enhance: speed up search iterator stage 1 (#37947)

issue: #37548

Signed-off-by: Patrick Weizhi Xu <weizhi.xu@zilliz.com>

go.mod

@@ -64,6 +64,7 @@ require (
 	github.com/cenkalti/backoff/v4 v4.2.1
 	github.com/cockroachdb/redact v1.1.3
 	github.com/goccy/go-json v0.10.3
+	github.com/google/uuid v1.6.0
 	github.com/greatroar/blobloom v0.0.0-00010101000000-000000000000
 	github.com/hashicorp/golang-lru/v2 v2.0.7
 	github.com/jolestar/go-commons-pool/v2 v2.1.2
@@ -144,7 +145,6 @@ require (
 	github.com/golang/snappy v0.0.4 // indirect
 	github.com/google/flatbuffers v2.0.8+incompatible // indirect
 	github.com/google/s2a-go v0.1.7 // indirect
-	github.com/google/uuid v1.6.0 // indirect
 	github.com/googleapis/enterprise-certificate-proxy v0.3.2 // indirect
 	github.com/googleapis/gax-go/v2 v2.12.5 // indirect
 	github.com/gorilla/websocket v1.4.2 // indirect

internal/core/src/common/QueryInfo.h

@@ -24,6 +24,12 @@
 
 namespace milvus {
 
+struct SearchIteratorV2Info {
+    std::string token = "";
+    uint32_t batch_size = 0;
+    std::optional<float> last_bound = std::nullopt;
+};
+
 struct SearchInfo {
     int64_t topk_{0};
     int64_t group_size_{1};
@@ -36,6 +42,7 @@ struct SearchInfo {
     tracer::TraceContext trace_ctx_;
     bool materialized_view_involved = false;
     bool iterative_filter_execution = false;
+    std::optional<SearchIteratorV2Info> iterator_v2_info_ = std::nullopt;
 };
 
 using SearchInfoPtr = std::shared_ptr<SearchInfo>;

internal/core/src/index/Utils.cpp

@@ -362,4 +362,38 @@ ReadDataFromFD(int fd, void* buf, size_t size, size_t chunk_size) {
     }
 }
 
+bool
+CheckAndUpdateKnowhereRangeSearchParam(const SearchInfo& search_info,
+                                       const int64_t topk,
+                                       const MetricType& metric_type,
+                                       knowhere::Json& search_config) {
+    const auto radius =
+        index::GetValueFromConfig<float>(search_info.search_params_, RADIUS);
+    if (!radius.has_value()) {
+        return false;
+    }
+
+    search_config[RADIUS] = radius.value();
+    // `range_search_k` is only used as one of the conditions for iterator early termination.
+    // not gurantee to return exactly `range_search_k` results, which may be more or less.
+    // set it to -1 will return all results in the range.
+    search_config[knowhere::meta::RANGE_SEARCH_K] = topk;
+
+    const auto range_filter =
+        GetValueFromConfig<float>(search_info.search_params_, RANGE_FILTER);
+    if (range_filter.has_value()) {
+        search_config[RANGE_FILTER] = range_filter.value();
+        CheckRangeSearchParam(
+            search_config[RADIUS], search_config[RANGE_FILTER], metric_type);
+    }
+
+    const auto page_retain_order =
+        GetValueFromConfig<bool>(search_info.search_params_, PAGE_RETAIN_ORDER);
+    if (page_retain_order.has_value()) {
+        search_config[knowhere::meta::RETAIN_ITERATOR_ORDER] =
+            page_retain_order.value();
+    }
+    return true;
+}
+
 }  // namespace milvus::index

internal/core/src/index/Utils.h

@@ -30,6 +30,8 @@
 
 #include "common/Types.h"
 #include "common/FieldData.h"
+#include "common/QueryInfo.h"
+#include "common/RangeSearchHelper.h"
 #include "index/IndexInfo.h"
 #include "storage/Types.h"
 
@@ -147,4 +149,10 @@ AssembleIndexDatas(std::map<std::string, FieldDataChannelPtr>& index_datas,
 void
 ReadDataFromFD(int fd, void* buf, size_t size, size_t chunk_size = 0x7ffff000);
 
+bool
+CheckAndUpdateKnowhereRangeSearchParam(const SearchInfo& search_info,
+                                       const int64_t topk,
+                                       const MetricType& metric_type,
+                                       knowhere::Json& search_config);
+
 }  // namespace milvus::index

internal/core/src/index/VectorDiskIndex.cpp

@@ -266,32 +266,9 @@ VectorDiskAnnIndex<T>::Query(const DatasetPtr dataset,
     search_config[DISK_ANN_PREFIX_PATH] = local_index_path_prefix;
 
     auto final = [&] {
-        auto radius =
+        if (CheckAndUpdateKnowhereRangeSearchParam(
-            GetValueFromConfig<float>(search_info.search_params_, RADIUS);
+                search_info, topk, GetMetricType(), search_config)) {
-        if (radius.has_value()) {
-            search_config[RADIUS] = radius.value();
-            // `range_search_k` is only used as one of the conditions for iterator early termination.
-            // not gurantee to return exactly `range_search_k` results, which may be more or less.
-            // set it to -1 will return all results in the range.
-            search_config[knowhere::meta::RANGE_SEARCH_K] = topk;
-            auto range_filter = GetValueFromConfig<float>(
-                search_info.search_params_, RANGE_FILTER);
-            if (range_filter.has_value()) {
-                search_config[RANGE_FILTER] = range_filter.value();
-                CheckRangeSearchParam(search_config[RADIUS],
-                                      search_config[RANGE_FILTER],
-                                      GetMetricType());
-            }
-
-            auto page_retain_order = GetValueFromConfig<bool>(
-                search_info.search_params_, PAGE_RETAIN_ORDER);
-            if (page_retain_order.has_value()) {
-                search_config[knowhere::meta::RETAIN_ITERATOR_ORDER] =
-                    page_retain_order.value();
-            }
-
             auto res = index_.RangeSearch(dataset, search_config, bitset);
-
             if (!res.has_value()) {
                 PanicInfo(ErrorCode::UnexpectedError,
                           fmt::format("failed to range search: {}: {}",

internal/core/src/index/VectorMemIndex.cpp

@@ -380,16 +380,8 @@ VectorMemIndex<T>::Query(const DatasetPtr dataset,
     // TODO :: check dim of search data
     auto final = [&] {
         auto index_type = GetIndexType();
-        if (CheckKeyInConfig(search_conf, RADIUS)) {
+        if (CheckAndUpdateKnowhereRangeSearchParam(
-            if (CheckKeyInConfig(search_conf, RANGE_FILTER)) {
+                search_info, topk, GetMetricType(), search_conf)) {
-                CheckRangeSearchParam(search_conf[RADIUS],
-                                      search_conf[RANGE_FILTER],
-                                      GetMetricType());
-            }
-            // `range_search_k` is only used as one of the conditions for iterator early termination.
-            // not gurantee to return exactly `range_search_k` results, which may be more or less.
-            // set it to -1 will return all results in the range.
-            search_conf[knowhere::meta::RANGE_SEARCH_K] = topk;
             milvus::tracer::AddEvent("start_knowhere_index_range_search");
             auto res = index_.RangeSearch(dataset, search_conf, bitset);
             milvus::tracer::AddEvent("finish_knowhere_index_range_search");

internal/core/src/query/CachedSearchIterator.cpp

@@ -0,0 +1,362 @@
+// Copyright (C) 2019-2024 Zilliz. All rights reserved.
+//
+// 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 "query/CachedSearchIterator.h"
+#include "query/SearchBruteForce.h"
+#include <algorithm>
+
+namespace milvus::query {
+
+CachedSearchIterator::CachedSearchIterator(
+    const milvus::index::VectorIndex& index,
+    const knowhere::DataSetPtr& query_ds,
+    const SearchInfo& search_info,
+    const BitsetView& bitset) {
+    if (query_ds == nullptr) {
+        PanicInfo(ErrorCode::UnexpectedError,
+                  "Query dataset is nullptr, cannot initialize iterator");
+    }
+    nq_ = query_ds->GetRows();
+    Init(search_info);
+
+    auto search_json = index.PrepareSearchParams(search_info);
+    index::CheckAndUpdateKnowhereRangeSearchParam(
+        search_info, batch_size_, index.GetMetricType(), search_json);
+
+    auto expected_iterators =
+        index.VectorIterators(query_ds, search_json, bitset);
+    if (expected_iterators.has_value()) {
+        iterators_ = std::move(expected_iterators.value());
+    } else {
+        PanicInfo(ErrorCode::UnexpectedError,
+                  "Failed to create iterators from index");
+    }
+}
+
+CachedSearchIterator::CachedSearchIterator(
+    const dataset::SearchDataset& query_ds,
+    const dataset::RawDataset& raw_ds,
+    const SearchInfo& search_info,
+    const std::map<std::string, std::string>& index_info,
+    const BitsetView& bitset,
+    const milvus::DataType& data_type) {
+    nq_ = query_ds.num_queries;
+    Init(search_info);
+
+    auto expected_iterators = GetBruteForceSearchIterators(
+        query_ds, raw_ds, search_info, index_info, bitset, data_type);
+    if (expected_iterators.has_value()) {
+        iterators_ = std::move(expected_iterators.value());
+    } else {
+        PanicInfo(ErrorCode::UnexpectedError,
+                  "Failed to create iterators from index");
+    }
+}
+
+void
+CachedSearchIterator::InitializeChunkedIterators(
+    const dataset::SearchDataset& query_ds,
+    const SearchInfo& search_info,
+    const std::map<std::string, std::string>& index_info,
+    const BitsetView& bitset,
+    const milvus::DataType& data_type,
+    const GetChunkDataFunc& get_chunk_data) {
+    int64_t offset = 0;
+    chunked_heaps_.resize(nq_);
+    for (int64_t chunk_id = 0; chunk_id < num_chunks_; ++chunk_id) {
+        auto [chunk_data, chunk_size] = get_chunk_data(chunk_id);
+        auto sub_data = query::dataset::RawDataset{
+            offset, query_ds.dim, chunk_size, chunk_data};
+
+        auto expected_iterators = GetBruteForceSearchIterators(
+            query_ds, sub_data, search_info, index_info, bitset, data_type);
+        if (expected_iterators.has_value()) {
+            auto& chunk_iterators = expected_iterators.value();
+            iterators_.insert(iterators_.end(),
+                              std::make_move_iterator(chunk_iterators.begin()),
+                              std::make_move_iterator(chunk_iterators.end()));
+        } else {
+            PanicInfo(ErrorCode::UnexpectedError,
+                      "Failed to create iterators from index");
+        }
+        offset += chunk_size;
+    }
+}
+
+CachedSearchIterator::CachedSearchIterator(
+    const dataset::SearchDataset& query_ds,
+    const segcore::VectorBase* vec_data,
+    const int64_t row_count,
+    const SearchInfo& search_info,
+    const std::map<std::string, std::string>& index_info,
+    const BitsetView& bitset,
+    const milvus::DataType& data_type) {
+    if (vec_data == nullptr) {
+        PanicInfo(ErrorCode::UnexpectedError,
+                  "Vector data is nullptr, cannot initialize iterator");
+    }
+
+    if (row_count <= 0) {
+        PanicInfo(ErrorCode::UnexpectedError,
+                  "Number of rows is 0, cannot initialize iterator");
+    }
+
+    const int64_t vec_size_per_chunk = vec_data->get_size_per_chunk();
+    num_chunks_ = upper_div(row_count, vec_size_per_chunk);
+    nq_ = query_ds.num_queries;
+    Init(search_info);
+
+    iterators_.reserve(nq_ * num_chunks_);
+    InitializeChunkedIterators(
+        query_ds,
+        search_info,
+        index_info,
+        bitset,
+        data_type,
+        [&vec_data, vec_size_per_chunk, row_count](
+            int64_t chunk_id) -> std::pair<const void*, int64_t> {
+            const auto chunk_data = vec_data->get_chunk_data(chunk_id);
+            int64_t chunk_size = std::min(
+                vec_size_per_chunk, row_count - chunk_id * vec_size_per_chunk);
+            return {chunk_data, chunk_size};
+        });
+}
+
+CachedSearchIterator::CachedSearchIterator(
+    const std::shared_ptr<ChunkedColumnBase>& column,
+    const dataset::SearchDataset& query_ds,
+    const SearchInfo& search_info,
+    const std::map<std::string, std::string>& index_info,
+    const BitsetView& bitset,
+    const milvus::DataType& data_type) {
+    if (column == nullptr) {
+        PanicInfo(ErrorCode::UnexpectedError,
+                  "Column is nullptr, cannot initialize iterator");
+    }
+
+    num_chunks_ = column->num_chunks();
+    nq_ = query_ds.num_queries;
+    Init(search_info);
+
+    iterators_.reserve(nq_ * num_chunks_);
+    InitializeChunkedIterators(
+        query_ds,
+        search_info,
+        index_info,
+        bitset,
+        data_type,
+        [&column](int64_t chunk_id) {
+            const char* chunk_data = column->Data(chunk_id);
+            int64_t chunk_size = column->chunk_row_nums(chunk_id);
+            return std::make_pair(static_cast<const void*>(chunk_data),
+                                  chunk_size);
+        });
+}
+
+void
+CachedSearchIterator::NextBatch(const SearchInfo& search_info,
+                                SearchResult& search_result) {
+    if (iterators_.empty()) {
+        return;
+    }
+
+    if (iterators_.size() != nq_ * num_chunks_) {
+        PanicInfo(ErrorCode::UnexpectedError,
+                  "Iterator size mismatch, expect %d, but got %d",
+                  nq_ * num_chunks_,
+                  iterators_.size());
+    }
+
+    ValidateSearchInfo(search_info);
+
+    search_result.total_nq_ = nq_;
+    search_result.unity_topK_ = batch_size_;
+    search_result.seg_offsets_.resize(nq_ * batch_size_);
+    search_result.distances_.resize(nq_ * batch_size_);
+
+    for (size_t query_idx = 0; query_idx < nq_; ++query_idx) {
+        auto rst = GetBatchedNextResults(query_idx, search_info);
+        WriteSingleQuerySearchResult(
+            search_result, query_idx, rst, search_info.round_decimal_);
+    }
+}
+
+void
+CachedSearchIterator::ValidateSearchInfo(const SearchInfo& search_info) {
+    if (!search_info.iterator_v2_info_.has_value()) {
+        PanicInfo(ErrorCode::UnexpectedError,
+                  "Iterator v2 SearchInfo is not set");
+    }
+
+    auto iterator_v2_info = search_info.iterator_v2_info_.value();
+    if (iterator_v2_info.batch_size != batch_size_) {
+        PanicInfo(ErrorCode::UnexpectedError,
+                  "Batch size mismatch, expect %d, but got %d",
+                  batch_size_,
+                  iterator_v2_info.batch_size);
+    }
+}
+
+std::optional<CachedSearchIterator::DisIdPair>
+CachedSearchIterator::GetNextValidResult(
+    const size_t iterator_idx,
+    const std::optional<float>& last_bound,
+    const std::optional<float>& radius,
+    const std::optional<float>& range_filter) {
+    auto& iterator = iterators_[iterator_idx];
+    while (iterator->HasNext()) {
+        auto result = ConvertIteratorResult(iterator->Next());
+        if (IsValid(result, last_bound, radius, range_filter)) {
+            return result;
+        }
+    }
+    return std::nullopt;
+}
+
+// TODO: Optimize this method
+void
+CachedSearchIterator::MergeChunksResults(
+    size_t query_idx,
+    const std::optional<float>& last_bound,
+    const std::optional<float>& radius,
+    const std::optional<float>& range_filter,
+    std::vector<DisIdPair>& rst) {
+    auto& heap = chunked_heaps_[query_idx];
+
+    if (heap.empty()) {
+        for (size_t chunk_id = 0; chunk_id < num_chunks_; ++chunk_id) {
+            const size_t iterator_idx = query_idx + chunk_id * nq_;
+            if (auto next_result = GetNextValidResult(
+                    iterator_idx, last_bound, radius, range_filter);
+                next_result.has_value()) {
+                heap.emplace(iterator_idx, next_result.value());
+            }
+        }
+    }
+
+    while (!heap.empty() && rst.size() < batch_size_) {
+        const auto [iterator_idx, cur_rst] = heap.top();
+        heap.pop();
+
+        // last_bound may change between NextBatch calls, discard any invalid results
+        if (!IsValid(cur_rst, last_bound, radius, range_filter)) {
+            continue;
+        }
+        rst.emplace_back(cur_rst);
+
+        if (auto next_result = GetNextValidResult(
+                iterator_idx, last_bound, radius, range_filter);
+            next_result.has_value()) {
+            heap.emplace(iterator_idx, next_result.value());
+        }
+    }
+}
+
+std::vector<CachedSearchIterator::DisIdPair>
+CachedSearchIterator::GetBatchedNextResults(size_t query_idx,
+                                            const SearchInfo& search_info) {
+    auto last_bound = ConvertIncomingDistance(
+        search_info.iterator_v2_info_.value().last_bound);
+    auto radius = ConvertIncomingDistance(
+        index::GetValueFromConfig<float>(search_info.search_params_, RADIUS));
+    auto range_filter =
+        ConvertIncomingDistance(index::GetValueFromConfig<float>(
+            search_info.search_params_, RANGE_FILTER));
+
+    std::vector<DisIdPair> rst;
+    rst.reserve(batch_size_);
+
+    if (num_chunks_ == 1) {
+        auto& iterator = iterators_[query_idx];
+        while (iterator->HasNext() && rst.size() < batch_size_) {
+            auto result = ConvertIteratorResult(iterator->Next());
+            if (IsValid(result, last_bound, radius, range_filter)) {
+                rst.emplace_back(result);
+            }
+        }
+    } else {
+        MergeChunksResults(query_idx, last_bound, radius, range_filter, rst);
+    }
+    std::sort(rst.begin(), rst.end());
+    if (sign_ == -1) {
+        std::for_each(rst.begin(), rst.end(), [this](DisIdPair& x) {
+            x.first = x.first * sign_;
+        });
+    }
+    while (rst.size() < batch_size_) {
+        rst.emplace_back(1.0f / 0.0f, -1);
+    }
+    return rst;
+}
+
+void
+CachedSearchIterator::WriteSingleQuerySearchResult(
+    SearchResult& search_result,
+    const size_t idx,
+    std::vector<DisIdPair>& rst,
+    const int64_t round_decimal) {
+    const float multiplier = pow(10.0, round_decimal);
+
+    std::transform(rst.begin(),
+                   rst.end(),
+                   search_result.distances_.begin() + idx * batch_size_,
+                   [multiplier, round_decimal](DisIdPair& x) {
+                       if (round_decimal != -1) {
+                           x.first =
+                               std::round(x.first * multiplier) / multiplier;
+                       }
+                       return x.first;
+                   });
+
+    std::transform(rst.begin(),
+                   rst.end(),
+                   search_result.seg_offsets_.begin() + idx * batch_size_,
+                   [](const DisIdPair& x) { return x.second; });
+}
+
+void
+CachedSearchIterator::Init(const SearchInfo& search_info) {
+    if (!search_info.iterator_v2_info_.has_value()) {
+        PanicInfo(ErrorCode::UnexpectedError,
+                  "Iterator v2 info is not set, cannot initialize iterator");
+    }
+
+    auto iterator_v2_info = search_info.iterator_v2_info_.value();
+    if (iterator_v2_info.batch_size == 0) {
+        PanicInfo(ErrorCode::UnexpectedError,
+                  "Batch size is 0, cannot initialize iterator");
+    }
+    batch_size_ = iterator_v2_info.batch_size;
+
+    if (search_info.metric_type_.empty()) {
+        PanicInfo(ErrorCode::UnexpectedError,
+                  "Metric type is empty, cannot initialize iterator");
+    }
+    if (PositivelyRelated(search_info.metric_type_)) {
+        sign_ = -1;
+    } else {
+        sign_ = 1;
+    }
+
+    if (nq_ == 0) {
+        PanicInfo(ErrorCode::UnexpectedError,
+                  "Number of queries is 0, cannot initialize iterator");
+    }
+
+    // disable multi-query for now
+    if (nq_ > 1) {
+        PanicInfo(
+            ErrorCode::UnexpectedError,
+            "Number of queries is greater than 1, cannot initialize iterator");
+    }
+}
+
+}  // namespace milvus::query

internal/core/src/query/CachedSearchIterator.h

@@ -0,0 +1,182 @@
+// Copyright (C) 2019-2024 Zilliz. All rights reserved.
+//
+// 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 <utility>
+#include "common/BitsetView.h"
+#include "common/QueryInfo.h"
+#include "common/QueryResult.h"
+#include "query/helper.h"
+#include "segcore/ConcurrentVector.h"
+#include "index/VectorIndex.h"
+
+namespace milvus::query {
+
+// This class is used to cache the search results from Knowhere
+// search iterators and filter the results based on the last_bound,
+// radius and range_filter.
+// It provides a number of constructors to support different scenarios,
+// including growing/sealed, chunked/non-chunked.
+//
+// It does not care about TopK in search_info
+// The topk in SearchResult will be set to the batch_size for compatibility
+//
+// TODO: introduce the pool of results in the near future
+// TODO: replace VectorIterator class
+class CachedSearchIterator {
+ public:
+    // For sealed segment with vector index
+    CachedSearchIterator(const milvus::index::VectorIndex& index,
+                         const knowhere::DataSetPtr& dataset,
+                         const SearchInfo& search_info,
+                         const BitsetView& bitset);
+
+    // For sealed segment, BF
+    CachedSearchIterator(const dataset::SearchDataset& dataset,
+                         const dataset::RawDataset& raw_ds,
+                         const SearchInfo& search_info,
+                         const std::map<std::string, std::string>& index_info,
+                         const BitsetView& bitset,
+                         const milvus::DataType& data_type);
+
+    // For growing segment with chunked data, BF
+    CachedSearchIterator(const dataset::SearchDataset& dataset,
+                         const segcore::VectorBase* vec_data,
+                         const int64_t row_count,
+                         const SearchInfo& search_info,
+                         const std::map<std::string, std::string>& index_info,
+                         const BitsetView& bitset,
+                         const milvus::DataType& data_type);
+
+    // For sealed segment with chunked data, BF
+    CachedSearchIterator(const std::shared_ptr<ChunkedColumnBase>& column,
+                         const dataset::SearchDataset& dataset,
+                         const SearchInfo& search_info,
+                         const std::map<std::string, std::string>& index_info,
+                         const BitsetView& bitset,
+                         const milvus::DataType& data_type);
+
+    // This method fetches the next batch of search results based on the provided search information
+    // and updates the search_result object with the new batch of results.
+    void
+    NextBatch(const SearchInfo& search_info, SearchResult& search_result);
+
+    // Disable copy and move
+    CachedSearchIterator(const CachedSearchIterator&) = delete;
+    CachedSearchIterator&
+    operator=(const CachedSearchIterator&) = delete;
+    CachedSearchIterator(CachedSearchIterator&&) = delete;
+    CachedSearchIterator&
+    operator=(CachedSearchIterator&&) = delete;
+
+ private:
+    using DisIdPair = std::pair<float, int64_t>;
+    using IterIdx = size_t;
+    using IterIdDisIdPair = std::pair<IterIdx, DisIdPair>;
+    using GetChunkDataFunc =
+        std::function<std::pair<const void*, int64_t>(int64_t)>;
+
+    int64_t batch_size_ = 0;
+    std::vector<knowhere::IndexNode::IteratorPtr> iterators_;
+    int8_t sign_ = 1;
+    size_t num_chunks_ = 1;
+    size_t nq_ = 0;
+
+    struct IterIdDisIdPairComparator {
+        bool
+        operator()(const IterIdDisIdPair& lhs, const IterIdDisIdPair& rhs) {
+            if (lhs.second.first == rhs.second.first) {
+                return lhs.second.second > rhs.second.second;
+            }
+            return lhs.second.first > rhs.second.first;
+        }
+    };
+    std::vector<std::priority_queue<IterIdDisIdPair,
+                                    std::vector<IterIdDisIdPair>,
+                                    IterIdDisIdPairComparator>>
+        chunked_heaps_;
+
+    inline bool
+    IsValid(const DisIdPair& result,
+            const std::optional<float>& last_bound,
+            const std::optional<float>& radius,
+            const std::optional<float>& range_filter) {
+        const float dist = result.first;
+        const bool is_valid =
+            !last_bound.has_value() || dist > last_bound.value();
+
+        if (!radius.has_value()) {
+            return is_valid;
+        }
+
+        if (!range_filter.has_value()) {
+            return is_valid && dist < radius.value();
+        }
+
+        return is_valid && dist < radius.value() &&
+               dist >= range_filter.value();
+    }
+
+    inline DisIdPair
+    ConvertIteratorResult(const std::pair<int64_t, float>& iter_rst) {
+        DisIdPair rst;
+        rst.first = iter_rst.second * sign_;
+        rst.second = iter_rst.first;
+        return rst;
+    }
+
+    inline std::optional<float>
+    ConvertIncomingDistance(std::optional<float> dist) {
+        if (dist.has_value()) {
+            dist = dist.value() * sign_;
+        }
+        return dist;
+    }
+
+    std::optional<DisIdPair>
+    GetNextValidResult(size_t iterator_idx,
+                       const std::optional<float>& last_bound,
+                       const std::optional<float>& radius,
+                       const std::optional<float>& range_filter);
+
+    void
+    MergeChunksResults(size_t query_idx,
+                       const std::optional<float>& last_bound,
+                       const std::optional<float>& radius,
+                       const std::optional<float>& range_filter,
+                       std::vector<DisIdPair>& rst);
+
+    void
+    ValidateSearchInfo(const SearchInfo& search_info);
+
+    std::vector<DisIdPair>
+    GetBatchedNextResults(size_t query_idx, const SearchInfo& search_info);
+
+    void
+    WriteSingleQuerySearchResult(SearchResult& search_result,
+                                 const size_t idx,
+                                 std::vector<DisIdPair>& rst,
+                                 const int64_t round_decimal);
+
+    void
+    Init(const SearchInfo& search_info);
+
+    void
+    InitializeChunkedIterators(
+        const dataset::SearchDataset& dataset,
+        const SearchInfo& search_info,
+        const std::map<std::string, std::string>& index_info,
+        const BitsetView& bitset,
+        const milvus::DataType& data_type,
+        const GetChunkDataFunc& get_chunk_data);
+};
+}  // namespace milvus::query

internal/core/src/query/PlanProto.cpp

@@ -93,6 +93,20 @@ ProtoParser::PlanNodeFromProto(const planpb::PlanNode& plan_node_proto) {
             search_info.strict_group_size_ =
                 query_info_proto.strict_group_size();
         }
+
+        if (query_info_proto.has_search_iterator_v2_info()) {
+            auto& iterator_v2_info_proto =
+                query_info_proto.search_iterator_v2_info();
+            search_info.iterator_v2_info_ = SearchIteratorV2Info{
+                .token = iterator_v2_info_proto.token(),
+                .batch_size = iterator_v2_info_proto.batch_size(),
+            };
+            if (iterator_v2_info_proto.has_last_bound()) {
+                search_info.iterator_v2_info_->last_bound =
+                    iterator_v2_info_proto.last_bound();
+            }
+        }
+
         return search_info;
     };
 

internal/core/src/query/SearchBruteForce.cpp

@@ -226,45 +226,66 @@ BruteForceSearch(const dataset::SearchDataset& query_ds,
     return sub_result;
 }
 
-SubSearchResult
+knowhere::expected<std::vector<knowhere::IndexNode::IteratorPtr>>
-BruteForceSearchIterators(const dataset::SearchDataset& query_ds,
+DispatchBruteForceIteratorByDataType(const knowhere::DataSetPtr& base_dataset,
-                          const dataset::RawDataset& raw_ds,
+                                     const knowhere::DataSetPtr& query_dataset,
-                          const SearchInfo& search_info,
+                                     const knowhere::Json& config,
-                          const std::map<std::string, std::string>& index_info,
+                                     const BitsetView& bitset,
-                          const BitsetView& bitset,
+                                     const milvus::DataType& data_type) {
-                          DataType data_type) {
-    auto nq = query_ds.num_queries;
-    auto [query_dataset, base_dataset] =
-        PrepareBFDataSet(query_ds, raw_ds, data_type);
-    auto search_cfg = PrepareBFSearchParams(search_info, index_info);
-
-    knowhere::expected<std::vector<knowhere::IndexNode::IteratorPtr>>
-        iterators_val;
     switch (data_type) {
         case DataType::VECTOR_FLOAT:
-            iterators_val = knowhere::BruteForce::AnnIterator<float>(
+            return knowhere::BruteForce::AnnIterator<float>(
-                base_dataset, query_dataset, search_cfg, bitset);
+                base_dataset, query_dataset, config, bitset);
             break;
         case DataType::VECTOR_FLOAT16:
             //todo: if knowhere support real fp16/bf16 bf, change it
-            iterators_val = knowhere::BruteForce::AnnIterator<float>(
+            return knowhere::BruteForce::AnnIterator<float>(
-                base_dataset, query_dataset, search_cfg, bitset);
+                base_dataset, query_dataset, config, bitset);
             break;
         case DataType::VECTOR_BFLOAT16:
             //todo: if knowhere support real fp16/bf16 bf, change it
-            iterators_val = knowhere::BruteForce::AnnIterator<float>(
+            return knowhere::BruteForce::AnnIterator<float>(
-                base_dataset, query_dataset, search_cfg, bitset);
+                base_dataset, query_dataset, config, bitset);
             break;
         case DataType::VECTOR_SPARSE_FLOAT:
-            iterators_val = knowhere::BruteForce::AnnIterator<
+            return knowhere::BruteForce::AnnIterator<
                 knowhere::sparse::SparseRow<float>>(
-                base_dataset, query_dataset, search_cfg, bitset);
+                base_dataset, query_dataset, config, bitset);
             break;
         default:
             PanicInfo(ErrorCode::Unsupported,
                       "Unsupported dataType for chunk brute force iterator:{}",
                       data_type);
     }
+}
+
+knowhere::expected<std::vector<knowhere::IndexNode::IteratorPtr>>
+GetBruteForceSearchIterators(
+    const dataset::SearchDataset& query_ds,
+    const dataset::RawDataset& raw_ds,
+    const SearchInfo& search_info,
+    const std::map<std::string, std::string>& index_info,
+    const BitsetView& bitset,
+    DataType data_type) {
+    auto nq = query_ds.num_queries;
+    auto [query_dataset, base_dataset] =
+        PrepareBFDataSet(query_ds, raw_ds, data_type);
+    auto search_cfg = PrepareBFSearchParams(search_info, index_info);
+    return DispatchBruteForceIteratorByDataType(
+        base_dataset, query_dataset, search_cfg, bitset, data_type);
+}
+
+SubSearchResult
+PackBruteForceSearchIteratorsIntoSubResult(
+    const dataset::SearchDataset& query_ds,
+    const dataset::RawDataset& raw_ds,
+    const SearchInfo& search_info,
+    const std::map<std::string, std::string>& index_info,
+    const BitsetView& bitset,
+    DataType data_type) {
+    auto nq = query_ds.num_queries;
+    auto iterators_val = GetBruteForceSearchIterators(
+        query_ds, raw_ds, search_info, index_info, bitset, data_type);
     if (iterators_val.has_value()) {
         AssertInfo(
             iterators_val.value().size() == nq,

internal/core/src/query/SearchBruteForce.h

@@ -31,12 +31,22 @@ BruteForceSearch(const dataset::SearchDataset& query_ds,
                  const BitsetView& bitset,
                  DataType data_type);
 
+knowhere::expected<std::vector<knowhere::IndexNode::IteratorPtr>>
+GetBruteForceSearchIterators(
+    const dataset::SearchDataset& query_ds,
+    const dataset::RawDataset& raw_ds,
+    const SearchInfo& search_info,
+    const std::map<std::string, std::string>& index_info,
+    const BitsetView& bitset,
+    DataType data_type);
+
 SubSearchResult
-BruteForceSearchIterators(const dataset::SearchDataset& query_ds,
+PackBruteForceSearchIteratorsIntoSubResult(
-                          const dataset::RawDataset& raw_ds,
+    const dataset::SearchDataset& query_ds,
-                          const SearchInfo& search_info,
+    const dataset::RawDataset& raw_ds,
-                          const std::map<std::string, std::string>& index_info,
+    const SearchInfo& search_info,
-                          const BitsetView& bitset,
+    const std::map<std::string, std::string>& index_info,
-                          DataType data_type);
+    const BitsetView& bitset,
+    DataType data_type);
 
 }  // namespace milvus::query

internal/core/src/query/SearchOnGrowing.cpp

@@ -18,6 +18,7 @@
 #include "knowhere/comp/index_param.h"
 #include "knowhere/config.h"
 #include "log/Log.h"
+#include "query/CachedSearchIterator.h"
 #include "query/SearchBruteForce.h"
 #include "query/SearchOnIndex.h"
 #include "exec/operator/Utils.h"
@@ -125,6 +126,19 @@ SearchOnGrowing(const segcore::SegmentGrowingImpl& segment,
 
         // step 3: brute force search where small indexing is unavailable
         auto vec_ptr = record.get_data_base(vecfield_id);
+
+        if (info.iterator_v2_info_.has_value()) {
+            CachedSearchIterator cached_iter(search_dataset,
+                                             vec_ptr,
+                                             active_count,
+                                             info,
+                                             index_info,
+                                             bitset,
+                                             data_type);
+            cached_iter.NextBatch(info, search_result);
+            return;
+        }
+
         auto vec_size_per_chunk = vec_ptr->get_size_per_chunk();
         auto max_chunk = upper_div(active_count, vec_size_per_chunk);
 
@@ -140,12 +154,13 @@ SearchOnGrowing(const segcore::SegmentGrowingImpl& segment,
             auto sub_data = query::dataset::RawDataset{
                 element_begin, dim, size_per_chunk, chunk_data};
             if (milvus::exec::UseVectorIterator(info)) {
-                auto sub_qr = BruteForceSearchIterators(search_dataset,
+                auto sub_qr =
-                                                        sub_data,
+                    PackBruteForceSearchIteratorsIntoSubResult(search_dataset,
-                                                        info,
+                                                               sub_data,
-                                                        index_info,
+                                                               info,
-                                                        bitset,
+                                                               index_info,
-                                                        data_type);
+                                                               bitset,
+                                                               data_type);
                 final_qr.merge(sub_qr);
             } else {
                 auto sub_qr = BruteForceSearch(search_dataset,

internal/core/src/query/SearchOnIndex.cpp

@@ -11,6 +11,7 @@
 
 #include "SearchOnIndex.h"
 #include "exec/operator/Utils.h"
+#include "CachedSearchIterator.h"
 
 namespace milvus::query {
 void
@@ -26,14 +27,23 @@ SearchOnIndex(const dataset::SearchDataset& search_dataset,
     auto dataset =
         knowhere::GenDataSet(num_queries, dim, search_dataset.query_data);
     dataset->SetIsSparse(is_sparse);
-    if (!milvus::exec::PrepareVectorIteratorsFromIndex(search_conf,
+    if (milvus::exec::PrepareVectorIteratorsFromIndex(search_conf,
-                                                       num_queries,
+                                                      num_queries,
-                                                       dataset,
+                                                      dataset,
-                                                       search_result,
+                                                      search_result,
-                                                       bitset,
+                                                      bitset,
-                                                       indexing)) {
+                                                      indexing)) {
-        indexing.Query(dataset, search_conf, bitset, search_result);
+        return;
     }
+
+    if (search_conf.iterator_v2_info_.has_value()) {
+        auto iter =
+            CachedSearchIterator(indexing, dataset, search_conf, bitset);
+        iter.NextBatch(search_conf, search_result);
+        return;
+    }
+
+    indexing.Query(dataset, search_conf, bitset, search_result);
 }
 
 }  // namespace milvus::query

internal/core/src/query/SearchOnSealed.cpp

@@ -18,6 +18,7 @@
 #include "common/QueryInfo.h"
 #include "common/Types.h"
 #include "mmap/Column.h"
+#include "query/CachedSearchIterator.h"
 #include "query/SearchBruteForce.h"
 #include "query/SearchOnSealed.h"
 #include "query/helper.h"
@@ -55,13 +56,20 @@ SearchOnSealedIndex(const Schema& schema,
     dataset->SetIsSparse(is_sparse);
     auto vec_index =
         dynamic_cast<index::VectorIndex*>(field_indexing->indexing_.get());
+
+    if (search_info.iterator_v2_info_.has_value()) {
+        CachedSearchIterator cached_iter(
+            *vec_index, dataset, search_info, bitset);
+        cached_iter.NextBatch(search_info, search_result);
+        return;
+    }
+
     if (!milvus::exec::PrepareVectorIteratorsFromIndex(search_info,
                                                        num_queries,
                                                        dataset,
                                                        search_result,
                                                        bitset,
                                                        *vec_index)) {
-        auto index_type = vec_index->GetIndexType();
         vec_index->Query(dataset, search_info, bitset, search_result);
         float* distances = search_result.distances_.data();
         auto total_num = num_queries * topK;
@@ -104,6 +112,14 @@ SearchOnSealed(const Schema& schema,
 
     auto data_type = field.get_data_type();
     CheckBruteForceSearchParam(field, search_info);
+
+    if (search_info.iterator_v2_info_.has_value()) {
+        CachedSearchIterator cached_iter(
+            column, query_dataset, search_info, index_info, bitview, data_type);
+        cached_iter.NextBatch(search_info, result);
+        return;
+    }
+
     auto num_chunk = column->num_chunks();
 
     SubSearchResult final_qr(num_queries,
@@ -115,17 +131,16 @@ SearchOnSealed(const Schema& schema,
     for (int i = 0; i < num_chunk; ++i) {
         auto vec_data = column->Data(i);
         auto chunk_size = column->chunk_row_nums(i);
-        const uint8_t* bitset_ptr = nullptr;
-        auto data_id = offset;
         auto raw_dataset =
             query::dataset::RawDataset{offset, dim, chunk_size, vec_data};
         if (milvus::exec::UseVectorIterator(search_info)) {
-            auto sub_qr = BruteForceSearchIterators(query_dataset,
+            auto sub_qr =
-                                                    raw_dataset,
+                PackBruteForceSearchIteratorsIntoSubResult(query_dataset,
-                                                    search_info,
+                                                           raw_dataset,
-                                                    index_info,
+                                                           search_info,
-                                                    bitview,
+                                                           index_info,
-                                                    data_type);
+                                                           bitview,
+                                                           data_type);
             final_qr.merge(sub_qr);
         } else {
             auto sub_qr = BruteForceSearch(query_dataset,
@@ -136,7 +151,6 @@ SearchOnSealed(const Schema& schema,
                                            data_type);
             final_qr.merge(sub_qr);
         }
-
         offset += chunk_size;
     }
     if (milvus::exec::UseVectorIterator(search_info)) {
@@ -181,14 +195,23 @@ SearchOnSealed(const Schema& schema,
     CheckBruteForceSearchParam(field, search_info);
     auto raw_dataset = query::dataset::RawDataset{0, dim, row_count, vec_data};
     if (milvus::exec::UseVectorIterator(search_info)) {
-        auto sub_qr = BruteForceSearchIterators(query_dataset,
+        auto sub_qr = PackBruteForceSearchIteratorsIntoSubResult(query_dataset,
-                                                raw_dataset,
+                                                                 raw_dataset,
-                                                search_info,
+                                                                 search_info,
-                                                index_info,
+                                                                 index_info,
-                                                bitset,
+                                                                 bitset,
-                                                data_type);
+                                                                 data_type);
         result.AssembleChunkVectorIterators(
             num_queries, 1, {0}, sub_qr.chunk_iterators());
+    } else if (search_info.iterator_v2_info_.has_value()) {
+        CachedSearchIterator cached_iter(query_dataset,
+                                         raw_dataset,
+                                         search_info,
+                                         index_info,
+                                         bitset,
+                                         data_type);
+        cached_iter.NextBatch(search_info, result);
+        return;
     } else {
         auto sub_qr = BruteForceSearch(query_dataset,
                                        raw_dataset,

internal/core/unittest/CMakeLists.txt

@@ -89,6 +89,7 @@ set(MILVUS_TEST_FILES
         test_chunked_segment.cpp
         test_chunked_column.cpp
         test_rust_result.cpp
+        test_cached_search_iterator.cpp
         )
 
 if ( INDEX_ENGINE STREQUAL "cardinal" )

internal/core/unittest/test_bf_sparse.cpp

@@ -143,12 +143,13 @@ class TestSparseFloatSearchBruteForce : public ::testing::Test {
             AssertMatch(ref, ans);
         }
 
-        auto result3 = BruteForceSearchIterators(query_dataset,
+        auto result3 = PackBruteForceSearchIteratorsIntoSubResult(
-                                                 raw_dataset,
+            query_dataset,
-                                                 search_info,
+            raw_dataset,
-                                                 index_info,
+            search_info,
-                                                 bitset_view,
+            index_info,
-                                                 DataType::VECTOR_SPARSE_FLOAT);
+            bitset_view,
+            DataType::VECTOR_SPARSE_FLOAT);
         auto iterators = result3.chunk_iterators();
         for (int i = 0; i < nq; i++) {
             auto it = iterators[i];

internal/core/unittest/test_cached_search_iterator.cpp

@@ -0,0 +1,797 @@
+// Copyright (C) 2019-2020 Zilliz. All rights reserved.
+//
+// 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 <gtest/gtest.h>
+#include <memory>
+#include <random>
+#include <unordered_set>
+#include "common/BitsetView.h"
+#include "common/QueryInfo.h"
+#include "common/QueryResult.h"
+#include "common/Utils.h"
+#include "index/Index.h"
+#include "knowhere/comp/index_param.h"
+#include "query/CachedSearchIterator.h"
+#include "index/VectorIndex.h"
+#include "index/IndexFactory.h"
+#include "knowhere/dataset.h"
+#include "query/helper.h"
+#include "segcore/ConcurrentVector.h"
+#include "segcore/InsertRecord.h"
+#include "mmap/ChunkedColumn.h"
+#include "test_utils/DataGen.h"
+
+using namespace milvus;
+using namespace milvus::query;
+using namespace milvus::segcore;
+using namespace milvus::index;
+
+namespace {
+constexpr int64_t kDim = 16;
+constexpr int64_t kNumVectors = 1000;
+constexpr int64_t kNumQueries = 1;
+constexpr int64_t kBatchSize = 100;
+constexpr size_t kSizePerChunk = 128;
+constexpr size_t kHnswM = 24;
+constexpr size_t kHnswEfConstruction = 360;
+constexpr size_t kHnswEf = 128;
+
+const MetricType kMetricType = knowhere::metric::L2;
+}  // namespace
+
+enum class ConstructorType {
+    VectorIndex = 0,
+    RawData,
+    VectorBase,
+    ChunkedColumn
+};
+
+static const std::vector<ConstructorType> kConstructorTypes = {
+    ConstructorType::VectorIndex,
+    ConstructorType::RawData,
+    ConstructorType::VectorBase,
+    ConstructorType::ChunkedColumn,
+};
+
+static const std::vector<MetricType> kMetricTypes = {
+    knowhere::metric::L2,
+    knowhere::metric::IP,
+    knowhere::metric::COSINE,
+};
+
+// this class does not support test concurrently
+class CachedSearchIteratorTest
+    : public ::testing::TestWithParam<std::tuple<ConstructorType, MetricType>> {
+ private:
+ protected:
+    SearchInfo
+    GetDefaultNormalSearchInfo() {
+        return SearchInfo{
+            .topk_ = kBatchSize,
+            .round_decimal_ = -1,
+            .metric_type_ = std::get<1>(GetParam()),
+            .search_params_ =
+                {
+                    {knowhere::indexparam::EF, std::to_string(kHnswEf)},
+                },
+            .iterator_v2_info_ =
+                SearchIteratorV2Info{
+                    .batch_size = kBatchSize,
+                },
+        };
+    }
+
+    static DataType data_type_;
+    static int64_t dim_;
+    static int64_t nb_;
+    static int64_t nq_;
+    static FixedVector<float> base_dataset_;
+    static FixedVector<float> query_dataset_;
+    static IndexBasePtr index_hnsw_l2_;
+    static IndexBasePtr index_hnsw_ip_;
+    static IndexBasePtr index_hnsw_cos_;
+    static knowhere::DataSetPtr knowhere_query_dataset_;
+    static dataset::SearchDataset search_dataset_;
+    static std::unique_ptr<ConcurrentVector<milvus::FloatVector>> vector_base_;
+    static std::shared_ptr<ChunkedColumn> column_;
+    static std::vector<std::vector<char>> column_data_;
+
+    IndexBase* index_hnsw_ = nullptr;
+    MetricType metric_type_ = kMetricType;
+
+    std::unique_ptr<CachedSearchIterator>
+    DispatchIterator(const ConstructorType& constructor_type,
+                     const SearchInfo& search_info,
+                     const BitsetView& bitset) {
+        switch (constructor_type) {
+            case ConstructorType::VectorIndex:
+                return std::make_unique<CachedSearchIterator>(
+                    dynamic_cast<const VectorIndex&>(*index_hnsw_),
+                    knowhere_query_dataset_,
+                    search_info,
+                    bitset);
+
+            case ConstructorType::RawData:
+                return std::make_unique<CachedSearchIterator>(
+                    search_dataset_,
+                    dataset::RawDataset{0, dim_, nb_, base_dataset_.data()},
+                    search_info,
+                    std::map<std::string, std::string>{},
+                    bitset,
+                    data_type_);
+
+            case ConstructorType::VectorBase:
+                return std::make_unique<CachedSearchIterator>(
+                    search_dataset_,
+                    vector_base_.get(),
+                    nb_,
+                    search_info,
+                    std::map<std::string, std::string>{},
+                    bitset,
+                    data_type_);
+
+            case ConstructorType::ChunkedColumn:
+                return std::make_unique<CachedSearchIterator>(
+                    column_,
+                    search_dataset_,
+                    search_info,
+                    std::map<std::string, std::string>{},
+                    bitset,
+                    data_type_);
+            default:
+                return nullptr;
+        }
+    }
+
+    // use last distance of the first batch as range_filter
+    // use first distance of the last batch as radius
+    std::pair<float, float>
+    GetRadiusAndRangeFilter() {
+        const size_t num_rnds = (nb_ + kBatchSize - 1) / kBatchSize;
+        SearchResult search_result;
+        float radius, range_filter;
+        bool get_radius_success = false;
+        bool get_range_filter_sucess = false;
+        SearchInfo search_info = GetDefaultNormalSearchInfo();
+        auto iterator =
+            DispatchIterator(std::get<0>(GetParam()), search_info, nullptr);
+        for (size_t rnd = 0; rnd < num_rnds; ++rnd) {
+            iterator->NextBatch(search_info, search_result);
+            if (rnd == 0) {
+                for (size_t i = kBatchSize - 1; i >= 0; --i) {
+                    if (search_result.seg_offsets_[i] != -1) {
+                        range_filter = search_result.distances_[i];
+                        get_range_filter_sucess = true;
+                        break;
+                    }
+                }
+            } else {
+                for (size_t i = 0; i < kBatchSize; ++i) {
+                    if (search_result.seg_offsets_[i] != -1) {
+                        radius = search_result.distances_[i];
+                        get_radius_success = true;
+                        break;
+                    }
+                }
+            }
+        }
+        if (!get_radius_success || !get_range_filter_sucess) {
+            throw std::runtime_error("Failed to get radius and range filter");
+        }
+        return {radius, range_filter};
+    }
+
+    static void
+    BuildIndex() {
+        auto dataset = knowhere::GenDataSet(nb_, dim_, base_dataset_.data());
+
+        for (const auto& metric_type : kMetricTypes) {
+            milvus::index::CreateIndexInfo create_index_info;
+            create_index_info.field_type = data_type_;
+            create_index_info.metric_type = metric_type;
+            create_index_info.index_engine_version =
+                knowhere::Version::GetCurrentVersion().VersionNumber();
+            auto build_conf = knowhere::Json{
+                {knowhere::meta::METRIC_TYPE, knowhere::metric::L2},
+                {knowhere::meta::DIM, std::to_string(dim_)},
+                {knowhere::indexparam::M, std::to_string(kHnswM)},
+                {knowhere::indexparam::EFCONSTRUCTION,
+                 std::to_string(kHnswEfConstruction)}};
+            create_index_info.index_type = knowhere::IndexEnum::INDEX_HNSW;
+            if (metric_type == knowhere::metric::L2) {
+                index_hnsw_l2_ =
+                    milvus::index::IndexFactory::GetInstance().CreateIndex(
+                        create_index_info,
+                        milvus::storage::FileManagerContext());
+                index_hnsw_l2_->BuildWithDataset(dataset, build_conf);
+                ASSERT_EQ(index_hnsw_l2_->Count(), nb_);
+            } else if (metric_type == knowhere::metric::IP) {
+                index_hnsw_ip_ =
+                    milvus::index::IndexFactory::GetInstance().CreateIndex(
+                        create_index_info,
+                        milvus::storage::FileManagerContext());
+                index_hnsw_ip_->BuildWithDataset(dataset, build_conf);
+                ASSERT_EQ(index_hnsw_ip_->Count(), nb_);
+            } else if (metric_type == knowhere::metric::COSINE) {
+                index_hnsw_cos_ =
+                    milvus::index::IndexFactory::GetInstance().CreateIndex(
+                        create_index_info,
+                        milvus::storage::FileManagerContext());
+                index_hnsw_cos_->BuildWithDataset(dataset, build_conf);
+                ASSERT_EQ(index_hnsw_cos_->Count(), nb_);
+            } else {
+                FAIL() << "Unsupported metric type: " << metric_type;
+            }
+        }
+    }
+
+    static void
+    SetUpVectorBase() {
+        vector_base_ = std::make_unique<ConcurrentVector<milvus::FloatVector>>(
+            dim_, kSizePerChunk);
+        vector_base_->set_data_raw(0, base_dataset_.data(), nb_);
+
+        ASSERT_EQ(vector_base_->num_chunk(),
+                  (nb_ + kSizePerChunk - 1) / kSizePerChunk);
+    }
+
+    static void
+    SetUpChunkedColumn() {
+        column_ = std::make_unique<ChunkedColumn>();
+        const size_t num_chunks_ = (nb_ + kSizePerChunk - 1) / kSizePerChunk;
+        column_data_.resize(num_chunks_);
+
+        size_t offset = 0;
+        for (size_t i = 0; i < num_chunks_; ++i) {
+            const size_t rows = std::min(nb_ - offset, kSizePerChunk);
+            const size_t chunk_bitset_size = (rows + 7) / 8;
+            const size_t buf_size =
+                chunk_bitset_size + rows * dim_ * sizeof(float);
+            auto& chunk_data = column_data_[i];
+            chunk_data.resize(buf_size);
+            memcpy(chunk_data.data() + chunk_bitset_size,
+                   base_dataset_.cbegin() + offset * dim_,
+                   rows * dim_ * sizeof(float));
+            column_->AddChunk(std::make_shared<FixedWidthChunk>(
+                rows, dim_, chunk_data.data(), buf_size, sizeof(float), false));
+            offset += rows;
+        }
+    }
+
+    static void
+    SetUpTestSuite() {
+        auto schema = std::make_shared<Schema>();
+        auto fakevec_id = schema->AddDebugField(
+            "fakevec", DataType::VECTOR_FLOAT, dim_, kMetricType);
+
+        // generate base dataset
+        base_dataset_ =
+            segcore::DataGen(schema, nb_).get_col<float>(fakevec_id);
+
+        // generate query dataset
+        query_dataset_ = {base_dataset_.cbegin(),
+                          base_dataset_.cbegin() + nq_ * dim_};
+        knowhere_query_dataset_ =
+            knowhere::GenDataSet(nq_, dim_, query_dataset_.data());
+        search_dataset_ = dataset::SearchDataset{
+            .metric_type = kMetricType,
+            .num_queries = nq_,
+            .topk = kBatchSize,
+            .round_decimal = -1,
+            .dim = dim_,
+            .query_data = query_dataset_.data(),
+        };
+
+        BuildIndex();
+        SetUpVectorBase();
+        SetUpChunkedColumn();
+    }
+
+    static void
+    TearDownTestSuite() {
+        base_dataset_.clear();
+        query_dataset_.clear();
+        index_hnsw_l2_.reset();
+        index_hnsw_ip_.reset();
+        index_hnsw_cos_.reset();
+        knowhere_query_dataset_.reset();
+        vector_base_.reset();
+        column_.reset();
+    }
+
+    void
+    SetUp() override {
+        auto metric_type = std::get<1>(GetParam());
+        if (metric_type == knowhere::metric::L2) {
+            metric_type_ = knowhere::metric::L2;
+            search_dataset_.metric_type = knowhere::metric::L2;
+            index_hnsw_ = index_hnsw_l2_.get();
+        } else if (metric_type == knowhere::metric::IP) {
+            metric_type_ = knowhere::metric::IP;
+            search_dataset_.metric_type = knowhere::metric::IP;
+            index_hnsw_ = index_hnsw_ip_.get();
+        } else if (metric_type == knowhere::metric::COSINE) {
+            metric_type_ = knowhere::metric::COSINE;
+            search_dataset_.metric_type = knowhere::metric::COSINE;
+            index_hnsw_ = index_hnsw_cos_.get();
+        } else {
+            FAIL() << "Unsupported metric type: " << metric_type;
+        }
+    }
+
+    void
+    TearDown() override {
+    }
+};
+
+// initialize static variables
+DataType CachedSearchIteratorTest::data_type_ = DataType::VECTOR_FLOAT;
+int64_t CachedSearchIteratorTest::dim_ = kDim;
+int64_t CachedSearchIteratorTest::nb_ = kNumVectors;
+int64_t CachedSearchIteratorTest::nq_ = kNumQueries;
+IndexBasePtr CachedSearchIteratorTest::index_hnsw_l2_ = nullptr;
+IndexBasePtr CachedSearchIteratorTest::index_hnsw_ip_ = nullptr;
+IndexBasePtr CachedSearchIteratorTest::index_hnsw_cos_ = nullptr;
+knowhere::DataSetPtr CachedSearchIteratorTest::knowhere_query_dataset_ =
+    nullptr;
+dataset::SearchDataset CachedSearchIteratorTest::search_dataset_;
+FixedVector<float> CachedSearchIteratorTest::base_dataset_;
+FixedVector<float> CachedSearchIteratorTest::query_dataset_;
+std::unique_ptr<ConcurrentVector<milvus::FloatVector>>
+    CachedSearchIteratorTest::vector_base_ = nullptr;
+std::shared_ptr<ChunkedColumn> CachedSearchIteratorTest::column_ = nullptr;
+std::vector<std::vector<char>> CachedSearchIteratorTest::column_data_;
+
+/********* Testcases Start **********/
+
+TEST_P(CachedSearchIteratorTest, NextBatchNormal) {
+    SearchInfo search_info = GetDefaultNormalSearchInfo();
+    const std::vector<size_t> kBatchSizes = {
+        1, 7, 43, 99, 100, 101, 1000, 1005};
+
+    for (size_t batch_size : kBatchSizes) {
+        std::cout << "batch_size: " << batch_size << std::endl;
+        search_info.iterator_v2_info_->batch_size = batch_size;
+        auto iterator =
+            DispatchIterator(std::get<0>(GetParam()), search_info, nullptr);
+        SearchResult search_result;
+
+        iterator->NextBatch(search_info, search_result);
+
+        for (size_t i = 0; i < nq_; ++i) {
+            std::unordered_set<int64_t> seg_offsets;
+            size_t cnt = 0;
+            for (size_t j = 0; j < batch_size; ++j) {
+                if (search_result.seg_offsets_[i * batch_size + j] == -1) {
+                    break;
+                }
+                ++cnt;
+                seg_offsets.insert(
+                    search_result.seg_offsets_[i * batch_size + j]);
+            }
+            EXPECT_EQ(seg_offsets.size(), cnt);
+            if (metric_type_ == knowhere::metric::L2) {
+                EXPECT_EQ(search_result.distances_[i * batch_size], 0);
+            }
+        }
+        EXPECT_EQ(search_result.unity_topK_, batch_size);
+        EXPECT_EQ(search_result.total_nq_, nq_);
+        EXPECT_EQ(search_result.seg_offsets_.size(), nq_ * batch_size);
+        EXPECT_EQ(search_result.distances_.size(), nq_ * batch_size);
+    }
+}
+
+TEST_P(CachedSearchIteratorTest, NextBatchDistBound) {
+    SearchInfo search_info = GetDefaultNormalSearchInfo();
+    const size_t batch_size = kBatchSize;
+    const float dist_bound_factor = PositivelyRelated(metric_type_) ? 0.5 : 1.5;
+    float dist_bound = 0;
+
+    {
+        auto iterator =
+            DispatchIterator(std::get<0>(GetParam()), search_info, nullptr);
+        SearchResult search_result;
+        iterator->NextBatch(search_info, search_result);
+
+        bool found_dist_bound = false;
+        // use the last distance of the first query * factor as the dist bound
+        for (size_t j = batch_size - 1; j >= 0; --j) {
+            if (search_result.seg_offsets_[j] != -1) {
+                dist_bound = search_result.distances_[j] * dist_bound_factor;
+                found_dist_bound = true;
+                break;
+            }
+        }
+        ASSERT_TRUE(found_dist_bound);
+
+        search_info.iterator_v2_info_->last_bound = dist_bound;
+        for (size_t rnd = 1; rnd < (nb_ + batch_size - 1) / batch_size; ++rnd) {
+            iterator->NextBatch(search_info, search_result);
+            for (size_t i = 0; i < nq_; ++i) {
+                for (size_t j = 0; j < batch_size; ++j) {
+                    if (search_result.seg_offsets_[i * batch_size + j] == -1) {
+                        break;
+                    }
+                    if (PositivelyRelated(metric_type_)) {
+                        EXPECT_LT(search_result.distances_[i * batch_size + j],
+                                  dist_bound);
+                    } else {
+                        EXPECT_GT(search_result.distances_[i * batch_size + j],
+                                  dist_bound);
+                    }
+                }
+            }
+        }
+    }
+}
+
+TEST_P(CachedSearchIteratorTest, NextBatchDistBoundEmptyResults) {
+    SearchInfo search_info = GetDefaultNormalSearchInfo();
+    const size_t batch_size = kBatchSize;
+    const float dist_bound = PositivelyRelated(metric_type_)
+                                 ? -std::numeric_limits<float>::max()
+                                 : std::numeric_limits<float>::max();
+
+    auto iterator =
+        DispatchIterator(std::get<0>(GetParam()), search_info, nullptr);
+    SearchResult search_result;
+
+    search_info.iterator_v2_info_->last_bound = dist_bound;
+    size_t total_cnt = 0;
+    for (size_t rnd = 0; rnd < (nb_ + batch_size - 1) / batch_size; ++rnd) {
+        iterator->NextBatch(search_info, search_result);
+        for (size_t i = 0; i < nq_; ++i) {
+            for (size_t j = 0; j < batch_size; ++j) {
+                if (search_result.seg_offsets_[i * batch_size + j] == -1) {
+                    break;
+                }
+                ++total_cnt;
+            }
+        }
+    }
+    EXPECT_EQ(total_cnt, 0);
+}
+
+TEST_P(CachedSearchIteratorTest, NextBatchRangeSearchRadius) {
+    const size_t num_rnds = (nb_ + kBatchSize - 1) / kBatchSize;
+    const auto [radius, range_filter] = GetRadiusAndRangeFilter();
+    SearchResult search_result;
+
+    SearchInfo search_info = GetDefaultNormalSearchInfo();
+    search_info.search_params_[knowhere::meta::RADIUS] = radius;
+
+    auto iterator =
+        DispatchIterator(std::get<0>(GetParam()), search_info, nullptr);
+    for (size_t rnd = 0; rnd < num_rnds; ++rnd) {
+        iterator->NextBatch(search_info, search_result);
+        for (size_t i = 0; i < nq_; ++i) {
+            for (size_t j = 0; j < kBatchSize; ++j) {
+                if (search_result.seg_offsets_[i * kBatchSize + j] == -1) {
+                    break;
+                }
+                float dist = search_result.distances_[i * kBatchSize + j];
+                if (PositivelyRelated(metric_type_)) {
+                    ASSERT_GT(dist, radius);
+                } else {
+                    ASSERT_LT(dist, radius);
+                }
+            }
+        }
+    }
+}
+
+TEST_P(CachedSearchIteratorTest, NextBatchRangeSearchRadiusAndRangeFilter) {
+    const size_t num_rnds = (nb_ + kBatchSize - 1) / kBatchSize;
+    const auto [radius, range_filter] = GetRadiusAndRangeFilter();
+    SearchResult search_result;
+
+    SearchInfo search_info = GetDefaultNormalSearchInfo();
+    search_info.search_params_[knowhere::meta::RADIUS] = radius;
+    search_info.search_params_[knowhere::meta::RANGE_FILTER] = range_filter;
+
+    auto iterator =
+        DispatchIterator(std::get<0>(GetParam()), search_info, nullptr);
+    for (size_t rnd = 0; rnd < num_rnds; ++rnd) {
+        iterator->NextBatch(search_info, search_result);
+        for (size_t i = 0; i < nq_; ++i) {
+            for (size_t j = 0; j < kBatchSize; ++j) {
+                if (search_result.seg_offsets_[i * kBatchSize + j] == -1) {
+                    break;
+                }
+                float dist = search_result.distances_[i * kBatchSize + j];
+                if (PositivelyRelated(metric_type_)) {
+                    ASSERT_GT(dist, radius);
+                    ASSERT_LE(dist, range_filter);
+                } else {
+                    ASSERT_LT(dist, radius);
+                    ASSERT_GE(dist, range_filter);
+                }
+            }
+        }
+    }
+}
+
+TEST_P(CachedSearchIteratorTest,
+       NextBatchRangeSearchLastBoundRadiusRangeFilter) {
+    const size_t num_rnds = (nb_ + kBatchSize - 1) / kBatchSize;
+    const auto [radius, range_filter] = GetRadiusAndRangeFilter();
+    SearchResult search_result;
+    const float diff = (radius + range_filter) / 2;
+    const std::vector<float> last_bounds = {radius - diff,
+                                            radius,
+                                            radius + diff,
+                                            range_filter,
+                                            range_filter + diff};
+
+    SearchInfo search_info = GetDefaultNormalSearchInfo();
+    search_info.search_params_[knowhere::meta::RADIUS] = radius;
+    search_info.search_params_[knowhere::meta::RANGE_FILTER] = range_filter;
+    for (float last_bound : last_bounds) {
+        search_info.iterator_v2_info_->last_bound = last_bound;
+        auto iterator =
+            DispatchIterator(std::get<0>(GetParam()), search_info, nullptr);
+        for (size_t rnd = 0; rnd < num_rnds; ++rnd) {
+            iterator->NextBatch(search_info, search_result);
+            for (size_t i = 0; i < nq_; ++i) {
+                for (size_t j = 0; j < kBatchSize; ++j) {
+                    if (search_result.seg_offsets_[i * kBatchSize + j] == -1) {
+                        break;
+                    }
+                    float dist = search_result.distances_[i * kBatchSize + j];
+                    if (PositivelyRelated(metric_type_)) {
+                        ASSERT_LE(dist, last_bound);
+                        ASSERT_GT(dist, radius);
+                        ASSERT_LE(dist, range_filter);
+                    } else {
+                        ASSERT_GT(dist, last_bound);
+                        ASSERT_LT(dist, radius);
+                        ASSERT_GE(dist, range_filter);
+                    }
+                }
+            }
+        }
+    }
+}
+
+TEST_P(CachedSearchIteratorTest, NextBatchZeroBatchSize) {
+    SearchInfo search_info = GetDefaultNormalSearchInfo();
+    auto iterator =
+        DispatchIterator(std::get<0>(GetParam()), search_info, nullptr);
+    SearchResult search_result;
+
+    search_info.iterator_v2_info_->batch_size = 0;
+    EXPECT_THROW(iterator->NextBatch(search_info, search_result), SegcoreError);
+}
+
+TEST_P(CachedSearchIteratorTest, NextBatchDiffBatchSizeComparedToInit) {
+    SearchInfo search_info = GetDefaultNormalSearchInfo();
+    auto iterator =
+        DispatchIterator(std::get<0>(GetParam()), search_info, nullptr);
+    SearchResult search_result;
+
+    search_info.iterator_v2_info_->batch_size = kBatchSize + 1;
+    EXPECT_THROW(iterator->NextBatch(search_info, search_result), SegcoreError);
+}
+
+TEST_P(CachedSearchIteratorTest, NextBatchEmptySearchInfo) {
+    SearchInfo search_info = GetDefaultNormalSearchInfo();
+    auto iterator =
+        DispatchIterator(std::get<0>(GetParam()), search_info, nullptr);
+    SearchResult search_result;
+
+    SearchInfo empty_search_info;
+    EXPECT_THROW(iterator->NextBatch(empty_search_info, search_result),
+                 SegcoreError);
+}
+
+TEST_P(CachedSearchIteratorTest, NextBatchEmptyIteratorV2Info) {
+    SearchInfo search_info = GetDefaultNormalSearchInfo();
+    auto iterator =
+        DispatchIterator(std::get<0>(GetParam()), search_info, nullptr);
+    SearchResult search_result;
+
+    search_info.iterator_v2_info_ = std::nullopt;
+    EXPECT_THROW(iterator->NextBatch(search_info, search_result), SegcoreError);
+}
+
+TEST_P(CachedSearchIteratorTest, NextBatchtAllBatchesNormal) {
+    SearchInfo search_info = GetDefaultNormalSearchInfo();
+    const std::vector<size_t> kBatchSizes = {
+        1, 7, 43, 99, 100, 101, 1000, 1005};
+    // const std::vector<size_t> kBatchSizes = {1005};
+
+    for (size_t batch_size : kBatchSizes) {
+        search_info.iterator_v2_info_->batch_size = batch_size;
+        auto iterator =
+            DispatchIterator(std::get<0>(GetParam()), search_info, nullptr);
+        size_t total_cnt = 0;
+
+        for (size_t rnd = 0; rnd < (nb_ + batch_size - 1) / batch_size; ++rnd) {
+            SearchResult search_result;
+            iterator->NextBatch(search_info, search_result);
+            for (size_t i = 0; i < nq_; ++i) {
+                std::unordered_set<int64_t> seg_offsets;
+                size_t cnt = 0;
+                for (size_t j = 0; j < batch_size; ++j) {
+                    if (search_result.seg_offsets_[i * batch_size + j] == -1) {
+                        break;
+                    }
+                    ++cnt;
+                    seg_offsets.insert(
+                        search_result.seg_offsets_[i * batch_size + j]);
+                }
+                total_cnt += cnt;
+                // check no duplicate
+                EXPECT_EQ(seg_offsets.size(), cnt);
+
+                // only check if the first distance of the first batch is 0
+                if (rnd == 0 && metric_type_ == knowhere::metric::L2) {
+                    EXPECT_EQ(search_result.distances_[i * batch_size], 0);
+                }
+            }
+            EXPECT_EQ(search_result.unity_topK_, batch_size);
+            EXPECT_EQ(search_result.total_nq_, nq_);
+            EXPECT_EQ(search_result.seg_offsets_.size(), nq_ * batch_size);
+            EXPECT_EQ(search_result.distances_.size(), nq_ * batch_size);
+        }
+        if (std::get<0>(GetParam()) == ConstructorType::VectorIndex) {
+            EXPECT_GE(total_cnt, nb_ * nq_ * 0.9);
+        } else {
+            EXPECT_EQ(total_cnt, nb_ * nq_);
+        }
+    }
+}
+
+TEST_P(CachedSearchIteratorTest, ConstructorWithInvalidSearchInfo) {
+    EXPECT_THROW(
+        DispatchIterator(std::get<0>(GetParam()), SearchInfo{}, nullptr),
+        SegcoreError);
+
+    EXPECT_THROW(
+        DispatchIterator(
+            std::get<0>(GetParam()), SearchInfo{.metric_type_ = ""}, nullptr),
+        SegcoreError);
+
+    EXPECT_THROW(DispatchIterator(std::get<0>(GetParam()),
+                                  SearchInfo{.metric_type_ = metric_type_},
+                                  nullptr),
+                 SegcoreError);
+
+    EXPECT_THROW(DispatchIterator(std::get<0>(GetParam()),
+                                  SearchInfo{.metric_type_ = metric_type_,
+                                             .iterator_v2_info_ = {}},
+                                  nullptr),
+                 SegcoreError);
+
+    EXPECT_THROW(
+        DispatchIterator(std::get<0>(GetParam()),
+                         SearchInfo{.metric_type_ = metric_type_,
+                                    .iterator_v2_info_ =
+                                        SearchIteratorV2Info{.batch_size = 0}},
+                         nullptr),
+        SegcoreError);
+}
+
+TEST_P(CachedSearchIteratorTest, ConstructorWithInvalidParams) {
+    SearchInfo search_info = GetDefaultNormalSearchInfo();
+    if (std::get<0>(GetParam()) == ConstructorType::VectorIndex) {
+        EXPECT_THROW(auto iterator = std::make_unique<CachedSearchIterator>(
+                         dynamic_cast<const VectorIndex&>(*index_hnsw_),
+                         nullptr,
+                         search_info,
+                         nullptr),
+                     SegcoreError);
+
+        EXPECT_THROW(auto iterator = std::make_unique<CachedSearchIterator>(
+                         dynamic_cast<const VectorIndex&>(*index_hnsw_),
+                         std::make_shared<knowhere::DataSet>(),
+                         search_info,
+                         nullptr),
+                     SegcoreError);
+    } else if (std::get<0>(GetParam()) == ConstructorType::RawData) {
+        EXPECT_THROW(
+            auto iterator = std::make_unique<CachedSearchIterator>(
+                dataset::SearchDataset{},
+                dataset::RawDataset{0, dim_, nb_, base_dataset_.data()},
+                search_info,
+                std::map<std::string, std::string>{},
+                nullptr,
+                data_type_),
+            SegcoreError);
+    } else if (std::get<0>(GetParam()) == ConstructorType::VectorBase) {
+        EXPECT_THROW(auto iterator = std::make_unique<CachedSearchIterator>(
+                         dataset::SearchDataset{},
+                         vector_base_.get(),
+                         nb_,
+                         search_info,
+                         std::map<std::string, std::string>{},
+                         nullptr,
+                         data_type_),
+                     SegcoreError);
+
+        EXPECT_THROW(auto iterator = std::make_unique<CachedSearchIterator>(
+                         search_dataset_,
+                         nullptr,
+                         nb_,
+                         search_info,
+                         std::map<std::string, std::string>{},
+                         nullptr,
+                         data_type_),
+                     SegcoreError);
+
+        EXPECT_THROW(auto iterator = std::make_unique<CachedSearchIterator>(
+                         search_dataset_,
+                         vector_base_.get(),
+                         0,
+                         search_info,
+                         std::map<std::string, std::string>{},
+                         nullptr,
+                         data_type_),
+                     SegcoreError);
+    } else if (std::get<0>(GetParam()) == ConstructorType::ChunkedColumn) {
+        EXPECT_THROW(auto iterator = std::make_unique<CachedSearchIterator>(
+                         nullptr,
+                         search_dataset_,
+                         search_info,
+                         std::map<std::string, std::string>{},
+                         nullptr,
+                         data_type_),
+                     SegcoreError);
+        EXPECT_THROW(auto iterator = std::make_unique<CachedSearchIterator>(
+                         column_,
+                         dataset::SearchDataset{},
+                         search_info,
+                         std::map<std::string, std::string>{},
+                         nullptr,
+                         data_type_),
+                     SegcoreError);
+    }
+}
+
+/********* Testcases End **********/
+
+INSTANTIATE_TEST_SUITE_P(
+    CachedSearchIteratorTests,
+    CachedSearchIteratorTest,
+    ::testing::Combine(::testing::ValuesIn(kConstructorTypes),
+                       ::testing::ValuesIn(kMetricTypes)),
+    [](const testing::TestParamInfo<std::tuple<ConstructorType, MetricType>>&
+           info) {
+        std::string constructor_type_str;
+        ConstructorType constructor_type = std::get<0>(info.param);
+        MetricType metric_type = std::get<1>(info.param);
+        switch (constructor_type) {
+            case ConstructorType::VectorIndex:
+                constructor_type_str = "VectorIndex";
+                break;
+            case ConstructorType::RawData:
+                constructor_type_str = "RawData";
+                break;
+            case ConstructorType::VectorBase:
+                constructor_type_str = "VectorBase";
+                break;
+            case ConstructorType::ChunkedColumn:
+                constructor_type_str = "ChunkedColumn";
+                break;
+            default:
+                constructor_type_str = "Unknown constructor type";
+        };
+        if (metric_type == knowhere::metric::L2) {
+            constructor_type_str += "_L2";
+        } else if (metric_type == knowhere::metric::IP) {
+            constructor_type_str += "_IP";
+        } else if (metric_type == knowhere::metric::COSINE) {
+            constructor_type_str += "_COSINE";
+        } else {
+            constructor_type_str += "_Unknown";
+        }
+        return constructor_type_str;
+    });

internal/proto/plan.proto

@@ -55,6 +55,12 @@ message Array {
   schema.DataType element_type = 3;
 }
 
+message SearchIteratorV2Info {
+  string token = 1;
+  uint32 batch_size = 2;
+  optional float last_bound = 3;
+}
+
 message QueryInfo {
   int64 topk = 1;
   string metric_type = 3;
@@ -67,6 +73,7 @@ message QueryInfo {
   double bm25_avgdl = 10;
   int64 query_field_id =11;
   string hints = 12;
+  optional SearchIteratorV2Info search_iterator_v2_info = 13;
 }
 
 message ColumnInfo {

internal/proxy/proxy.go

@@ -26,6 +26,7 @@ import (
 	"time"
 
 	"github.com/cockroachdb/errors"
+	"github.com/google/uuid"
 	"github.com/hashicorp/golang-lru/v2/expirable"
 	clientv3 "go.etcd.io/etcd/client/v3"
 	"go.uber.org/atomic"
@@ -304,6 +305,13 @@ func (node *Proxy) Init() error {
 
 	node.enableMaterializedView = Params.CommonCfg.EnableMaterializedView.GetAsBool()
 
+	// Enable internal rand pool for UUIDv4 generation
+	// This is NOT thread-safe and should only be called before the service starts and
+	// there is no possibility that New or any other UUID V4 generation function will be called concurrently
+	// Only proxy generates UUID for now, and one Milvus process only has one proxy
+	uuid.EnableRandPool()
+	log.Debug("enable rand pool for UUIDv4 generation")
+
 	log.Info("init proxy done", zap.Int64("nodeID", paramtable.GetNodeID()), zap.String("Address", node.address))
 	return nil
 }

internal/proxy/search_util.go

@@ -8,6 +8,7 @@ import (
 	"strings"
 
 	"github.com/cockroachdb/errors"
+	"github.com/google/uuid"
 	"google.golang.org/protobuf/proto"
 
 	"github.com/milvus-io/milvus-proto/go-api/v2/commonpb"
@@ -82,6 +83,81 @@ type SearchInfo struct {
 	isIterator bool
 }
 
+func parseSearchIteratorV2Info(searchParamsPair []*commonpb.KeyValuePair, groupByFieldId int64, isIterator bool, offset int64, queryTopK *int64) (*planpb.SearchIteratorV2Info, error) {
+	isIteratorV2Str, _ := funcutil.GetAttrByKeyFromRepeatedKV(SearchIterV2Key, searchParamsPair)
+	isIteratorV2, _ := strconv.ParseBool(isIteratorV2Str)
+	if !isIteratorV2 {
+		return nil, nil
+	}
+
+	// iteratorV1 and iteratorV2 should be set together for compatibility
+	if !isIterator {
+		return nil, fmt.Errorf("both %s and %s must be set in the SDK", IteratorField, SearchIterV2Key)
+	}
+
+	// disable groupBy when doing iteratorV2
+	// same behavior with V1
+	if isIteratorV2 && groupByFieldId > 0 {
+		return nil, merr.WrapErrParameterInvalid("", "",
+			"GroupBy is not permitted when using a search iterator")
+	}
+
+	// disable offset when doing iteratorV2
+	if isIteratorV2 && offset > 0 {
+		return nil, merr.WrapErrParameterInvalid("", "",
+			"Setting an offset is not permitted when using a search iterator v2")
+	}
+
+	// parse token, generate if not exist
+	token, _ := funcutil.GetAttrByKeyFromRepeatedKV(SearchIterIdKey, searchParamsPair)
+	if token == "" {
+		generatedToken, err := uuid.NewRandom()
+		if err != nil {
+			return nil, err
+		}
+		token = generatedToken.String()
+	} else {
+		// Validate existing token is a valid UUID
+		if _, err := uuid.Parse(token); err != nil {
+			return nil, fmt.Errorf("invalid token format")
+		}
+	}
+
+	// parse batch size, required non-zero value
+	batchSizeStr, _ := funcutil.GetAttrByKeyFromRepeatedKV(SearchIterBatchSizeKey, searchParamsPair)
+	if batchSizeStr == "" {
+		return nil, fmt.Errorf("batch size is required")
+	}
+	batchSize, err := strconv.ParseInt(batchSizeStr, 0, 64)
+	if err != nil {
+		return nil, fmt.Errorf("batch size is invalid, %w", err)
+	}
+	// use the same validation logic as topk
+	if err := validateLimit(batchSize); err != nil {
+		return nil, fmt.Errorf("batch size is invalid, %w", err)
+	}
+	*queryTopK = batchSize // for compatibility
+
+	// prepare plan iterator v2 info proto
+	planIteratorV2Info := &planpb.SearchIteratorV2Info{
+		Token:     token,
+		BatchSize: uint32(batchSize),
+	}
+
+	// append optional last bound if applicable
+	lastBoundStr, _ := funcutil.GetAttrByKeyFromRepeatedKV(SearchIterLastBoundKey, searchParamsPair)
+	if lastBoundStr != "" {
+		lastBound, err := strconv.ParseFloat(lastBoundStr, 32)
+		if err != nil {
+			return nil, fmt.Errorf("failed to parse input last bound, %w", err)
+		}
+		lastBoundFloat32 := float32(lastBound)
+		planIteratorV2Info.LastBound = &lastBoundFloat32 // escape pointer
+	}
+
+	return planIteratorV2Info, nil
+}
+
 // parseSearchInfo returns QueryInfo and offset
 func parseSearchInfo(searchParamsPair []*commonpb.KeyValuePair, schema *schemapb.CollectionSchema, rankParams *rankParams) *SearchInfo {
 	var topK int64
@@ -196,16 +272,22 @@ func parseSearchInfo(searchParamsPair []*commonpb.KeyValuePair, schema *schemapb
 			"Not allowed to do range-search when doing search-group-by")}
 	}
 
+	planSearchIteratorV2Info, err := parseSearchIteratorV2Info(searchParamsPair, groupByFieldId, isIterator, offset, &queryTopK)
+	if err != nil {
+		return &SearchInfo{planInfo: nil, offset: 0, isIterator: false, parseError: fmt.Errorf("parse iterator v2 info failed: %w", err)}
+	}
+
 	return &SearchInfo{
 		planInfo: &planpb.QueryInfo{
-			Topk:            queryTopK,
+			Topk:                 queryTopK,
-			MetricType:      metricType,
+			MetricType:           metricType,
-			SearchParams:    searchParamStr,
+			SearchParams:         searchParamStr,
-			RoundDecimal:    roundDecimal,
+			RoundDecimal:         roundDecimal,
-			GroupByFieldId:  groupByFieldId,
+			GroupByFieldId:       groupByFieldId,
-			GroupSize:       groupSize,
+			GroupSize:            groupSize,
-			StrictGroupSize: strictGroupSize,
+			StrictGroupSize:      strictGroupSize,
-			Hints:           hints,
+			Hints:                hints,
+			SearchIteratorV2Info: planSearchIteratorV2Info,
 		},
 		offset:     offset,
 		isIterator: isIterator,

internal/proxy/task.go

@@ -69,6 +69,11 @@ const (
 	OffsetKey            = "offset"
 	LimitKey             = "limit"
 
+	SearchIterV2Key        = "search_iter_v2"
+	SearchIterBatchSizeKey = "search_iter_batch_size"
+	SearchIterLastBoundKey = "search_iter_last_bound"
+	SearchIterIdKey        = "search_iter_id"
+
 	InsertTaskName                = "InsertTask"
 	CreateCollectionTaskName      = "CreateCollectionTask"
 	DropCollectionTaskName        = "DropCollectionTask"

internal/proxy/task_search.go

@@ -28,6 +28,7 @@ import (
 	"github.com/milvus-io/milvus/pkg/util/commonpbutil"
 	"github.com/milvus-io/milvus/pkg/util/funcutil"
 	"github.com/milvus-io/milvus/pkg/util/merr"
+	"github.com/milvus-io/milvus/pkg/util/metric"
 	"github.com/milvus-io/milvus/pkg/util/paramtable"
 	"github.com/milvus-io/milvus/pkg/util/timerecord"
 	"github.com/milvus-io/milvus/pkg/util/tsoutil"
@@ -590,12 +591,15 @@ func (t *searchTask) Execute(ctx context.Context) error {
 	return nil
 }
 
-func (t *searchTask) reduceResults(ctx context.Context, toReduceResults []*internalpb.SearchResults, nq, topK int64, offset int64, queryInfo *planpb.QueryInfo, isAdvance bool) (*milvuspb.SearchResults, error) {
+func getMetricType(toReduceResults []*internalpb.SearchResults) string {
 	metricType := ""
 	if len(toReduceResults) >= 1 {
 		metricType = toReduceResults[0].GetMetricType()
 	}
+	return metricType
+}
 
+func (t *searchTask) reduceResults(ctx context.Context, toReduceResults []*internalpb.SearchResults, nq, topK int64, offset int64, metricType string, queryInfo *planpb.QueryInfo, isAdvance bool) (*milvuspb.SearchResults, error) {
 	ctx, sp := otel.Tracer(typeutil.ProxyRole).Start(ctx, "reduceResults")
 	defer sp.End()
 
@@ -631,6 +635,24 @@ func (t *searchTask) reduceResults(ctx context.Context, toReduceResults []*inter
 	return result, nil
 }
 
+// find the last bound based on reduced results and metric type
+// only support nq == 1, for search iterator v2
+func getLastBound(result *milvuspb.SearchResults, incomingLastBound *float32, metricType string) float32 {
+	len := len(result.Results.Scores)
+	if len > 0 && result.GetResults().GetNumQueries() == 1 {
+		return result.Results.Scores[len-1]
+	}
+	// if no results found and incoming last bound is not nil, return it
+	if incomingLastBound != nil {
+		return *incomingLastBound
+	}
+	// if no results found and it is the first call, return the closest bound
+	if metric.PositivelyRelated(metricType) {
+		return math.MaxFloat32
+	}
+	return -math.MaxFloat32
+}
+
 func (t *searchTask) PostExecute(ctx context.Context) error {
 	ctx, sp := otel.Tracer(typeutil.ProxyRole).Start(ctx, "Proxy-Search-PostExecute")
 	defer sp.End()
@@ -670,6 +692,7 @@ func (t *searchTask) PostExecute(ctx context.Context) error {
 		return err
 	}
 
+	metricType := getMetricType(toReduceResults)
 	// reduce
 	if t.SearchRequest.GetIsAdvanced() {
 		multipleInternalResults := make([][]*internalpb.SearchResults, len(t.SearchRequest.GetSubReqs()))
@@ -696,16 +719,12 @@ func (t *searchTask) PostExecute(ctx context.Context) error {
 		multipleMilvusResults := make([]*milvuspb.SearchResults, len(t.SearchRequest.GetSubReqs()))
 		for index, internalResults := range multipleInternalResults {
 			subReq := t.SearchRequest.GetSubReqs()[index]
-
+			subMetricType := getMetricType(internalResults)
-			metricType := ""
+			result, err := t.reduceResults(t.ctx, internalResults, subReq.GetNq(), subReq.GetTopk(), subReq.GetOffset(), subMetricType, t.queryInfos[index], true)
-			if len(internalResults) >= 1 {
-				metricType = internalResults[0].GetMetricType()
-			}
-			result, err := t.reduceResults(t.ctx, internalResults, subReq.GetNq(), subReq.GetTopk(), subReq.GetOffset(), t.queryInfos[index], true)
 			if err != nil {
 				return err
 			}
-			t.reScorers[index].setMetricType(metricType)
+			t.reScorers[index].setMetricType(subMetricType)
 			t.reScorers[index].reScore(result)
 			multipleMilvusResults[index] = result
 		}
@@ -721,7 +740,7 @@ func (t *searchTask) PostExecute(ctx context.Context) error {
 			return err
 		}
 	} else {
-		t.result, err = t.reduceResults(t.ctx, toReduceResults, t.SearchRequest.GetNq(), t.SearchRequest.GetTopk(), t.SearchRequest.GetOffset(), t.queryInfos[0], false)
+		t.result, err = t.reduceResults(t.ctx, toReduceResults, t.SearchRequest.GetNq(), t.SearchRequest.GetTopk(), t.SearchRequest.GetOffset(), metricType, t.queryInfos[0], false)
 		if err != nil {
 			return err
 		}
@@ -751,6 +770,14 @@ func (t *searchTask) PostExecute(ctx context.Context) error {
 	}
 	t.result.Results.OutputFields = t.userOutputFields
 	t.result.CollectionName = t.request.GetCollectionName()
+	if t.isIterator && len(t.queryInfos) == 1 && t.queryInfos[0] != nil {
+		if iterInfo := t.queryInfos[0].GetSearchIteratorV2Info(); iterInfo != nil {
+			t.result.Results.SearchIteratorV2Results = &schemapb.SearchIteratorV2Results{
+				Token:     iterInfo.GetToken(),
+				LastBound: getLastBound(t.result, iterInfo.LastBound, metricType),
+			}
+		}
+	}
 	if t.isIterator && t.request.GetGuaranteeTimestamp() == 0 {
 		// first page for iteration, need to set up sessionTs for iterator
 		t.result.SessionTs = getMaxMvccTsFromChannels(t.queryChannelsTs, t.BeginTs())

internal/proxy/task_search_test.go

@@ -18,12 +18,14 @@ package proxy
 import (
 	"context"
 	"fmt"
+	"math"
 	"strconv"
 	"strings"
 	"testing"
 	"time"
 
 	"github.com/cockroachdb/errors"
+	"github.com/google/uuid"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/mock"
 	"github.com/stretchr/testify/require"
@@ -103,9 +105,124 @@ func TestSearchTask_PostExecute(t *testing.T) {
 		assert.Equal(t, qt.resultSizeInsufficient, true)
 		assert.Equal(t, qt.isTopkReduce, false)
 	})
+
+	t.Run("test search iterator v2", func(t *testing.T) {
+		const (
+			kRows  = 10
+			kToken = "test-token"
+		)
+
+		collName := "test_collection_search_iterator_v2" + funcutil.GenRandomStr()
+		collSchema := createColl(t, collName, rc)
+
+		createIteratorSearchTask := func(t *testing.T, metricType string, rows int) *searchTask {
+			ids := make([]int64, rows)
+			for i := range ids {
+				ids[i] = int64(i)
+			}
+			resultIDs := &schemapb.IDs{
+				IdField: &schemapb.IDs_IntId{
+					IntId: &schemapb.LongArray{
+						Data: ids,
+					},
+				},
+			}
+			scores := make([]float32, rows)
+			// proxy needs to reverse the score for negatively related metrics
+			for i := range scores {
+				if metric.PositivelyRelated(metricType) {
+					scores[i] = float32(len(scores) - i)
+				} else {
+					scores[i] = -float32(i + 1)
+				}
+			}
+			resultData := &schemapb.SearchResultData{
+				Ids:        resultIDs,
+				Scores:     scores,
+				NumQueries: 1,
+			}
+
+			qt := &searchTask{
+				ctx: ctx,
+				SearchRequest: &internalpb.SearchRequest{
+					Base: &commonpb.MsgBase{
+						MsgType:  commonpb.MsgType_Search,
+						SourceID: paramtable.GetNodeID(),
+					},
+					Nq: 1,
+				},
+				schema: newSchemaInfo(collSchema),
+				request: &milvuspb.SearchRequest{
+					CollectionName: collName,
+				},
+				queryInfos: []*planpb.QueryInfo{{
+					SearchIteratorV2Info: &planpb.SearchIteratorV2Info{
+						Token:     kToken,
+						BatchSize: 1,
+					},
+				}},
+				result: &milvuspb.SearchResults{
+					Results: resultData,
+				},
+				resultBuf:  typeutil.NewConcurrentSet[*internalpb.SearchResults](),
+				tr:         timerecord.NewTimeRecorder("search"),
+				isIterator: true,
+			}
+			bytes, err := proto.Marshal(resultData)
+			assert.NoError(t, err)
+			qt.resultBuf.Insert(&internalpb.SearchResults{
+				MetricType: metricType,
+				SlicedBlob: bytes,
+			})
+			return qt
+		}
+
+		t.Run("test search iterator v2", func(t *testing.T) {
+			metrics := []string{metric.L2, metric.IP, metric.COSINE, metric.BM25}
+			for _, metricType := range metrics {
+				qt := createIteratorSearchTask(t, metricType, kRows)
+				err = qt.PostExecute(ctx)
+				assert.NoError(t, err)
+				assert.Equal(t, kToken, qt.result.Results.SearchIteratorV2Results.Token)
+				if metric.PositivelyRelated(metricType) {
+					assert.Equal(t, float32(1), qt.result.Results.SearchIteratorV2Results.LastBound)
+				} else {
+					assert.Equal(t, float32(kRows), qt.result.Results.SearchIteratorV2Results.LastBound)
+				}
+			}
+		})
+
+		t.Run("test search iterator v2 with empty result", func(t *testing.T) {
+			metrics := []string{metric.L2, metric.IP, metric.COSINE, metric.BM25}
+			for _, metricType := range metrics {
+				qt := createIteratorSearchTask(t, metricType, 0)
+				err = qt.PostExecute(ctx)
+				assert.NoError(t, err)
+				assert.Equal(t, kToken, qt.result.Results.SearchIteratorV2Results.Token)
+				if metric.PositivelyRelated(metricType) {
+					assert.Equal(t, float32(math.MaxFloat32), qt.result.Results.SearchIteratorV2Results.LastBound)
+				} else {
+					assert.Equal(t, float32(-math.MaxFloat32), qt.result.Results.SearchIteratorV2Results.LastBound)
+				}
+			}
+		})
+
+		t.Run("test search iterator v2 with empty result and incoming last bound", func(t *testing.T) {
+			metrics := []string{metric.L2, metric.IP, metric.COSINE, metric.BM25}
+			kLastBound := float32(10)
+			for _, metricType := range metrics {
+				qt := createIteratorSearchTask(t, metricType, 0)
+				qt.queryInfos[0].SearchIteratorV2Info.LastBound = &kLastBound
+				err = qt.PostExecute(ctx)
+				assert.NoError(t, err)
+				assert.Equal(t, kToken, qt.result.Results.SearchIteratorV2Results.Token)
+				assert.Equal(t, kLastBound, qt.result.Results.SearchIteratorV2Results.LastBound)
+			}
+		})
+	})
 }
 
-func createColl(t *testing.T, name string, rc types.RootCoordClient) {
+func createColl(t *testing.T, name string, rc types.RootCoordClient) *schemapb.CollectionSchema {
 	schema := constructCollectionSchema(testInt64Field, testFloatVecField, testVecDim, name)
 	marshaledSchema, err := proto.Marshal(schema)
 	require.NoError(t, err)
@@ -126,6 +243,8 @@ func createColl(t *testing.T, name string, rc types.RootCoordClient) {
 	require.NoError(t, createColT.PreExecute(ctx))
 	require.NoError(t, createColT.Execute(ctx))
 	require.NoError(t, createColT.PostExecute(ctx))
+
+	return schema
 }
 
 func getBaseSearchParams() []*commonpb.KeyValuePair {
@@ -2599,6 +2718,157 @@ func TestTaskSearch_parseSearchInfo(t *testing.T) {
 			assert.True(t, strings.Contains(searchInfo.parseError.Error(), "failed to parse input group size"))
 		}
 	})
+
+	t.Run("check search iterator v2", func(t *testing.T) {
+		kBatchSize := uint32(10)
+		generateValidParamsForSearchIteratorV2 := func() []*commonpb.KeyValuePair {
+			param := getValidSearchParams()
+			return append(param,
+				&commonpb.KeyValuePair{
+					Key:   SearchIterV2Key,
+					Value: "True",
+				},
+				&commonpb.KeyValuePair{
+					Key:   IteratorField,
+					Value: "True",
+				},
+				&commonpb.KeyValuePair{
+					Key:   SearchIterBatchSizeKey,
+					Value: fmt.Sprintf("%d", kBatchSize),
+				},
+			)
+		}
+
+		t.Run("iteratorV2 normal", func(t *testing.T) {
+			param := generateValidParamsForSearchIteratorV2()
+			searchInfo := parseSearchInfo(param, nil, nil)
+			assert.NoError(t, searchInfo.parseError)
+			assert.NotNil(t, searchInfo.planInfo)
+			assert.NotEmpty(t, searchInfo.planInfo.SearchIteratorV2Info.Token)
+			assert.Equal(t, kBatchSize, searchInfo.planInfo.SearchIteratorV2Info.BatchSize)
+			assert.Len(t, searchInfo.planInfo.SearchIteratorV2Info.Token, 36)
+			assert.Equal(t, int64(kBatchSize), searchInfo.planInfo.GetTopk()) // compatibility
+		})
+
+		t.Run("iteratorV2 without isIterator", func(t *testing.T) {
+			param := generateValidParamsForSearchIteratorV2()
+			resetSearchParamsValue(param, IteratorField, "False")
+			searchInfo := parseSearchInfo(param, nil, nil)
+			assert.Error(t, searchInfo.parseError)
+			assert.ErrorContains(t, searchInfo.parseError, "both")
+		})
+
+		t.Run("iteratorV2 with groupBy", func(t *testing.T) {
+			param := generateValidParamsForSearchIteratorV2()
+			param = append(param, &commonpb.KeyValuePair{
+				Key:   GroupByFieldKey,
+				Value: "string_field",
+			})
+			fields := make([]*schemapb.FieldSchema, 0)
+			fields = append(fields, &schemapb.FieldSchema{
+				FieldID: int64(101),
+				Name:    "string_field",
+			})
+			schema := &schemapb.CollectionSchema{
+				Fields: fields,
+			}
+			searchInfo := parseSearchInfo(param, schema, nil)
+			assert.Error(t, searchInfo.parseError)
+			assert.ErrorContains(t, searchInfo.parseError, "roupBy")
+		})
+
+		t.Run("iteratorV2 with offset", func(t *testing.T) {
+			param := generateValidParamsForSearchIteratorV2()
+			param = append(param, &commonpb.KeyValuePair{
+				Key:   OffsetKey,
+				Value: "10",
+			})
+			searchInfo := parseSearchInfo(param, nil, nil)
+			assert.Error(t, searchInfo.parseError)
+			assert.ErrorContains(t, searchInfo.parseError, "offset")
+		})
+
+		t.Run("iteratorV2 invalid token", func(t *testing.T) {
+			param := generateValidParamsForSearchIteratorV2()
+			param = append(param, &commonpb.KeyValuePair{
+				Key:   SearchIterIdKey,
+				Value: "invalid_token",
+			})
+			searchInfo := parseSearchInfo(param, nil, nil)
+			assert.Error(t, searchInfo.parseError)
+			assert.ErrorContains(t, searchInfo.parseError, "invalid token format")
+		})
+
+		t.Run("iteratorV2 passed token must be same", func(t *testing.T) {
+			token, err := uuid.NewRandom()
+			assert.NoError(t, err)
+			param := generateValidParamsForSearchIteratorV2()
+			param = append(param, &commonpb.KeyValuePair{
+				Key:   SearchIterIdKey,
+				Value: token.String(),
+			})
+			searchInfo := parseSearchInfo(param, nil, nil)
+			assert.NoError(t, searchInfo.parseError)
+			assert.NotEmpty(t, searchInfo.planInfo.SearchIteratorV2Info.Token)
+			assert.Equal(t, token.String(), searchInfo.planInfo.SearchIteratorV2Info.Token)
+		})
+
+		t.Run("iteratorV2 batch size", func(t *testing.T) {
+			param := generateValidParamsForSearchIteratorV2()
+			resetSearchParamsValue(param, SearchIterBatchSizeKey, "1.123")
+			searchInfo := parseSearchInfo(param, nil, nil)
+			assert.Error(t, searchInfo.parseError)
+			assert.ErrorContains(t, searchInfo.parseError, "batch size is invalid")
+		})
+
+		t.Run("iteratorV2 batch size", func(t *testing.T) {
+			param := generateValidParamsForSearchIteratorV2()
+			resetSearchParamsValue(param, SearchIterBatchSizeKey, "")
+			searchInfo := parseSearchInfo(param, nil, nil)
+			assert.Error(t, searchInfo.parseError)
+			assert.ErrorContains(t, searchInfo.parseError, "batch size is required")
+		})
+
+		t.Run("iteratorV2 batch size negative", func(t *testing.T) {
+			param := generateValidParamsForSearchIteratorV2()
+			resetSearchParamsValue(param, SearchIterBatchSizeKey, "-1")
+			searchInfo := parseSearchInfo(param, nil, nil)
+			assert.Error(t, searchInfo.parseError)
+			assert.ErrorContains(t, searchInfo.parseError, "batch size is invalid")
+		})
+
+		t.Run("iteratorV2 batch size too large", func(t *testing.T) {
+			param := generateValidParamsForSearchIteratorV2()
+			resetSearchParamsValue(param, SearchIterBatchSizeKey, fmt.Sprintf("%d", Params.QuotaConfig.TopKLimit.GetAsInt64()+1))
+			searchInfo := parseSearchInfo(param, nil, nil)
+			assert.Error(t, searchInfo.parseError)
+			assert.ErrorContains(t, searchInfo.parseError, "batch size is invalid")
+		})
+
+		t.Run("iteratorV2 last bound", func(t *testing.T) {
+			kLastBound := float32(1.123)
+			param := generateValidParamsForSearchIteratorV2()
+			param = append(param, &commonpb.KeyValuePair{
+				Key:   SearchIterLastBoundKey,
+				Value: fmt.Sprintf("%f", kLastBound),
+			})
+			searchInfo := parseSearchInfo(param, nil, nil)
+			assert.NoError(t, searchInfo.parseError)
+			assert.NotNil(t, searchInfo.planInfo)
+			assert.Equal(t, kLastBound, *searchInfo.planInfo.SearchIteratorV2Info.LastBound)
+		})
+
+		t.Run("iteratorV2 invalid last bound", func(t *testing.T) {
+			param := generateValidParamsForSearchIteratorV2()
+			param = append(param, &commonpb.KeyValuePair{
+				Key:   SearchIterLastBoundKey,
+				Value: "xxx",
+			})
+			searchInfo := parseSearchInfo(param, nil, nil)
+			assert.Error(t, searchInfo.parseError)
+			assert.ErrorContains(t, searchInfo.parseError, "failed to parse input last bound")
+		})
+	})
 }
 
 func getSearchResultData(nq, topk int64) *schemapb.SearchResultData {