {
+    case FuzzerTimestampPrecision::kNanoSeconds:
+      return Timestamp(
+          rand<int64_t>(rng, min, max), (rand<int64_t>(rng) % MAX_NANOS));
+    case FuzzerTimestampPrecision::kMicroSeconds:
+      return Timestamp::fromMicros(
+          rand<int64_t>(rng, min, max) * microInSecond +
+          rand<int64_t>(rng, -microInSecond, microInSecond));
+    case FuzzerTimestampPrecision::kMilliSeconds:
+      return Timestamp::fromMillis(
+          rand<int64_t>(rng, min, max) * millisInSecond +
+          rand<int64_t>(rng, -millisInSecond, millisInSecond));
+    case FuzzerTimestampPrecision::kSeconds:
+      return Timestamp(rand<int64_t>(rng, min, max), 0);
+  }
+  return {}; // no-op.
+}
+
+int32_t randDate(FuzzerGenerator& rng) {
+  constexpr int64_t min = -24'450;
+  constexpr int64_t max = 24'450;
+  return rand<int32_t>(rng, min, max);
+}
+
+/// Unicode character ranges. Ensure the vector indexes match the UTF8CharList
+/// enum values.
+///
+/// Source: https://jrgraphix.net/research/unicode_blocks.php
+static const std::vector<std::vector<std::pair<char16_t, char16_t>>>
+    kUTFChatSets{
+        // UTF8CharList::ASCII
+        {
+            {33, 127}, // All ASCII printable chars.
+        },
+        // UTF8CharList::UNICODE_CASE_SENSITIVE
+        {
+            {u'\u0020', u'\u007F'}, // Basic Latin.
+            {u'\u0400', u'\u04FF'}, // Cyrillic.
+        },
+        // UTF8CharList::EXTENDED_UNICODE
+        {
+            {u'\u03F0', u'\u03FF'}, // Greek.
+            {u'\u0100', u'\u017F'}, // Latin Extended A.
+            {u'\u0600', u'\u06FF'}, // Arabic.
+            {u'\u0900', u'\u097F'}, // Devanagari.
+            {u'\u0600', u'\u06FF'}, // Hebrew.
+            {u'\u3040', u'\u309F'}, // Hiragana.
+            {u'\u2000', u'\u206F'}, // Punctuation.
+            {u'\u2070', u'\u209F'}, // Sub/Super Script.
+            {u'\u20A0', u'\u20CF'}, // Currency.
+        },
+        // UTF8CharList::MATHEMATICAL_SYMBOLS
+        {
+            {u'\u2200', u'\u22FF'}, // Math Operators.
+            {u'\u2150', u'\u218F'}, // Number Forms.
+            {u'\u25A0', u'\u25FF'}, // Geometric Shapes.
+            {u'\u27C0', u'\u27EF'}, // Math Symbols.
+            {u'\u2A00', u'\u2AFF'}, // Supplemental.
+        },
+    };
+
+FOLLY_ALWAYS_INLINE char16_t getRandomChar(
+    FuzzerGenerator& rng,
+    const std::vector<std::pair<char16_t, char16_t>>& charSet) {
+  const auto& chars = charSet.size() == 1
+      ? charSet.front()
+      : charSet[rand<uint32_t>(rng) % charSet.size()];
+  auto size = chars.second - chars.first;
+  auto inc = (rand<uint32_t>(rng) % size);
+  char16_t res = chars.first + inc;
+  return res;
+}
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
+std::string randString(
+    FuzzerGenerator& rng,
+    size_t length,
+    const std::vector<UTF8CharList>& encodings,
+    std::string& buf,
+    std::wstring_convert<std::codecvt_utf8<char16_t>, char16_t>& converter) {
+  buf.clear();
+  std::u16string wbuf;
+  wbuf.resize(length);
+
+  for (size_t i = 0; i < length; ++i) {
+    // First choose a random encoding from the list of input acceptable
+    // encodings.
+    VELOX_CHECK_GE(encodings.size(), 1);
+    const auto& encoding = (encodings.size() == 1)
+        ? encodings.front()
+        : encodings[rand<uint32_t>(rng) % encodings.size()];
+
+    wbuf[i] = getRandomChar(rng, kUTFChatSets[encoding]);
+  }
+  buf.append(converter.to_bytes(wbuf));
+  return buf;
+}
+#pragma GCC diagnostic pop
+
+namespace generator_spec_utils {
+
 vector_size_t getRandomIndex(FuzzerGenerator& rng, vector_size_t maxIndex) {
   std::uniform_int_distribution<vector_size_t> indexGenerator(
       0, maxIndex); // generates index in [0, maxIndex]
@@ -59,4 +175,6 @@ BufferPtr generateIndicesBuffer(
   return indices;
 }
 
-} // namespace facebook::velox::generator_spec_utils
+} // namespace generator_spec_utils
+
+} // namespace facebook::velox
diff --git a/velox/vector/fuzzer/Utils.h b/velox/vector/fuzzer/Utils.h
index 0248b08f942fa..f5371ad249e13 100644
--- a/velox/vector/fuzzer/Utils.h
+++ b/velox/vector/fuzzer/Utils.h
@@ -16,6 +16,13 @@
 
 #pragma once
 
+#include <codecvt>
+#include <random>
+
+#include <boost/random/uniform_01.hpp>
+#include <boost/random/uniform_int_distribution.hpp>
+#include <boost/random/uniform_real_distribution.hpp>
+
 #include "velox/vector/BaseVector.h"
 #include "velox/vector/NullsBuilder.h"
 
@@ -23,6 +30,20 @@ namespace facebook::velox {
 
 using FuzzerGenerator = std::mt19937;
 
+enum UTF8CharList {
+  ASCII = 0, // Ascii character set.
+  UNICODE_CASE_SENSITIVE = 1, // Unicode scripts that support case.
+  EXTENDED_UNICODE = 2, // Extended Unicode: Arabic, Devanagiri etc
+  MATHEMATICAL_SYMBOLS = 3 // Mathematical Symbols.
+};
+
+bool coinToss(FuzzerGenerator& rng, double threshold);
+
+struct DataSpec {
+  bool includeNaN;
+  bool includeInfinity;
+};
+
 enum class FuzzerTimestampPrecision : int8_t {
   kNanoSeconds = 0,
   kMicroSeconds = 1,
@@ -30,9 +51,114 @@ enum class FuzzerTimestampPrecision : int8_t {
   kSeconds = 3,
 };
 
-namespace generator_spec_utils {
+// Generate random values for the different supported types.
+template <typename T>
+inline T rand(FuzzerGenerator& rng, DataSpec /*dataSpec*/ = {false, false}) {
+  VELOX_NYI();
+}
 
-bool coinToss(FuzzerGenerator& rng, double threshold);
+template <>
+inline int8_t rand(FuzzerGenerator& rng, DataSpec /*dataSpec*/) {
+  return boost::random::uniform_int_distribution<int8_t>()(rng);
+}
+
+template <>
+inline int16_t rand(FuzzerGenerator& rng, DataSpec /*dataSpec*/) {
+  return boost::random::uniform_int_distribution<int16_t>()(rng);
+}
+
+template <>
+inline int32_t rand(FuzzerGenerator& rng, DataSpec /*dataSpec*/) {
+  return boost::random::uniform_int_distribution<int32_t>()(rng);
+}
+
+template <>
+inline int64_t rand(FuzzerGenerator& rng, DataSpec /*dataSpec*/) {
+  return boost::random::uniform_int_distribution<int64_t>()(rng);
+}
+
+template <>
+inline double rand(FuzzerGenerator& rng, DataSpec dataSpec) {
+  if (dataSpec.includeNaN && coinToss(rng, 0.05)) {
+    return std::nan("");
+  }
+
+  if (dataSpec.includeInfinity && coinToss(rng, 0.05)) {
+    return std::numeric_limits<double>::infinity();
+  }
+
+  return boost::random::uniform_01<double>()(rng);
+}
+
+template <>
+inline float rand(FuzzerGenerator& rng, DataSpec dataSpec) {
+  if (dataSpec.includeNaN && coinToss(rng, 0.05)) {
+    return std::nanf("");
+  }
+
+  if (dataSpec.includeInfinity && coinToss(rng, 0.05)) {
+    return std::numeric_limits<float>::infinity();
+  }
+
+  return boost::random::uniform_01<float>()(rng);
+}
+
+template <>
+inline bool rand(FuzzerGenerator& rng, DataSpec /*dataSpec*/) {
+  return boost::random::uniform_int_distribution<uint32_t>(0, 1)(rng);
+}
+
+template <>
+inline uint32_t rand(FuzzerGenerator& rng, DataSpec /*dataSpec*/) {
+  return boost::random::uniform_int_distribution<uint32_t>()(rng);
+}
+
+template <>
+inline uint64_t rand(FuzzerGenerator& rng, DataSpec /*dataSpec*/) {
+  return boost::random::uniform_int_distribution<uint64_t>()(rng);
+}
+
+template <>
+inline int128_t rand(FuzzerGenerator& rng, DataSpec /*dataSpec*/) {
+  return HugeInt::build(rand<int64_t>(rng), rand<uint64_t>(rng));
+}
+
+Timestamp randTimestamp(
+    FuzzerGenerator& rng,
+    FuzzerTimestampPrecision timestampPrecision);
+
+template <>
+inline Timestamp rand(FuzzerGenerator& rng, DataSpec /*dataSpec*/) {
+  // TODO: support other timestamp precisions.
+  return randTimestamp(rng, FuzzerTimestampPrecision::kMicroSeconds);
+}
+
+int32_t randDate(FuzzerGenerator& rng);
+
+template <
+    typename T,
+    typename std::enable_if_t<std::is_arithmetic_v<T>, int> = 0>
+inline T rand(FuzzerGenerator& rng, T min, T max) {
+  if constexpr (std::is_integral_v<T>) {
+    return boost::random::uniform_int_distribution<T>(min, max)(rng);
+  } else {
+    return boost::random::uniform_real_distribution<T>(min, max)(rng);
+  }
+}
+
+/// Generates a random string in buf with characters of encodings. Return buf at
+/// the end.
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
+std::string randString(
+    FuzzerGenerator& rng,
+    size_t length,
+    const std::vector<UTF8CharList>& encodings,
+    std::string& buf,
+    std::wstring_convert<std::codecvt_utf8<char16_t>, char16_t>& converter);
+#pragma GCC diagnostic pop
+
+namespace generator_spec_utils {
 
 vector_size_t getRandomIndex(FuzzerGenerator& rng, vector_size_t maxIndex);
 
diff --git a/velox/vector/fuzzer/VectorFuzzer.cpp b/velox/vector/fuzzer/VectorFuzzer.cpp
index 56cd03a27c895..8f89eb2a09a7e 100644
--- a/velox/vector/fuzzer/VectorFuzzer.cpp
+++ b/velox/vector/fuzzer/VectorFuzzer.cpp
@@ -27,15 +27,12 @@
 #include "velox/vector/FlatVector.h"
 #include "velox/vector/NullsBuilder.h"
 #include "velox/vector/VectorTypeUtils.h"
+#include "velox/vector/fuzzer/Utils.h"
 
 namespace facebook::velox {
 
 namespace {
 
-// DWRF requires nano to be in a certain range. Hardcode the value here to avoid
-// the dependency on DWRF.
-constexpr int64_t MAX_NANOS = 1'000'000'000;
-
 // Structure to help temporary changes to Options. This objects saves the
 // current state of the Options object, and restores it when it's destructed.
 // For instance, if you would like to temporarily disable nulls for a particular
@@ -62,116 +59,6 @@ struct ScopedOptions {
   VectorFuzzer::Options savedOpts;
 };
 
-// Generate random values for the different supported types.
-template <typename T>
-T rand(FuzzerGenerator& rng, DataSpec dataSpec = {false, false}) {
-  VELOX_NYI();
-}
-
-template <>
-int8_t rand(FuzzerGenerator& rng, DataSpec /*dataSpec*/) {
-  return boost::random::uniform_int_distribution<int8_t>()(rng);
-}
-
-template <>
-int16_t rand(FuzzerGenerator& rng, DataSpec /*dataSpec*/) {
-  return boost::random::uniform_int_distribution<int16_t>()(rng);
-}
-
-template <>
-int32_t rand(FuzzerGenerator& rng, DataSpec /*dataSpec*/) {
-  return boost::random::uniform_int_distribution<int32_t>()(rng);
-}
-
-template <>
-int64_t rand(FuzzerGenerator& rng, DataSpec /*dataSpec*/) {
-  return boost::random::uniform_int_distribution<int64_t>()(rng);
-}
-
-template <>
-double rand(FuzzerGenerator& rng, DataSpec dataSpec) {
-  if (dataSpec.includeNaN && coinToss(rng, 0.05)) {
-    return std::nan("");
-  }
-
-  if (dataSpec.includeInfinity && coinToss(rng, 0.05)) {
-    return std::numeric_limits<double>::infinity();
-  }
-
-  return boost::random::uniform_01<double>()(rng);
-}
-
-template <>
-float rand(FuzzerGenerator& rng, DataSpec dataSpec) {
-  if (dataSpec.includeNaN && coinToss(rng, 0.05)) {
-    return std::nanf("");
-  }
-
-  if (dataSpec.includeInfinity && coinToss(rng, 0.05)) {
-    return std::numeric_limits<float>::infinity();
-  }
-
-  return boost::random::uniform_01<float>()(rng);
-}
-
-template <>
-bool rand(FuzzerGenerator& rng, DataSpec /*dataSpec*/) {
-  return boost::random::uniform_int_distribution<uint32_t>(0, 1)(rng);
-}
-
-template <>
-uint32_t rand(FuzzerGenerator& rng, DataSpec /*dataSpec*/) {
-  return boost::random::uniform_int_distribution<uint32_t>()(rng);
-}
-
-template <>
-uint64_t rand(FuzzerGenerator& rng, DataSpec /*dataSpec*/) {
-  return boost::random::uniform_int_distribution<uint64_t>()(rng);
-}
-
-template <>
-int128_t rand(FuzzerGenerator& rng, DataSpec /*dataSpec*/) {
-  return HugeInt::build(rand<int64_t>(rng), rand<uint64_t>(rng));
-}
-
-template <typename T, typename std::enable_if_t<std::is_integral_v<T>, int> = 0>
-T rand(FuzzerGenerator& rng, T min, T max) {
-  return boost::random::uniform_int_distribution<T>(min, max)(rng);
-}
-
-Timestamp randTimestamp(FuzzerGenerator& rng, VectorFuzzer::Options opts) {
-  // Generate timestamps only in the valid range to avoid datetime functions,
-  // such as try_cast(varchar as timestamp), throwing VeloxRuntimeError in
-  // fuzzers.
-  constexpr int64_t min = -2'140'671'600;
-  constexpr int64_t max = 2'140'671'600;
-  constexpr int64_t microInSecond = 1'000'000;
-  constexpr int64_t millisInSecond = 1'000;
-
-  switch (opts.timestampPrecision) {
-    case VectorFuzzer::Options::TimestampPrecision::kNanoSeconds:
-      return Timestamp(
-          rand<int64_t>(rng, min, max), (rand<int64_t>(rng) % MAX_NANOS));
-    case VectorFuzzer::Options::TimestampPrecision::kMicroSeconds:
-      return Timestamp::fromMicros(
-          rand<int64_t>(rng, min, max) * microInSecond +
-          rand<int64_t>(rng, -microInSecond, microInSecond));
-    case VectorFuzzer::Options::TimestampPrecision::kMilliSeconds:
-      return Timestamp::fromMillis(
-          rand<int64_t>(rng, min, max) * millisInSecond +
-          rand<int64_t>(rng, -millisInSecond, millisInSecond));
-    case VectorFuzzer::Options::TimestampPrecision::kSeconds:
-      return Timestamp(rand<int64_t>(rng, min, max), 0);
-  }
-  return {}; // no-op.
-}
-
-int32_t randDate(FuzzerGenerator& rng) {
-  constexpr int64_t min = -24'450;
-  constexpr int64_t max = 24'450;
-  return rand<int32_t>(rng, min, max);
-}
-
 size_t getElementsVectorLength(
     const VectorFuzzer::Options& opts,
     vector_size_t size) {
@@ -196,43 +83,7 @@ int128_t randLongDecimal(const TypePtr& type, FuzzerGenerator& rng) {
   return rand<int128_t>(rng) % DecimalUtil::kPowersOfTen[precision];
 }
 
-/// Unicode character ranges. Ensure the vector indexes match the UTF8CharList
-/// enum values.
-///
-/// Source: https://jrgraphix.net/research/unicode_blocks.php
-const std::vector<std::vector<std::pair<char16_t, char16_t>>> kUTFChatSets{
-    // UTF8CharList::ASCII
-    {
-        {33, 127}, // All ASCII printable chars.
-    },
-    // UTF8CharList::UNICODE_CASE_SENSITIVE
-    {
-        {u'\u0020', u'\u007F'}, // Basic Latin.
-        {u'\u0400', u'\u04FF'}, // Cyrillic.
-    },
-    // UTF8CharList::EXTENDED_UNICODE
-    {
-        {u'\u03F0', u'\u03FF'}, // Greek.
-        {u'\u0100', u'\u017F'}, // Latin Extended A.
-        {u'\u0600', u'\u06FF'}, // Arabic.
-        {u'\u0900', u'\u097F'}, // Devanagari.
-        {u'\u0600', u'\u06FF'}, // Hebrew.
-        {u'\u3040', u'\u309F'}, // Hiragana.
-        {u'\u2000', u'\u206F'}, // Punctuation.
-        {u'\u2070', u'\u209F'}, // Sub/Super Script.
-        {u'\u20A0', u'\u20CF'}, // Currency.
-    },
-    // UTF8CharList::MATHEMATICAL_SYMBOLS
-    {
-        {u'\u2200', u'\u22FF'}, // Math Operators.
-        {u'\u2150', u'\u218F'}, // Number Forms.
-        {u'\u25A0', u'\u25FF'}, // Geometric Shapes.
-        {u'\u27C0', u'\u27EF'}, // Math Symbols.
-        {u'\u2A00', u'\u2AFF'}, // Supplemental.
-    },
-};
-
-FOLLY_ALWAYS_INLINE char16_t getRandomChar(
+/*FOLLY_ALWAYS_INLINE char16_t getRandomChar(
     FuzzerGenerator& rng,
     const std::vector<std::pair<char16_t, char16_t>>& charSet) {
   const auto& chars = charSet.size() == 1
@@ -242,7 +93,7 @@ FOLLY_ALWAYS_INLINE char16_t getRandomChar(
   auto inc = (rand<uint32_t>(rng) % size);
   char16_t res = chars.first + inc;
   return res;
-}
+}*/
 
 /// Generates a random string (string size and encoding are passed through
 /// Options). Returns a StringView which uses `buf` as the underlying buffer.
@@ -251,24 +102,11 @@ StringView randString(
     const VectorFuzzer::Options& opts,
     std::string& buf,
     std::wstring_convert<std::codecvt_utf8<char16_t>, char16_t>& converter) {
-  buf.clear();
-  std::u16string wbuf;
   const size_t stringLength = opts.stringVariableLength
       ? rand<uint32_t>(rng) % opts.stringLength
       : opts.stringLength;
-  wbuf.resize(stringLength);
-
-  for (size_t i = 0; i < stringLength; ++i) {
-    // First choose a random encoding from the list of input acceptable
-    // encodings.
-    const auto& encoding = (opts.charEncodings.size() == 1)
-        ? opts.charEncodings.front()
-        : opts.charEncodings[rand<uint32_t>(rng) % opts.charEncodings.size()];
-
-    wbuf[i] = getRandomChar(rng, kUTFChatSets[encoding]);
-  }
 
-  buf.append(converter.to_bytes(wbuf));
+  randString(rng, stringLength, opts.charEncodings, buf, converter);
   return StringView(buf);
 }
 
@@ -290,7 +128,7 @@ VectorPtr fuzzConstantPrimitiveImpl(
   }
   if constexpr (std::is_same_v<TCpp, Timestamp>) {
     return std::make_shared<ConstantVector<TCpp>>(
-        pool, size, false, type, randTimestamp(rng, opts));
+        pool, size, false, type, randTimestamp(rng, opts.timestampPrecision));
   } else if (type->isDate()) {
     return std::make_shared<ConstantVector<int32_t>>(
         pool, size, false, type, randDate(rng));
@@ -322,7 +160,7 @@ void fuzzFlatPrimitiveImpl(
     if constexpr (std::is_same_v<TCpp, StringView>) {
       flatVector->set(i, randString(rng, opts, strBuf, converter));
     } else if constexpr (std::is_same_v<TCpp, Timestamp>) {
-      flatVector->set(i, randTimestamp(rng, opts));
+      flatVector->set(i, randTimestamp(rng, opts.timestampPrecision));
     } else if constexpr (std::is_same_v<TCpp, int64_t>) {
       if (vector->type()->isShortDecimal()) {
         flatVector->set(i, randShortDecimal(vector->type(), rng));
diff --git a/velox/vector/fuzzer/VectorFuzzer.h b/velox/vector/fuzzer/VectorFuzzer.h
index 0cd9a510305c7..665039f34fee8 100644
--- a/velox/vector/fuzzer/VectorFuzzer.h
+++ b/velox/vector/fuzzer/VectorFuzzer.h
@@ -26,18 +26,6 @@
 
 namespace facebook::velox {
 
-enum UTF8CharList {
-  ASCII = 0, // Ascii character set.
-  UNICODE_CASE_SENSITIVE = 1, // Unicode scripts that support case.
-  EXTENDED_UNICODE = 2, // Extended Unicode: Arabic, Devanagiri etc
-  MATHEMATICAL_SYMBOLS = 3 // Mathematical Symbols.
-};
-
-struct DataSpec {
-  bool includeNaN;
-  bool includeInfinity;
-};
-
 const std::vector<TypePtr>& defaultScalarTypes();
 
 /// VectorFuzzer is a helper class that generates randomized vectors and their
diff --git a/velox/vector/fuzzer/tests/CMakeLists.txt b/velox/vector/fuzzer/tests/CMakeLists.txt
index 4b8fdb65f5d08..bee3271a5cb25 100644
--- a/velox/vector/fuzzer/tests/CMakeLists.txt
+++ b/velox/vector/fuzzer/tests/CMakeLists.txt
@@ -22,3 +22,21 @@ target_link_libraries(
   GTest::gtest
   GTest::gtest_main
   GTest::gmock)
+
+add_executable(velox_fuzzer_constrained_input_generators_test
+               ConstrainedGeneratorsTest.cpp)
+
+add_test(
+  NAME velox_fuzzer_constrained_input_generators_test
+  COMMAND velox_fuzzer_constrained_input_generators_test
+  WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR})
+
+target_link_libraries(
+  velox_fuzzer_constrained_input_generators_test
+  velox_fuzzer_constrained_input_generators
+  velox_presto_types
+  velox_type
+  velox_vector_test_lib
+  GTest::gtest
+  GTest::gtest_main
+  GTest::gmock)
diff --git a/velox/vector/fuzzer/tests/ConstrainedGeneratorsTest.cpp b/velox/vector/fuzzer/tests/ConstrainedGeneratorsTest.cpp
new file mode 100644
index 0000000000000..8d1dfc17a652f
--- /dev/null
+++ b/velox/vector/fuzzer/tests/ConstrainedGeneratorsTest.cpp
@@ -0,0 +1,375 @@
+/*
+ * 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/fuzzer/ConstrainedGenerators.h"
+
+#include <gtest/gtest.h>
+
+#include "velox/functions/prestosql/types/JsonType.h"
+#include "velox/type/Variant.h"
+#include "velox/vector/fuzzer/ConstrainedVectorGenerator.h"
+#include "velox/vector/tests/utils/VectorTestBase.h"
+
+namespace facebook::velox::fuzzer::test {
+
+class ConstrainedGeneratorsTest : public testing::Test,
+                                  public velox::test::VectorTestBase {
+ protected:
+  static void SetUpTestCase() {
+    memory::MemoryManager::testingSetInstance({});
+  }
+
+  template <TypeKind KIND>
+  void testRandomPrimitive(const TypePtr& type, bool testNull) {
+    VELOX_CHECK_EQ(type->kind(), KIND);
+    using T = typename TypeTraits<KIND>::NativeType;
+
+    std::unique_ptr<AbstractInputGenerator> generator =
+        std::make_unique<RandomInputGenerator<T>>(
+            0, type, testNull ? 1.0 : 0.0);
+    auto value = generator->generate();
+    if (testNull) {
+      EXPECT_FALSE(value.hasValue());
+    } else {
+      EXPECT_TRUE(value.hasValue());
+    }
+    EXPECT_EQ(value.kind(), KIND);
+  }
+
+  template <TypeKind KIND>
+  void testRandomComplex(const TypePtr& type, bool testNull) {
+    VELOX_CHECK_EQ(type->kind(), KIND);
+    using T = typename TypeTraits<KIND>::ImplType;
+
+    std::unique_ptr<AbstractInputGenerator> generator =
+        std::make_unique<RandomInputGenerator<T>>(
+            0, type, testNull ? 1.0 : 0.0);
+    auto value = generator->generate();
+    EXPECT_EQ(value.kind(), KIND);
+    if (testNull) {
+      EXPECT_FALSE(value.hasValue());
+    } else {
+      EXPECT_TRUE(value.hasValue());
+    }
+  }
+
+  template <typename T>
+  void testRangePrimitive(const TypePtr& type, T min, T max, bool testNull) {
+    std::unique_ptr<AbstractInputGenerator> generator =
+        std::make_unique<RangeConstrainedGenerator<T>>(
+            0, type, testNull ? 1.0 : 0.0, min, max);
+
+    const uint32_t kIterations = 1000;
+    const variant lower = variant(min);
+    const variant upper = variant(max);
+    for (uint32_t i = 0; i < kIterations; ++i) {
+      auto value = generator->generate();
+      EXPECT_EQ(value.kind(), type->kind());
+      if (testNull) {
+        EXPECT_FALSE(value.hasValue());
+      } else {
+        EXPECT_TRUE(value.hasValue());
+        EXPECT_TRUE(lower < value || lower == value);
+        EXPECT_TRUE(value < upper || value == upper);
+      }
+    }
+  }
+
+  template <typename T>
+  void testRangeInComplex(const TypePtr& type, T min, T max, bool testNull) {
+    EXPECT_TRUE(type->isArray() && type->childAt(0)->isPrimitiveType());
+    std::unique_ptr<AbstractInputGenerator> generator =
+        std::make_unique<RandomInputGenerator<ArrayType>>(
+            0,
+            type,
+            0.0,
+            1000,
+            std::make_unique<RangeConstrainedGenerator<T>>(
+                0, type, testNull ? 1.0 : 0.0, min, max));
+
+    const auto value = generator->generate();
+    EXPECT_EQ(value.kind(), TypeKind::ARRAY);
+    EXPECT_TRUE(value.hasValue());
+
+    const auto elements = value.array();
+    const variant lower = variant(min);
+    const variant upper = variant(max);
+    for (const auto& element : elements) {
+      if (testNull) {
+        EXPECT_FALSE(element.hasValue());
+      } else {
+        EXPECT_TRUE(element.hasValue());
+        EXPECT_TRUE(lower < element || lower == element);
+        EXPECT_TRUE(element < upper || element == upper);
+      }
+    }
+  }
+
+  template <TypeKind KIND, typename TValue>
+  void testNotEqualPrimitive(
+      const TypePtr& type,
+      const TValue& excludedValue,
+      bool testNull) {
+    VELOX_CHECK_EQ(type->kind(), KIND);
+    using T = typename TypeTraits<KIND>::NativeType;
+
+    variant excludedVariant{excludedValue};
+    std::unique_ptr<AbstractInputGenerator> generator =
+        std::make_unique<NotEqualConstrainedGenerator>(
+            0,
+            type,
+            excludedVariant,
+            std::make_unique<RandomInputGenerator<T>>(
+                0, type, testNull ? 1.0 : 0.0));
+
+    const uint32_t kIterations = 1000;
+    for (uint32_t i = 0; i < kIterations; ++i) {
+      auto value = generator->generate();
+      EXPECT_EQ(value.kind(), KIND);
+      if (testNull) {
+        EXPECT_FALSE(value.hasValue());
+      } else {
+        EXPECT_TRUE(value.hasValue());
+        EXPECT_NE(value, excludedVariant);
+      }
+    }
+  }
+
+  template <TypeKind KIND>
+  void testNotEqualComplex(
+      const TypePtr& type,
+      const variant& excludedVariant,
+      bool testNull) {
+    VELOX_CHECK_EQ(type->kind(), KIND);
+    using T = typename TypeTraits<KIND>::ImplType;
+
+    std::unique_ptr<AbstractInputGenerator> generator =
+        std::make_unique<NotEqualConstrainedGenerator>(
+            0,
+            type,
+            excludedVariant,
+            std::make_unique<RandomInputGenerator<T>>(
+                0, type, testNull ? 1.0 : 0.0));
+
+    const uint32_t kIterations = 1000;
+    for (uint32_t i = 0; i < kIterations; ++i) {
+      auto value = generator->generate();
+      EXPECT_EQ(value.kind(), KIND);
+      if (testNull) {
+        EXPECT_FALSE(value.hasValue());
+      } else {
+        EXPECT_TRUE(value.hasValue());
+        EXPECT_NE(value, excludedVariant);
+      }
+    }
+  }
+
+  template <TypeKind KIND, typename TSet>
+  void testSetPrimitive(const TypePtr& type, const TSet& setOfRawValues) {
+    VELOX_CHECK_EQ(type->kind(), KIND);
+    using T = typename TypeTraits<KIND>::NativeType;
+
+    const uint32_t kIterations = 1000;
+    std::vector<variant> variants;
+    for (const auto& value : setOfRawValues) {
+      variants.push_back(variant{value});
+    }
+    std::unique_ptr<AbstractInputGenerator> generator =
+        std::make_unique<SetConstrainedGenerator>(0, type, variants);
+
+    for (uint32_t i = 0; i < kIterations; ++i) {
+      auto value = generator->generate();
+      EXPECT_TRUE(value.hasValue());
+      EXPECT_EQ(value.kind(), KIND);
+      EXPECT_NE(setOfRawValues.count(value.value<KIND>()), 0);
+    }
+  }
+
+  template <TypeKind KIND>
+  void testSetComplex(
+      const TypePtr& type,
+      const std::vector<variant>& variants) {
+    VELOX_CHECK_EQ(type->kind(), KIND);
+    using T = typename TypeTraits<KIND>::ImplType;
+
+    std::set<variant> setOfVariants{variants.begin(), variants.end()};
+
+    std::unique_ptr<AbstractInputGenerator> generator =
+        std::make_unique<SetConstrainedGenerator>(0, type, variants);
+
+    const uint32_t kIterations = 1000;
+    for (uint32_t i = 0; i < kIterations; ++i) {
+      auto value = generator->generate();
+      EXPECT_TRUE(value.hasValue());
+      EXPECT_EQ(value.kind(), KIND);
+      EXPECT_NE(setOfVariants.count(value), 0);
+    }
+  }
+
+  template <TypeKind KIND>
+  void testGenerateVectorsPrimitive(
+      const TypePtr& type,
+      const variant& excludedValue) {
+    using T = typename TypeTraits<KIND>::NativeType;
+    const uint32_t kSize = 1000;
+    std::shared_ptr<AbstractInputGenerator> generator =
+        std::make_shared<NotEqualConstrainedGenerator>(
+            0,
+            type,
+            excludedValue,
+            std::make_unique<RandomInputGenerator<T>>(0, type, 0.5));
+    auto vector =
+        ConstrainedVectorGenerator::generateConstant(generator, kSize, pool());
+    EXPECT_EQ(vector->size(), kSize);
+    EXPECT_EQ(vector->typeKind(), KIND);
+    EXPECT_TRUE(vector->isConstantEncoding());
+    EXPECT_TRUE(
+        vector->isNullAt(0) ||
+        vector->as<ConstantVector<T>>()->valueAt(0) != excludedValue);
+
+    vector = ConstrainedVectorGenerator::generateFlat(generator, kSize, pool());
+    EXPECT_EQ(vector->size(), kSize);
+    EXPECT_EQ(vector->typeKind(), KIND);
+    EXPECT_TRUE(vector->isFlatEncoding());
+    bool hasNull = false;
+    for (auto i = 0; i < kSize; ++i) {
+      if (vector->isNullAt(i)) {
+        hasNull = true;
+      } else {
+        EXPECT_NE(vector->as<FlatVector<T>>()->valueAt(i), excludedValue);
+      }
+    }
+    EXPECT_TRUE(hasNull);
+  }
+
+  template <TypeKind KIND>
+  void testGenerateVectorsComplex(const TypePtr& type) {
+    using T = typename TypeTraits<KIND>::ImplType;
+    const uint32_t kSize = 1000;
+    std::shared_ptr<AbstractInputGenerator> generator =
+        std::make_shared<RandomInputGenerator<T>>(0, type, 0.5);
+    auto vector =
+        ConstrainedVectorGenerator::generateFlat(generator, kSize, pool());
+    EXPECT_EQ(vector->size(), kSize);
+    EXPECT_EQ(vector->type(), type);
+  }
+};
+
+TEST_F(ConstrainedGeneratorsTest, randomPrimitive) {
+  testRandomPrimitive<TypeKind::INTEGER>(INTEGER(), false);
+  testRandomPrimitive<TypeKind::VARCHAR>(VARCHAR(), false);
+
+  testRandomPrimitive<TypeKind::INTEGER>(INTEGER(), true);
+  testRandomPrimitive<TypeKind::VARCHAR>(VARCHAR(), true);
+}
+
+TEST_F(ConstrainedGeneratorsTest, randomComplex) {
+  testRandomComplex<TypeKind::ARRAY>(
+      ARRAY(MAP(VARCHAR(), ROW({BIGINT()}))), false);
+  testRandomComplex<TypeKind::ARRAY>(
+      ARRAY(MAP(VARCHAR(), ROW({BIGINT()}))), true);
+}
+
+TEST_F(ConstrainedGeneratorsTest, rangePrimitive) {
+  testRangePrimitive<int64_t>(BIGINT(), 1, 10, false);
+  testRangePrimitive<int64_t>(BIGINT(), 1, 10, true);
+
+  testRangePrimitive<float>(REAL(), 1.0, 10.0, false);
+  testRangePrimitive<float>(REAL(), 1.0, 10.0, true);
+}
+
+TEST_F(ConstrainedGeneratorsTest, rangeInComplex) {
+  testRangeInComplex<int64_t>(ARRAY(BIGINT()), 1, 10, false);
+  testRangeInComplex<int64_t>(ARRAY(BIGINT()), 1, 10, true);
+
+  testRangeInComplex<float>(ARRAY(REAL()), 1.0, 10.0, false);
+  testRangeInComplex<float>(ARRAY(REAL()), 1.0, 10.0, true);
+}
+
+TEST_F(ConstrainedGeneratorsTest, notEqPrimitive) {
+  testNotEqualPrimitive<TypeKind::TINYINT>(
+      TINYINT(), static_cast<int8_t>(1), false);
+  testNotEqualPrimitive<TypeKind::VARCHAR>(VARCHAR(), ""_sv, false);
+
+  testNotEqualPrimitive<TypeKind::TINYINT>(
+      TINYINT(), static_cast<int8_t>(1), true);
+  testNotEqualPrimitive<TypeKind::VARCHAR>(VARCHAR(), ""_sv, true);
+}
+
+TEST_F(ConstrainedGeneratorsTest, notEqComplex) {
+  auto excludedVariant = variant::array({variant::map(
+      {{variant{"1"}, variant::row({variant{static_cast<int32_t>(1)}})}})});
+  testNotEqualComplex<TypeKind::ARRAY>(
+      ARRAY(MAP(VARCHAR(), ROW({BIGINT()}))), excludedVariant, false);
+  testNotEqualComplex<TypeKind::ARRAY>(
+      ARRAY(MAP(VARCHAR(), ROW({BIGINT()}))), excludedVariant, true);
+}
+
+TEST_F(ConstrainedGeneratorsTest, setPrimitive) {
+  std::unordered_set<int32_t> integers{{1, 2, 3}};
+  testSetPrimitive<TypeKind::INTEGER>(INTEGER(), integers);
+
+  std::unordered_set<std::string> strings{{"1", "2", "3"}};
+  testSetPrimitive<TypeKind::VARCHAR>(VARCHAR(), strings);
+}
+
+TEST_F(ConstrainedGeneratorsTest, setComplex) {
+  std::vector<variant> variants{
+      variant::array({variant::map(
+          {{variant{"1"}, variant::row({variant{static_cast<int32_t>(1)}})}})}),
+      variant::array({variant::map(
+          {{variant{"2"},
+            variant::row({variant{static_cast<int32_t>(2)}})}})})};
+  testSetComplex<TypeKind::ARRAY>(
+      ARRAY(MAP(VARCHAR(), ROW({BIGINT()}))), variants);
+}
+
+TEST_F(ConstrainedGeneratorsTest, json) {
+  const TypePtr type = ARRAY(MAP(DOUBLE(), ROW({BIGINT()})));
+  std::unique_ptr<JsonInputGenerator> generator =
+      std::make_unique<JsonInputGenerator>(
+          0,
+          JSON(),
+          0.4,
+          std::make_unique<RandomInputGenerator<ArrayType>>(0, type, 0.4));
+
+  const uint32_t kIterations = 1000;
+  const auto& opts = generator->serializationOptions();
+  for (uint32_t i = 0; i < kIterations; ++i) {
+    auto value = generator->generate();
+    EXPECT_EQ(value.kind(), TypeKind::VARCHAR);
+    if (value.hasValue()) {
+      EXPECT_TRUE(value.hasValue());
+      folly::dynamic json;
+      auto jsonString = value.value<TypeKind::VARCHAR>();
+      EXPECT_NO_THROW(
+          json = folly::parseJson(value.value<TypeKind::VARCHAR>(), opts));
+      EXPECT_TRUE(json.isNull() || json.isArray());
+    }
+  }
+}
+
+TEST_F(ConstrainedGeneratorsTest, generateVectors) {
+  testGenerateVectorsPrimitive<TypeKind::BIGINT>(BIGINT(), variant(0));
+  testGenerateVectorsPrimitive<TypeKind::VARCHAR>(VARCHAR(), variant(""));
+
+  testGenerateVectorsComplex<TypeKind::ARRAY>(
+      ARRAY(ROW({MAP(VARCHAR(), BIGINT())})));
+  testGenerateVectorsComplex<TypeKind::MAP>(
+      MAP(ARRAY(BIGINT()), ROW({VARCHAR()})));
+}
+
+} // namespace facebook::velox::fuzzer::test