enhance: parallelize json stats build (#52120)

issue: #53765

JSON stats build benchmark — 500K rows per segment
Concurrent segments || Non-parallel || 8 workers || Speedup
1 || 6.810 s || 1.641 s || 4.15× faster
4 || 7.140 s || 4.806 s || 1.49× faster
8 || 10.878 s || 9.658 s || 1.13× faster
Setup: Release build, 12 CPUs, local filesystem, one warm-up followed by
five measured runs; median values are reported. Data generation is
excluded from the timing.
Note: “Non-parallel” means each segment is built serially internally.
Multiple segment builds are still launched concurrently in 8-segment
cases.

Signed-off-by: luzhang <[email protected]>
Co-authored-by: luzhang <[email protected]>

configs/milvus.yaml

@@ -999,7 +999,7 @@ dataCoord:
     analyzeTaskSlotUsage: 65535 # slot usage of analyze task
   jsonShreddingMaxColumns: 1024 # the max number of columns to shred
   jsonShreddingRatioThreshold: 0.3 # the ratio threshold to shred
-  jsonShreddingWriteBatchSize: 81920 # the batch size to write
+  jsonShreddingWriteBatchSize: 81920 # the batch size to write; values must be positive, otherwise the default is used
   ip:  # TCP/IP address of dataCoord. If not specified, use the first unicastable address
   port: 13333 # TCP port of dataCoord
   grpc:
@@ -1079,6 +1079,10 @@ dataNode:
   storage:
     format: parquet # storage format for insert data, options: [parquet, vortex]
     deltalog: json # deltalog format, options: [json, parquet]
+  jsonStats:
+    parallelBuild:
+      maxWorkers: 8 # Maximum number of process-wide JSON Stats Build workers. The effective value is capped by the cgroup-aware CPU count. Values less than or equal to 0 use the safe automatic limit min(CPU, 8).
+      maxInflightBytes: 536870912 # Process-wide transient memory budget in bytes for materialized JSON Stats Build chunks. The budget is shared by concurrent builds. Lower values reduce peak memory at the cost of parallelism. A chunk larger than the budget is allowed to run exclusively to guarantee progress. Set to 0 to disable the limit.
   ip:  # TCP/IP address of dataNode. If not specified, use the first unicastable address
   port: 21124 # TCP port of dataNode
   grpc:

internal/core/src/futures/Executor.cpp

@@ -10,7 +10,9 @@
 // or implied. See the License for the specific language governing permissions and limitations under the License
 
 #include <algorithm>
+#include <cstddef>
 #include <memory>
+#include <utility>
 
 #include "Executor.h"
 #include "folly/executors/CPUThreadPoolExecutor.h"
@@ -20,6 +22,8 @@
 namespace milvus::futures {
 
 const int kNumPriority = 3;
+const int kJsonStatsBuildNumPriority = 1;
+const size_t kJsonStatsBuildMinThreads = 1;
 
 folly::CPUThreadPoolExecutor*
 getSearchCPUExecutor() {
@@ -41,9 +45,21 @@ getLoadCPUExecutor() {
     return &executor;
 }
 
+folly::CPUThreadPoolExecutor*
+getJsonStatsBuildExecutor() {
+    auto max_thread_num = static_cast<size_t>(std::max(1, milvus::CPU_NUM));
+    static folly::CPUThreadPoolExecutor executor(
+        std::pair<size_t, size_t>{max_thread_num, kJsonStatsBuildMinThreads},
+        folly::CPUThreadPoolExecutor::makeDefaultPriorityQueue(
+            kJsonStatsBuildNumPriority),
+        std::make_shared<folly::NamedThreadFactory>(
+            "MILVUS_JSON_STATS_BUILD_"));
+    return &executor;
+}
+
 folly::CPUThreadPoolExecutor*
 getGlobalCPUExecutor() {
     return getSearchCPUExecutor();
 }
 
-};  // namespace milvus::futures
+};  // namespace milvus::futures

internal/core/src/futures/Executor.h

@@ -33,4 +33,7 @@ getSearchCPUExecutor();
 folly::CPUThreadPoolExecutor*
 getLoadCPUExecutor();
 
+folly::CPUThreadPoolExecutor*
+getJsonStatsBuildExecutor();
+
 };  // namespace milvus::futures

internal/core/src/futures/FutureTest.cpp

@@ -16,6 +16,7 @@
 #include <stdlib.h>
 #include <chrono>
 #include <exception>
+#include <future>
 #include <memory>
 #include <mutex>
 #include <stdexcept>
@@ -27,14 +28,65 @@
 
 #include "common/EasyAssert.h"
 #include "common/common_type_c.h"
+#include "futures/Executor.h"
 #include "futures/Future.h"
 #include "futures/LeakyResult.h"
 #include "futures/Ready.h"
+#include "futures/future_c.h"
 #include "futures/future_c_types.h"
 #include "gtest/gtest.h"
+#include "index/json_stats/JsonStatsBuildMemoryBudget.h"
 
 using namespace milvus::futures;
 
+TEST(Futures, JsonStatsBuildExecutor) {
+    auto* executor = getJsonStatsBuildExecutor();
+
+    ASSERT_NE(executor, nullptr);
+    EXPECT_NE(executor, getSearchCPUExecutor());
+    EXPECT_NE(executor, getLoadCPUExecutor());
+    EXPECT_EQ(executor->getNumPriorities(), 1);
+    EXPECT_GE(executor->numThreads(), 1);
+
+    std::promise<std::thread::id> promise;
+    auto future = promise.get_future();
+    executor->add(
+        [&promise]() { promise.set_value(std::this_thread::get_id()); });
+
+    EXPECT_NE(future.get(), std::this_thread::get_id());
+}
+
+TEST(Futures, ResizeJsonStatsBuildExecutor) {
+    auto* executor = getJsonStatsBuildExecutor();
+    auto original_thread_num = executor->numThreads();
+
+    auto status = executor_set_json_stats_build_thread_num(3);
+    ASSERT_EQ(status.error_code, milvus::Success);
+    EXPECT_EQ(executor->numThreads(), 3);
+
+    status = executor_set_json_stats_build_thread_num(0);
+    ASSERT_EQ(status.error_code, milvus::Success);
+    EXPECT_EQ(executor->numThreads(), 1);
+
+    status = executor_set_json_stats_build_thread_num(
+        static_cast<int>(original_thread_num));
+    ASSERT_EQ(status.error_code, milvus::Success);
+}
+
+TEST(Futures, SetJsonStatsBuildMemoryBudget) {
+    auto& budget = milvus::index::JsonStatsBuildMemoryBudget::GetInstance();
+    auto original_capacity = budget.CapacityBytes();
+
+    auto status = executor_set_json_stats_build_max_inflight_bytes(1234);
+    EXPECT_EQ(status.error_code, milvus::Success);
+    EXPECT_EQ(budget.CapacityBytes(), 1234);
+
+    status = executor_set_json_stats_build_max_inflight_bytes(
+        static_cast<int64_t>(original_capacity));
+    EXPECT_EQ(status.error_code, milvus::Success);
+    EXPECT_EQ(budget.CapacityBytes(), original_capacity);
+}
+
 TEST(Futures, LeakyResult) {
     {
         LeakyResult<int> leaky_result;
@@ -225,4 +277,4 @@ TEST(Futures, Future) {
         ASSERT_EQ(s.error_code, milvus::FollyCancel);
         free((char*)(s.error_msg));
     }
-}
+}

internal/core/src/futures/future_c.cpp

@@ -9,6 +9,10 @@
 // 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 <algorithm>
+#include <exception>
+
+#include "common/EasyAssert.h"
 #include "Executor.h"
 #include "Future.h"
 #include "folly/executors/CPUThreadPoolExecutor.h"
@@ -16,6 +20,7 @@
 #include "common/CGoCatch.h"
 #include "futures/future_c_types.h"
 #include "glog/logging.h"
+#include "index/json_stats/JsonStatsBuildMemoryBudget.h"
 #include "log/Log.h"
 #include "monitor/Monitor.h"
 #include "prometheus/gauge.h"
@@ -82,3 +87,34 @@ executor_set_load_thread_num(int thread_num) {
     }
     CGO_CATCH_AND_LOG("executor_set_load_thread_num")
 }
+
+extern "C" CStatus
+executor_set_json_stats_build_thread_num(int thread_num) {
+    auto normalized_thread_num = std::max(1, thread_num);
+    try {
+        milvus::futures::getJsonStatsBuildExecutor()->setNumThreads(
+            normalized_thread_num);
+        LOG_INFO(
+            "future executor setup json stats build cpu executor with thread "
+            "num: {}",
+            normalized_thread_num);
+        return milvus::SuccessCStatus();
+    }
+    CGO_CATCH_AND_RETURN_CSTATUS
+}
+
+extern "C" CStatus
+executor_set_json_stats_build_max_inflight_bytes(int64_t max_inflight_bytes) {
+    try {
+        auto normalized_max_inflight_bytes =
+            static_cast<size_t>(std::max<int64_t>(0, max_inflight_bytes));
+        milvus::index::JsonStatsBuildMemoryBudget::GetInstance()
+            .SetCapacityBytes(normalized_max_inflight_bytes);
+        LOG_INFO(
+            "json stats build transient memory budget setup with max inflight "
+            "bytes: {}",
+            normalized_max_inflight_bytes);
+        return milvus::SuccessCStatus();
+    }
+    CGO_CATCH_AND_RETURN_CSTATUS
+}

internal/core/src/futures/future_c.h

@@ -14,6 +14,7 @@
 #include "common/common_type_c.h"
 #include "future_c_types.h"
 #include <stdbool.h>
+#include <stdint.h>
 
 #ifdef __cplusplus
 extern "C" {
@@ -46,6 +47,12 @@ executor_set_search_thread_num(int thread_num);
 void
 executor_set_load_thread_num(int thread_num);
 
+CStatus
+executor_set_json_stats_build_thread_num(int thread_num);
+
+CStatus
+executor_set_json_stats_build_max_inflight_bytes(int64_t max_inflight_bytes);
+
 #ifdef __cplusplus
 }
 #endif

internal/core/src/index/json_stats/JsonKeyStats.cpp

@@ -14,17 +14,21 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-#include <nlohmann/json.hpp>
-#include <string.h>
+#include <algorithm>
+#include <atomic>
 #include <chrono>
 #include <cstdint>
 #include <exception>
 #include <filesystem>
 #include <initializer_list>
 #include <iosfwd>
+#include <map>
+#include <memory>
+#include <string.h>
 #include <unordered_set>
+#include <utility>
 #include <variant>
-#include "segcore/default_fs.h"
+#include <vector>
 
 #include "NamedType/named_type_impl.hpp"
 #include "NamedType/underlying_functionalities.hpp"
@@ -38,12 +42,16 @@
 #include "common/GroupChunk.h"
 #include "common/Json.h"
 #include "common/Tracer.h"
+#include "common/Utils.h"
 #include "common/jsmn.h"
 #include "fmt/core.h"
 #include "folly/ScopeGuard.h"
 #include "folly/coro/BlockingWait.h"
+#include "folly/futures/Future.h"
+#include "futures/Executor.h"
 #include "index/Utils.h"
 #include "index/json_stats/JsonKeyStats.h"
+#include "index/json_stats/JsonStatsBuildMemoryBudget.h"
 #include "index/json_stats/bson_builder.h"
 #include "index/json_stats/parquet_writer.h"
 #include "milvus-storage/common/config.h"
@@ -57,15 +65,17 @@
 #include "milvus-storage/reader.h"
 #include "mmap/ChunkedColumnGroup.h"
 #include "mmap/Types.h"
+#include "nlohmann/json.hpp"
 #include "nlohmann/detail/iterators/iteration_proxy.hpp"
 #include "nlohmann/json_fwd.hpp"
 #include "parquet/metadata.h"
-#include "segcore/storagev1translator/BsonInvertedIndexTranslator.h"
 #include "segcore/ChunkedSegmentSealedImpl.h"
 #include "segcore/storagev2translator/AsyncChunkReader.h"
 #include "segcore/storagev2translator/ManifestGroupTranslator.h"
 #include "segcore/storagev2translator/StorageV2Config.h"
 #include "segcore/Utils.h"
+#include "segcore/default_fs.h"
+#include "segcore/storagev1translator/BsonInvertedIndexTranslator.h"
 #include "storage/DiskFileManagerImpl.h"
 #include "storage/FileManager.h"
 #include "storage/LocalChunkManager.h"
@@ -84,6 +94,88 @@ namespace {
 
 // Reader::create() exposes this synthetic JSON-stats group at index zero.
 constexpr int64_t kJsonStatsReaderColumnGroupIndex = 0;
+constexpr int64_t kJsonStatsRowsPerRange = 16 * 1024;
+constexpr size_t kJsonStatsMaterializeMinReservationBytes = 64 * 1024;
+constexpr size_t kJsonStatsMaterializeInputExpansionFactor = 2;
+constexpr size_t kJsonStatsMaterializeRowOverheadBytes = 32;
+constexpr size_t kJsonStatsMaterializeColumnOverheadBytes = 1024;
+
+struct CollectKeyInfoResult {
+    std::map<JsonKey, KeyStatsInfo> infos;
+};
+
+template <typename Func>
+void
+ForEachJsonStatsRow(const JsonStatsRowRange& range, Func&& func) {
+    int64_t visited_rows = 0;
+    for (const auto& slice : range.slices) {
+        AssertInfo(slice.data != nullptr,
+                   "json stats row range contains null field data");
+        AssertInfo(slice.row_count > 0,
+                   "json stats row range contains an empty slice");
+        AssertInfo(slice.local_begin >= 0,
+                   "json stats field data slice has negative local begin: {}",
+                   slice.local_begin);
+        AssertInfo(
+            slice.local_begin <= slice.data->get_num_rows() - slice.row_count,
+            "json stats field data slice [{}, {}) exceeds field data rows {}",
+            slice.local_begin,
+            slice.local_begin + slice.row_count,
+            slice.data->get_num_rows());
+        const auto slice_global_begin = range.global_begin + visited_rows;
+
+        for (int64_t offset = 0; offset < slice.row_count; ++offset) {
+            func(slice.data,
+                 slice.local_begin + offset,
+                 slice_global_begin + offset);
+        }
+        visited_rows += slice.row_count;
+    }
+    AssertInfo(visited_rows == range.row_count,
+               "json stats row range contains {} rows, expected {}",
+               visited_rows,
+               range.row_count);
+}
+
+size_t
+BytesForBits(size_t bit_count) {
+    return SaturatingAdd(bit_count / 8,
+                         bit_count % 8 == 0 ? size_t{0} : size_t{1});
+}
+
+size_t
+EstimateArrowFixedBufferBytes(const arrow::Schema& schema, size_t row_count) {
+    const auto validity_bytes = BytesForBits(row_count);
+    size_t buffer_bytes = 0;
+    for (const auto& field : schema.fields()) {
+        // Every materialized column can contain nulls. Account for its validity
+        // bitmap even when a dense finished array can omit that buffer.
+        buffer_bytes = SaturatingAdd(buffer_bytes, validity_bytes);
+
+        const auto& type = *field->type();
+        if (type.id() == arrow::Type::STRING ||
+            type.id() == arrow::Type::BINARY) {
+            // The variable payload is covered by the input-size estimate. This
+            // accounts for the offsets that are allocated even for null rows.
+            const auto offset_count = SaturatingAdd(row_count, size_t{1});
+            buffer_bytes = SaturatingAdd(
+                buffer_bytes,
+                SaturatingMultiply(offset_count,
+                                   sizeof(arrow::BinaryType::offset_type)));
+            continue;
+        }
+
+        const auto bit_width = type.bit_width();
+        AssertInfo(bit_width > 0,
+                   "unsupported json stats Arrow field type {}",
+                   type.ToString());
+        buffer_bytes =
+            SaturatingAdd(buffer_bytes,
+                          BytesForBits(SaturatingMultiply(
+                              row_count, static_cast<size_t>(bit_width))));
+    }
+    return buffer_bytes;
+}
 
 struct JsonStatsParquetMetadata {
     std::shared_ptr<arrow::Schema> schema;
@@ -205,6 +297,93 @@ GetJsonStatsFieldsFromSchema(const std::shared_ptr<arrow::Schema>& schema) {
 
 }  // namespace
 
+std::vector<JsonStatsRowRange>
+CreateJsonStatsRowRanges(const std::vector<FieldDataPtr>& field_datas,
+                         int64_t max_rows_per_range) {
+    AssertInfo(max_rows_per_range > 0,
+               "json stats max rows per range must be positive, got {}",
+               max_rows_per_range);
+
+    std::vector<JsonStatsRowRange> row_ranges;
+    JsonStatsRowRange current_range{};
+    int64_t global_begin = 0;
+
+    for (const auto& data : field_datas) {
+        AssertInfo(data != nullptr,
+                   "cannot create json stats row range from null field data");
+        const auto data_rows = data->get_num_rows();
+        AssertInfo(data_rows >= 0,
+                   "json stats field data has negative row count: {}",
+                   data_rows);
+
+        int64_t local_begin = 0;
+        while (local_begin < data_rows) {
+            if (current_range.row_count == 0) {
+                current_range.global_begin = global_begin + local_begin;
+            }
+
+            const auto remaining_rows =
+                max_rows_per_range - current_range.row_count;
+            const auto slice_rows =
+                std::min(data_rows - local_begin, remaining_rows);
+            current_range.slices.push_back(JsonStatsFieldDataSlice{
+                data,
+                local_begin,
+                slice_rows,
+            });
+            current_range.row_count += slice_rows;
+            local_begin += slice_rows;
+
+            if (current_range.row_count == max_rows_per_range) {
+                row_ranges.push_back(std::move(current_range));
+                current_range = JsonStatsRowRange{};
+            }
+        }
+        global_begin += data_rows;
+    }
+
+    if (current_range.row_count > 0) {
+        row_ranges.push_back(std::move(current_range));
+    }
+    return row_ranges;
+}
+
+size_t
+JsonKeyStats::EstimateJsonStatsMaterializeReservationBytes(
+    const JsonStatsRowRange& range, const arrow::Schema& schema) {
+    size_t input_bytes = 0;
+    ForEachJsonStatsRow(
+        range,
+        [&](const FieldDataPtr& data,
+            int64_t local_row,
+            int64_t /* global_row */) {
+            if (data->IsNullable() && !data->is_valid(local_row)) {
+                return;
+            }
+            auto raw_value = data->RawValue(local_row);
+            if (raw_value == nullptr) {
+                return;
+            }
+            const auto* json = static_cast<const milvus::Json*>(raw_value);
+            input_bytes = SaturatingAdd(input_bytes, json->data().size());
+        });
+
+    const auto row_count = static_cast<size_t>(range.row_count);
+    auto reservation_bytes = SaturatingMultiply(
+        input_bytes, kJsonStatsMaterializeInputExpansionFactor);
+    reservation_bytes = SaturatingAdd(
+        reservation_bytes,
+        SaturatingMultiply(row_count, kJsonStatsMaterializeRowOverheadBytes));
+    reservation_bytes = SaturatingAdd(
+        reservation_bytes,
+        SaturatingMultiply(static_cast<size_t>(schema.num_fields()),
+                           kJsonStatsMaterializeColumnOverheadBytes));
+    reservation_bytes = SaturatingAdd(
+        reservation_bytes, EstimateArrowFixedBufferBytes(schema, row_count));
+    return std::max(kJsonStatsMaterializeMinReservationBytes,
+                    reservation_bytes);
+}
+
 JsonKeyStats::JsonKeyStats(const storage::FileManagerContext& ctx,
                            bool is_load,
                            int64_t json_stats_max_shredding_columns,
@@ -221,7 +400,11 @@ JsonKeyStats::JsonKeyStats(const storage::FileManagerContext& ctx,
         std::make_shared<milvus::storage::MemFileManagerImpl>(ctx);
     disk_file_manager_ =
         std::make_shared<milvus::storage::DiskFileManagerImpl>(ctx);
-    write_batch_size_ = json_stats_write_batch_size;
+    // Older coordinators can send values that bypass the Go config formatter.
+    // Normalize before choosing row ranges or passing the value to the writer.
+    write_batch_size_ = json_stats_write_batch_size > 0
+                            ? json_stats_write_batch_size
+                            : kDefaultWriteBatchSize;
     max_shredding_columns_ = json_stats_max_shredding_columns;
     shredding_ratio_threshold_ = json_stats_shredding_ratio_threshold;
     LOG_INFO(
@@ -445,6 +628,100 @@ JsonKeyStats::CollectKeyInfo(const std::vector<FieldDataPtr>& field_datas,
     return infos;
 }
 
+std::map<JsonKey, KeyStatsInfo>
+JsonKeyStats::CollectKeyInfo(const std::vector<JsonStatsRowRange>& row_ranges,
+                             bool nullable) {
+    std::map<JsonKey, KeyStatsInfo> infos;
+    if (row_ranges.empty()) {
+        num_rows_ = 0;
+        return infos;
+    }
+
+    auto* executor = milvus::futures::getJsonStatsBuildExecutor();
+    const auto max_inflight = std::min(
+        row_ranges.size(), std::max<size_t>(1, executor->numThreads()));
+
+    // Futures are kept in range-index order. Only max_inflight tasks are active
+    // at a time, so completed local maps cannot accumulate for every range.
+    std::vector<folly::Future<CollectKeyInfoResult>> futures;
+    futures.reserve(row_ranges.size());
+    size_t next_submit = 0;
+    size_t next_consume = 0;
+    std::exception_ptr first_exception;
+
+    auto submit_next = [&]() {
+        try {
+            auto range = row_ranges[next_submit];
+            auto future = folly::via(
+                executor, [this, range = std::move(range), nullable]() {
+                    std::map<JsonKey, KeyStatsInfo> local_infos;
+                    ForEachJsonStatsRow(
+                        range,
+                        [&](const FieldDataPtr& data,
+                            int64_t local_row,
+                            int64_t /* global_row */) {
+                            if ((nullable || data->IsNullable()) &&
+                                !data->is_valid(local_row)) {
+                                return;
+                            }
+                            auto json_str = static_cast<const milvus::Json*>(
+                                                data->RawValue(local_row))
+                                                ->data();
+                            CollectSingleJsonStatsInfo(json_str, local_infos);
+                        });
+                    return CollectKeyInfoResult{std::move(local_infos)};
+                });
+            futures.emplace_back(std::move(future));
+            ++next_submit;
+        } catch (...) {
+            if (first_exception == nullptr) {
+                first_exception = std::current_exception();
+            }
+        }
+    };
+
+    while (next_submit < max_inflight && first_exception == nullptr) {
+        submit_next();
+    }
+
+    int64_t num_rows = 0;
+    while (next_consume < futures.size()) {
+        try {
+            auto result = std::move(futures[next_consume]).get();
+            if (first_exception == nullptr) {
+                const auto& range = row_ranges[next_consume];
+                AssertInfo(
+                    range.global_begin == num_rows,
+                    "json stats row range starts at global row {}, expected {}",
+                    range.global_begin,
+                    num_rows);
+                for (const auto& [key, local_info] : result.infos) {
+                    infos[key].hit_row_num_ += local_info.hit_row_num_;
+                }
+                num_rows += range.row_count;
+            }
+        } catch (...) {
+            if (first_exception == nullptr) {
+                first_exception = std::current_exception();
+            }
+        }
+        ++next_consume;
+
+        if (first_exception == nullptr && next_submit < row_ranges.size()) {
+            submit_next();
+        }
+    }
+
+    // Every submitted future has been consumed before an error escapes. This
+    // keeps `this` and the FieldData referenced by worker lambdas alive.
+    if (first_exception != nullptr) {
+        std::rethrow_exception(first_exception);
+    }
+
+    num_rows_ = num_rows;
+    return infos;
+}
+
 std::map<JsonKey, JsonKeyLayoutType>
 JsonKeyStats::ClassifyJsonKeyLayoutType(
     const std::map<JsonKey, KeyStatsInfo>& infos) {
@@ -551,7 +828,7 @@ void
 JsonKeyStats::AddKeyStats(const std::vector<std::string>& path,
                           JSONType type,
                           const std::string& value,
-                          std::map<JsonKey, std::string>& values) {
+                          std::map<JsonKey, std::string>& values) const {
     auto path_str = JsonPointer(path);
     auto key = JsonKey(path_str, type);
     values[key] = value;
@@ -563,7 +840,7 @@ JsonKeyStats::TraverseJsonForBuildStats(
     jsmntok* tokens,
     int& index,
     std::vector<std::string>& path,
-    std::map<JsonKey, std::string>& values) {
+    std::map<JsonKey, std::string>& values) const {
     jsmntok current = tokens[0];
     if (!(current.type != JSMN_UNDEFINED)) {
         ThrowInfo(ErrorCode::DataFormatBroken,
@@ -604,15 +881,7 @@ JsonKeyStats::TraverseJsonForBuildStats(
         index = j;
     } else if (current.type == JSMN_PRIMITIVE) {
         std::string value(json + current.start, current.end - current.start);
-        JSONType type;
-        try {
-            type = getType(value);
-        } catch (const std::exception& e) {
-            ThrowInfo(ErrorCode::DataFormatBroken,
-                      "failed to get json type for value: {} with error: {}",
-                      value,
-                      e.what());
-        }
+        auto type = getType(value);
 
         if (type == JSONType::INT64) {
             AddKeyStats(path, JSONType::INT64, value, values);
@@ -656,26 +925,9 @@ JsonKeyStats::TraverseJsonForBuildStats(
     }
 }
 
-void
-JsonKeyStats::BuildKeyStatsForNullRow() {
-    // add empty value for column keys that not hit
-    for (const auto& key : column_keys_) {
-        parquet_writer_->AppendValue(key.ToColumnName(), "");
-    }
-
-    // add null bson to shared column
-    BsonDocument null_doc;
-    parquet_writer_->AppendSharedRow(null_doc.data(), null_doc.length());
-
-    parquet_writer_->AddCurrentRow();
-}
-
-void
-JsonKeyStats::BuildKeyStatsForRow(std::string_view json_str, uint32_t row_id) {
-    LOG_TRACE("build key stats for row {} with json {} for segment {}",
-              row_id,
-              json_str,
-              segment_id_);
+bool
+JsonKeyStats::ParseJsonForBuildStats(
+    std::string_view json_str, std::map<JsonKey, std::string>& values) const {
     jsmn_parser parser;
     jsmn_init(&parser);
 
@@ -691,30 +943,56 @@ JsonKeyStats::BuildKeyStatsForRow(std::string_view json_str, uint32_t row_id) {
                            token_capacity);
         if (r < 0) {
             if (r == JSMN_ERROR_NOMEM) {
-                // Reallocate tokens array if not enough space
                 token_capacity *= 2;
                 tokens.resize(token_capacity);
                 continue;
-            } else {
-                ThrowInfo(ErrorCode::DataFormatBroken,
-                          "Failed to parse Json: {}, error: {}",
-                          json_str,
-                          int(r));
             }
+            ThrowInfo(ErrorCode::DataFormatBroken,
+                      "Failed to parse Json: {}, error: {}",
+                      json_str,
+                      int(r));
         }
         num_tokens = r;
         break;
     }
 
     if (num_tokens == 0) {
-        return;
+        return false;
     }
 
     int index = 0;
     std::vector<std::string> paths;
-    std::map<JsonKey, std::string> values;
     TraverseJsonForBuildStats(
         json_str.data(), tokens.data(), index, paths, values);
+    return true;
+}
+
+void
+JsonKeyStats::BuildKeyStatsForNullRow() {
+    // add empty value for column keys that not hit
+    for (const auto& key : column_keys_) {
+        parquet_writer_->AppendValue(key.ToColumnName(), "");
+    }
+
+    // add an empty BSON document to the shared column
+    BsonDocument null_doc;
+    parquet_writer_->AppendSharedRow(null_doc.data(), null_doc.length());
+
+    parquet_writer_->AddCurrentRow();
+}
+
+void
+JsonKeyStats::BuildKeyStatsForRow(std::string_view json_str, uint32_t row_id) {
+    LOG_TRACE("build key stats for row {} with json {} for segment {}",
+              row_id,
+              json_str,
+              segment_id_);
+    std::map<JsonKey, std::string> values;
+    if (!ParseJsonForBuildStats(json_str, values)) {
+        BuildKeyStatsForNullRow();
+        return;
+    }
+
     DomNode root;
     std::set<JsonKey> hit_keys;
     for (const auto& [key, value] : values) {
@@ -769,29 +1047,430 @@ JsonKeyStats::BuildKeyStatsForRow(std::string_view json_str, uint32_t row_id) {
 }
 
 void
-JsonKeyStats::BuildKeyStats(const std::vector<FieldDataPtr>& field_datas,
+JsonKeyStats::BuildKeyStats(const std::vector<JsonStatsRowRange>& row_ranges,
                             bool nullable) {
-    uint32_t row_id = 0;
-    for (const auto& data : field_datas) {
-        auto n = data->get_num_rows();
-        for (uint32_t i = 0; i < n; i++) {
-            if ((nullable || data->IsNullable()) && !data->is_valid(i)) {
-                BuildKeyStatsForNullRow();
-            } else {
-                auto json_str =
-                    static_cast<const milvus::Json*>(data->RawValue(i))->data();
-
-                // some situations, such as empty json string,
-                // should be handled as null row
-                if (json_str.empty()) {
+    int64_t processed_rows = 0;
+    for (const auto& range : row_ranges) {
+        AssertInfo(range.global_begin == processed_rows,
+                   "json stats row range starts at global row {}, expected {}",
+                   range.global_begin,
+                   processed_rows);
+        ForEachJsonStatsRow(
+            range,
+            [&](const FieldDataPtr& data,
+                int64_t local_row,
+                int64_t global_row) {
+                if ((nullable || data->IsNullable()) &&
+                    !data->is_valid(local_row)) {
                     BuildKeyStatsForNullRow();
                 } else {
-                    BuildKeyStatsForRow(json_str, row_id);
+                    auto json_str = static_cast<const milvus::Json*>(
+                                        data->RawValue(local_row))
+                                        ->data();
+
+                    // some situations, such as empty json string,
+                    // should be handled as null row
+                    if (json_str.empty()) {
+                        BuildKeyStatsForNullRow();
+                    } else {
+                        BuildKeyStatsForRow(json_str,
+                                            static_cast<uint32_t>(global_row));
+                    }
                 }
-            }
-            row_id++;
+            });
+        processed_rows += range.row_count;
+    }
+    AssertInfo(processed_rows == num_rows_,
+               "materialized {} json stats rows, expected {}",
+               processed_rows,
+               num_rows_);
+}
+
+JsonKeyStats::MaterializedChunk
+JsonKeyStats::MaterializeKeyStatsRange(
+    const JsonStatsRowRange& range,
+    bool nullable,
+    const std::shared_ptr<arrow::Schema>& schema) const {
+    AssertInfo(schema != nullptr,
+               "json stats materialize schema must not be null");
+
+    auto [builders, builders_map] = CreateArrowBuildersForColumns(column_keys_);
+    AssertInfo(
+        builders.size() == static_cast<size_t>(schema->num_fields()),
+        "json stats materialize builder count {} does not match schema field "
+        "count {}",
+        builders.size(),
+        schema->num_fields());
+    // Match the pre-dispatch fixed-buffer estimate and avoid geometric
+    // over-allocation while appending a partially filled final range.
+    for (const auto& builder : builders) {
+        auto status = builder->Reserve(range.row_count);
+        if (!status.ok()) {
+            ThrowInfo(milvus::storage::ArrowStatusToErrorCode(status),
+                      "failed to reserve json stats builder for {} rows: {}",
+                      range.row_count,
+                      status.ToString());
         }
     }
+
+    std::map<std::string, std::vector<int64_t>> bson_postings;
+    auto append_null_row = [&]() {
+        for (size_t i = 0; i + 1 < builders.size(); ++i) {
+            auto status = builders[i]->AppendNull();
+            if (!status.ok()) {
+                ThrowInfo(milvus::storage::ArrowStatusToErrorCode(status),
+                          "failed to append null json stats value: {}",
+                          status.ToString());
+            }
+        }
+
+        BsonDocument null_doc;
+        auto shared_builder =
+            std::static_pointer_cast<arrow::BinaryBuilder>(builders.back());
+        auto status =
+            shared_builder->Append(null_doc.data(), null_doc.length());
+        if (!status.ok()) {
+            ThrowInfo(milvus::storage::ArrowStatusToErrorCode(status),
+                      "failed to append empty shared json stats value: {}",
+                      status.ToString());
+        }
+    };
+
+    ForEachJsonStatsRow(
+        range,
+        [&](const FieldDataPtr& data, int64_t local_row, int64_t global_row) {
+            if ((nullable || data->IsNullable()) &&
+                !data->is_valid(local_row)) {
+                append_null_row();
+                return;
+            }
+
+            auto json_str =
+                static_cast<const milvus::Json*>(data->RawValue(local_row))
+                    ->data();
+            if (json_str.empty()) {
+                append_null_row();
+                return;
+            }
+
+            LOG_TRACE(
+                "materialize key stats for row {} with json {} for "
+                "segment {}",
+                global_row,
+                json_str,
+                segment_id_);
+            std::map<JsonKey, std::string> values;
+            if (!ParseJsonForBuildStats(json_str, values)) {
+                append_null_row();
+                return;
+            }
+
+            DomNode root;
+            std::set<JsonKey> hit_keys;
+            for (const auto& [key, value] : values) {
+                auto key_type = key_types_.find(key);
+                AssertInfo(key_type != key_types_.end(),
+                           "key {} not found in key types",
+                           key.key_);
+                if (key_type->second == JsonKeyLayoutType::SHARED) {
+                    auto path_vec = ParseJsonPointerPath(key.key_);
+                    BsonBuilder::AppendToDom(root, path_vec, value, key.type_);
+                } else {
+                    auto builder = builders_map.find(key.ToColumnName());
+                    AssertInfo(builder != builders_map.end(),
+                               "builder for key {} not found",
+                               key.ToColumnName());
+
+                    arrow::Status status;
+                    if (key.type_ == JSONType::ARRAY) {
+                        auto bson_bytes =
+                            BuildBsonArrayBytesFromJsonString(value);
+                        status = AppendJsonStatsValueToBuilder(
+                            std::string(reinterpret_cast<const char*>(
+                                            bson_bytes.data()),
+                                        bson_bytes.size()),
+                            builder->second);
+                    } else {
+                        status = AppendJsonStatsValueToBuilder(value,
+                                                               builder->second);
+                    }
+                    if (!status.ok()) {
+                        ThrowInfo(
+                            milvus::storage::ArrowStatusToErrorCode(status),
+                            "failed to append json stats value for key {}: {}",
+                            key.ToColumnName(),
+                            status.ToString());
+                    }
+                }
+                hit_keys.insert(key);
+            }
+
+            for (const auto& key : column_keys_) {
+                if (hit_keys.find(key) != hit_keys.end()) {
+                    continue;
+                }
+                auto builder = builders_map.find(key.ToColumnName());
+                AssertInfo(builder != builders_map.end(),
+                           "builder for key {} not found",
+                           key.ToColumnName());
+                auto status = builder->second->AppendNull();
+                if (!status.ok()) {
+                    ThrowInfo(milvus::storage::ArrowStatusToErrorCode(status),
+                              "failed to append null json stats value for key "
+                              "{}: {}",
+                              key.ToColumnName(),
+                              status.ToString());
+                }
+            }
+
+            BsonDocument final_doc;
+            BsonBuilder::ConvertDomToBson(root, final_doc.get());
+            auto key_offsets = BsonBuilder::ExtractBsonKeyOffsets(
+                final_doc.data(), final_doc.length());
+            for (const auto& [key, offset] : key_offsets) {
+                bson_postings[key].push_back(EncodeInvertedIndexValue(
+                    static_cast<uint32_t>(global_row), offset));
+            }
+
+            auto shared_builder =
+                std::static_pointer_cast<arrow::BinaryBuilder>(builders.back());
+            auto status =
+                shared_builder->Append(final_doc.data(), final_doc.length());
+            if (!status.ok()) {
+                ThrowInfo(milvus::storage::ArrowStatusToErrorCode(status),
+                          "failed to append shared json stats value: {}",
+                          status.ToString());
+            }
+        });
+
+    std::vector<std::shared_ptr<arrow::Array>> arrays;
+    arrays.reserve(builders.size());
+    for (const auto& builder : builders) {
+        AssertInfo(builder->length() == range.row_count,
+                   "json stats materialize builder contains {} rows, "
+                   "expected {}",
+                   builder->length(),
+                   range.row_count);
+        std::shared_ptr<arrow::Array> array;
+        auto status = builder->Finish(&array);
+        if (!status.ok()) {
+            ThrowInfo(milvus::storage::ArrowStatusToErrorCode(status),
+                      "failed to finish json stats materialize builder: {}",
+                      status.ToString());
+        }
+        arrays.push_back(std::move(array));
+    }
+
+    auto record_batch =
+        arrow::RecordBatch::Make(schema, range.row_count, std::move(arrays));
+    auto validate_status = record_batch->Validate();
+    if (!validate_status.ok()) {
+        ThrowInfo(milvus::storage::ArrowStatusToErrorCode(validate_status),
+                  "invalid materialized json stats record batch: {}",
+                  validate_status.ToString());
+    }
+
+    size_t materialized_bytes = sizeof(MaterializedChunk);
+    for (const auto& array : record_batch->columns()) {
+        materialized_bytes =
+            SaturatingAdd(materialized_bytes, GetArrowArrayMemorySize(array));
+        materialized_bytes = SaturatingAdd(
+            materialized_bytes, sizeof(std::shared_ptr<arrow::Array>));
+    }
+    for (const auto& [key, postings] : bson_postings) {
+        materialized_bytes = SaturatingAdd(
+            materialized_bytes,
+            sizeof(std::pair<const std::string, std::vector<int64_t>>) +
+                3 * sizeof(void*));
+        materialized_bytes =
+            SaturatingAdd(materialized_bytes, key.capacity() + 1);
+        materialized_bytes = SaturatingAdd(
+            materialized_bytes,
+            SaturatingMultiply(postings.capacity(), sizeof(int64_t)));
+    }
+    return MaterializedChunk{
+        std::move(record_batch), std::move(bson_postings), materialized_bytes};
+}
+
+void
+JsonKeyStats::BuildKeyStatsParallel(
+    const std::vector<JsonStatsRowRange>& row_ranges, bool nullable) {
+    if (row_ranges.empty()) {
+        AssertInfo(num_rows_ == 0,
+                   "materialized 0 json stats rows, expected {}",
+                   num_rows_);
+        return;
+    }
+
+    AssertInfo(parquet_writer_ != nullptr,
+               "json stats parquet writer must be initialized before "
+               "materialize");
+    AssertInfo(bson_inverted_index_ != nullptr,
+               "json stats bson index must be initialized before materialize");
+    auto schema = parquet_writer_->GetSchema();
+    AssertInfo(schema != nullptr,
+               "json stats parquet writer schema must be initialized before "
+               "materialize");
+
+    auto* executor = milvus::futures::getJsonStatsBuildExecutor();
+    const auto max_active_tasks = std::min(
+        row_ranges.size(), std::max<size_t>(1, executor->numThreads()));
+    auto& memory_budget = JsonStatsBuildMemoryBudget::GetInstance();
+
+    struct ActiveMaterializeTask {
+        std::shared_ptr<std::atomic<size_t>> accounted_bytes;
+        folly::Future<MaterializedChunk> future;
+    };
+
+    std::vector<ActiveMaterializeTask> tasks;
+    tasks.reserve(row_ranges.size());
+    size_t next_submit = 0;
+    size_t next_consume = 0;
+    std::exception_ptr first_exception;
+
+    auto remember_exception = [&](std::exception_ptr exception) {
+        if (first_exception == nullptr) {
+            first_exception = std::move(exception);
+        }
+    };
+
+    auto submit_next = [&](bool block_for_budget) -> bool {
+        size_t reservation_bytes = 0;
+        JsonStatsRowRange range;
+        try {
+            range = row_ranges[next_submit];
+            reservation_bytes =
+                EstimateJsonStatsMaterializeReservationBytes(range, *schema);
+        } catch (...) {
+            remember_exception(std::current_exception());
+            return false;
+        }
+
+        std::shared_ptr<std::atomic<size_t>> accounted_bytes;
+        try {
+            accounted_bytes =
+                std::make_shared<std::atomic<size_t>>(reservation_bytes);
+            if (block_for_budget) {
+                memory_budget.Acquire(reservation_bytes);
+            } else if (!memory_budget.TryAcquire(reservation_bytes)) {
+                return false;
+            }
+        } catch (...) {
+            remember_exception(std::current_exception());
+            return false;
+        }
+
+        try {
+            auto future = folly::via(
+                executor,
+                [this,
+                 range = std::move(range),
+                 nullable,
+                 schema,
+                 reservation_bytes,
+                 accounted_bytes,
+                 &memory_budget]() {
+                    auto result =
+                        MaterializeKeyStatsRange(range, nullable, schema);
+                    memory_budget.ReconcileReservation(reservation_bytes,
+                                                       result.memory_bytes);
+                    accounted_bytes->store(result.memory_bytes,
+                                           std::memory_order_release);
+                    return result;
+                });
+            tasks.push_back(
+                ActiveMaterializeTask{accounted_bytes, std::move(future)});
+            ++next_submit;
+        } catch (...) {
+            memory_budget.Release(
+                accounted_bytes->load(std::memory_order_acquire));
+            remember_exception(std::current_exception());
+            return false;
+        }
+        return true;
+    };
+
+    auto refill = [&]() {
+        while (first_exception == nullptr && next_submit < row_ranges.size() &&
+               tasks.size() - next_consume < max_active_tasks) {
+            const bool block_for_budget = tasks.size() == next_consume;
+            if (!submit_next(block_for_budget)) {
+                break;
+            }
+        }
+    };
+
+    auto release_task_budget = [&](const ActiveMaterializeTask& task) {
+        memory_budget.Release(
+            task.accounted_bytes->load(std::memory_order_acquire));
+    };
+
+    auto drain_submitted_tasks = [&]() {
+        while (next_consume < tasks.size()) {
+            auto& task = tasks[next_consume];
+            try {
+                std::move(task.future).get();
+            } catch (...) {
+                remember_exception(std::current_exception());
+            }
+            release_task_budget(task);
+            ++next_consume;
+        }
+    };
+
+    refill();
+
+    int64_t processed_rows = 0;
+    while (next_consume < tasks.size()) {
+        auto& task = tasks[next_consume];
+        try {
+            auto result = std::move(task.future).get();
+            if (first_exception == nullptr) {
+                const auto& range = row_ranges[next_consume];
+                AssertInfo(range.global_begin == processed_rows,
+                           "json stats materialize result starts at global "
+                           "row {}, expected {}",
+                           range.global_begin,
+                           processed_rows);
+
+                auto status =
+                    parquet_writer_->AppendRecordBatch(result.record_batch);
+                if (!status.ok()) {
+                    ThrowInfo(milvus::storage::ArrowStatusToErrorCode(status),
+                              "failed to append materialized json stats record "
+                              "batch: {}",
+                              status.ToString());
+                }
+                for (auto& [key, postings] : result.bson_postings) {
+                    bson_inverted_index_->AddRecords(key, std::move(postings));
+                }
+
+                processed_rows += range.row_count;
+            }
+        } catch (...) {
+            remember_exception(std::current_exception());
+        }
+        release_task_budget(task);
+        ++next_consume;
+
+        if (first_exception != nullptr) {
+            drain_submitted_tasks();
+            break;
+        }
+
+        refill();
+    }
+
+    // Consume every submitted future before propagating an error so no worker
+    // can retain references to this JsonKeyStats or its FieldData inputs.
+    if (first_exception != nullptr) {
+        std::rethrow_exception(first_exception);
+    }
+
+    AssertInfo(processed_rows == num_rows_,
+               "materialized {} json stats rows, expected {}",
+               processed_rows,
+               num_rows_);
 }
 
 std::string
@@ -901,13 +1580,35 @@ JsonKeyStats::AddBucketName(const std::string& remote_prefix) {
 void
 JsonKeyStats::BuildWithFieldData(const std::vector<FieldDataPtr>& field_datas,
                                  bool nullable) {
-    // collect key stats info and classify key type
-    auto infos = CollectKeyInfo(field_datas, nullable);
-    LOG_INFO("collect key infos: {} for segment {} for field {}",
-             PrintKeyInfo(infos),
-             segment_id_,
-             field_id_);
-    key_types_ = ClassifyJsonKeyLayoutType(infos);
+    const auto row_ranges =
+        CreateJsonStatsRowRanges(field_datas, kJsonStatsRowsPerRange);
+    auto* executor = milvus::futures::getJsonStatsBuildExecutor();
+    const auto executor_threads = std::max<size_t>(1, executor->numThreads());
+    const auto effective_concurrency =
+        std::min(row_ranges.size(), executor_threads);
+    const bool use_parallel_pipeline = effective_concurrency > 1;
+    LOG_INFO(
+        "json stats build selects {} pipeline for segment {} field {} with "
+        "{} row ranges, {} executor threads, and effective concurrency {}",
+        use_parallel_pipeline ? "parallel" : "serial",
+        segment_id_,
+        field_id_,
+        row_ranges.size(),
+        executor_threads,
+        effective_concurrency);
+
+    {
+        // Release collected key stats after classification, before materializing
+        // rows and accumulating BSON postings.
+        auto infos = use_parallel_pipeline
+                         ? CollectKeyInfo(row_ranges, nullable)
+                         : CollectKeyInfo(field_datas, nullable);
+        LOG_INFO("collect key infos: {} for segment {} for field {}",
+                 PrintKeyInfo(infos),
+                 segment_id_,
+                 field_id_);
+        key_types_ = ClassifyJsonKeyLayoutType(infos);
+    }
     LOG_INFO("key types infos: {} for segment {} for field {}",
              PrintJsonKeyLayoutType(key_types_),
              segment_id_,
@@ -931,7 +1632,20 @@ JsonKeyStats::BuildWithFieldData(const std::vector<FieldDataPtr>& field_datas,
     auto writer_context =
         ParquetWriterFactory::CreateContext(key_types_, remote_prefix);
     parquet_writer_->Init(std::move(writer_context));
-    BuildKeyStats(field_datas, nullable);
+    if (use_parallel_pipeline) {
+        // Arrow slices retain the complete backing buffers. Keep every
+        // materialized range within the writer batch limit so
+        // AppendRecordBatch can hand it off without slicing; otherwise
+        // downstream memory accounting would charge a small slice for the
+        // full range and undersize row groups.
+        const auto materialize_rows_per_range =
+            std::min(kJsonStatsRowsPerRange, write_batch_size_);
+        const auto materialize_row_ranges =
+            CreateJsonStatsRowRanges(field_datas, materialize_rows_per_range);
+        BuildKeyStatsParallel(materialize_row_ranges, nullable);
+    } else {
+        BuildKeyStats(row_ranges, nullable);
+    }
     auto close_status = parquet_writer_->Close();
     if (!close_status.ok()) {
         ThrowInfo(milvus::storage::ArrowStatusToErrorCode(close_status),

internal/core/src/index/json_stats/JsonKeyStats.h

@@ -29,6 +29,7 @@
 #include <mutex>
 #include <optional>
 #include <set>
+#include <stdexcept>
 #include <string>
 #include <string_view>
 #include <type_traits>
@@ -71,20 +72,41 @@
 #include "storage/MemFileManagerImpl.h"
 
 class CollectSingleJsonStatsInfoAccessor;
+class CollectKeyInfoAccessor;
+class BuildKeyStatsAccessor;
 // Forward declaration of test accessor in global namespace for friend declaration
 class TraverseJsonForBuildStatsAccessor;
 class JsonStatsProjectionTestAccessor;
 class JsonStatsScanTestAccessor;
 
 namespace milvus::index {
+
+struct JsonStatsFieldDataSlice {
+    FieldDataPtr data;
+    int64_t local_begin;
+    int64_t row_count;
+};
+
+struct JsonStatsRowRange {
+    int64_t global_begin;
+    int64_t row_count;
+    std::vector<JsonStatsFieldDataSlice> slices;
+};
+
+std::vector<JsonStatsRowRange>
+CreateJsonStatsRowRanges(const std::vector<FieldDataPtr>& field_datas,
+                         int64_t max_rows_per_range);
+
 class JsonKeyStats : public ScalarIndex<std::string> {
  public:
+    static constexpr int64_t kDefaultWriteBatchSize = 81920;
+
     explicit JsonKeyStats(
         const storage::FileManagerContext& ctx,
         bool is_load,
         int64_t json_stats_max_shredding_columns = 1024,
         double json_stats_shredding_ratio_threshold = 0.3,
-        int64_t json_stats_write_batch_size = 81920,
+        int64_t json_stats_write_batch_size = kDefaultWriteBatchSize,
         uint32_t tantivy_index_version = TANTIVY_INDEX_LATEST_VERSION);
 
     ~JsonKeyStats() override;
@@ -463,9 +485,14 @@ class JsonKeyStats : public ScalarIndex<std::string> {
         return ss.str();
     }
 
+    // Keep the original serial implementation for differential tests.
     std::map<JsonKey, KeyStatsInfo>
     CollectKeyInfo(const std::vector<FieldDataPtr>& field_datas, bool nullable);
 
+    std::map<JsonKey, KeyStatsInfo>
+    CollectKeyInfo(const std::vector<JsonStatsRowRange>& row_ranges,
+                   bool nullable);
+
     void
     TraverseJsonForStats(const char* json,
                          jsmntok* tokens,
@@ -496,8 +523,30 @@ class JsonKeyStats : public ScalarIndex<std::string> {
     std::map<JsonKey, JsonKeyLayoutType>
     ClassifyJsonKeyLayoutType(const std::map<JsonKey, KeyStatsInfo>& infos);
 
+    // Keep the original serial implementation for differential tests.
     void
-    BuildKeyStats(const std::vector<FieldDataPtr>& field_datas, bool nullable);
+    BuildKeyStats(const std::vector<JsonStatsRowRange>& row_ranges,
+                  bool nullable);
+
+    void
+    BuildKeyStatsParallel(const std::vector<JsonStatsRowRange>& row_ranges,
+                          bool nullable);
+
+    static size_t
+    EstimateJsonStatsMaterializeReservationBytes(const JsonStatsRowRange& range,
+                                                 const arrow::Schema& schema);
+
+    struct MaterializedChunk {
+        std::shared_ptr<arrow::RecordBatch> record_batch;
+        std::map<std::string, std::vector<int64_t>> bson_postings;
+        size_t memory_bytes;
+    };
+
+    MaterializedChunk
+    MaterializeKeyStatsRange(
+        const JsonStatsRowRange& range,
+        bool nullable,
+        const std::shared_ptr<arrow::Schema>& schema) const;
 
     void
     BuildKeyStatsForRow(std::string_view json_str, uint32_t row_id);
@@ -524,22 +573,26 @@ class JsonKeyStats : public ScalarIndex<std::string> {
     AddKeyStats(const std::vector<std::string>& path,
                 JSONType type,
                 const std::string& value,
-                std::map<JsonKey, std::string>& values);
+                std::map<JsonKey, std::string>& values) const;
+
+    bool
+    ParseJsonForBuildStats(std::string_view json_str,
+                           std::map<JsonKey, std::string>& values) const;
 
     void
     TraverseJsonForBuildStats(const char* json,
                               jsmntok* tokens,
                               int& index,
                               std::vector<std::string>& path,
-                              std::map<JsonKey, std::string>& values);
+                              std::map<JsonKey, std::string>& values) const;
 
     bool
-    IsBoolean(const std::string& str) {
+    IsBoolean(const std::string& str) const {
         return str == "true" || str == "false";
     }
 
     bool
-    IsInt64(const std::string& str) {
+    IsInt64(const std::string& str) const {
         std::istringstream iss(str);
         int64_t num;
         iss >> num;
@@ -548,32 +601,36 @@ class JsonKeyStats : public ScalarIndex<std::string> {
     }
 
     bool
-    IsFloat(const std::string& str) {
+    IsFloat(const std::string& str) const {
         try {
             std::stof(str);
             return true;
-        } catch (...) {
+        } catch (const std::invalid_argument&) {
+            return false;
+        } catch (const std::out_of_range&) {
             return false;
         }
     }
 
     bool
-    IsDouble(const std::string& str) {
+    IsDouble(const std::string& str) const {
         try {
             std::stod(str);
             return true;
-        } catch (...) {
+        } catch (const std::invalid_argument&) {
+            return false;
+        } catch (const std::out_of_range&) {
             return false;
         }
     }
 
     bool
-    IsNull(const std::string& str) {
+    IsNull(const std::string& str) const {
         return str == "null";
     }
 
     JSONType
-    getType(const std::string& str) {
+    getType(const std::string& str) const {
         if (IsBoolean(str)) {
             return JSONType::BOOL;
             // TODO: add int8, int16, int32 support
@@ -684,6 +741,8 @@ class JsonKeyStats : public ScalarIndex<std::string> {
     // Friend accessor for unit tests to call private methods safely.
     friend class ::TraverseJsonForBuildStatsAccessor;
     friend class ::CollectSingleJsonStatsInfoAccessor;
+    friend class ::CollectKeyInfoAccessor;
+    friend class ::BuildKeyStatsAccessor;
     friend class ::JsonStatsProjectionTestAccessor;
     friend class ::JsonStatsScanTestAccessor;
 };

internal/core/src/index/json_stats/JsonStatsBuildMemoryBudget.h

@@ -0,0 +1,148 @@
+// Licensed to the LF AI & Data foundation under one
+// or more contributor license agreements. See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership. The ASF licenses this file
+// to you 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 <condition_variable>
+#include <cstddef>
+#include <limits>
+#include <mutex>
+
+#include "common/EasyAssert.h"
+
+namespace milvus::index {
+
+/// Process-wide byte budget for JSON stats ranges submitted for asynchronous
+/// materialization but not yet consumed. Capacity 0 means unlimited. An
+/// oversized range may run exclusively to guarantee progress.
+class JsonStatsBuildMemoryBudget {
+ public:
+    static JsonStatsBuildMemoryBudget&
+    GetInstance() {
+        static JsonStatsBuildMemoryBudget instance;
+        return instance;
+    }
+
+    /// Block until enough budget is available. The caller must not hold work
+    /// whose completion is needed to release budget.
+    void
+    Acquire(size_t bytes) {
+        std::unique_lock<std::mutex> lock(mu_);
+        cv_.wait(lock, [this, bytes] { return CanAcquireLocked(bytes); });
+        inflight_bytes_ += bytes;
+    }
+
+    /// Try to claim budget without blocking. Refill loops use this while they
+    /// still own inflight work.
+    bool
+    TryAcquire(size_t bytes) {
+        std::lock_guard<std::mutex> lock(mu_);
+        if (!CanAcquireLocked(bytes)) {
+            return false;
+        }
+        inflight_bytes_ += bytes;
+        return true;
+    }
+
+    void
+    Release(size_t bytes) {
+        {
+            std::lock_guard<std::mutex> lock(mu_);
+            AssertInfo(
+                bytes <= inflight_bytes_,
+                "JSON stats build memory budget over-release: release {}, "
+                "inflight {}",
+                bytes,
+                inflight_bytes_);
+            inflight_bytes_ -= bytes;
+        }
+        cv_.notify_all();
+    }
+
+    /// Replace a task's pre-dispatch reservation with its measured result
+    /// size. Growth is intentionally non-blocking: completed workers must not
+    /// wait for consumers ordered behind other active tasks. A temporary
+    /// overage prevents new acquisitions until consumers release enough bytes.
+    void
+    ReconcileReservation(size_t reserved_bytes, size_t actual_bytes) {
+        bool released_bytes = false;
+        {
+            std::lock_guard<std::mutex> lock(mu_);
+            AssertInfo(reserved_bytes <= inflight_bytes_,
+                       "JSON stats build memory budget reconcile exceeds "
+                       "inflight: "
+                       "reserved {}, inflight {}",
+                       reserved_bytes,
+                       inflight_bytes_);
+            const auto other_inflight_bytes = inflight_bytes_ - reserved_bytes;
+            AssertInfo(actual_bytes <= std::numeric_limits<size_t>::max() -
+                                           other_inflight_bytes,
+                       "JSON stats build memory budget reconcile overflow: "
+                       "actual "
+                       "{}, other inflight {}",
+                       actual_bytes,
+                       other_inflight_bytes);
+            inflight_bytes_ = other_inflight_bytes + actual_bytes;
+            released_bytes = actual_bytes < reserved_bytes;
+        }
+        if (released_bytes) {
+            cv_.notify_all();
+        }
+    }
+
+    size_t
+    CapacityBytes() const {
+        std::lock_guard<std::mutex> lock(mu_);
+        return capacity_bytes_;
+    }
+
+    size_t
+    InflightBytes() const {
+        std::lock_guard<std::mutex> lock(mu_);
+        return inflight_bytes_;
+    }
+
+    void
+    SetCapacityBytes(size_t bytes) {
+        {
+            std::lock_guard<std::mutex> lock(mu_);
+            capacity_bytes_ = bytes;
+        }
+        cv_.notify_all();
+    }
+
+ private:
+    JsonStatsBuildMemoryBudget() = default;
+
+    bool
+    CanAcquireLocked(size_t bytes) const {
+        if (capacity_bytes_ == 0) {
+            return true;
+        }
+        if (bytes > capacity_bytes_) {
+            return inflight_bytes_ == 0;
+        }
+        return inflight_bytes_ <= capacity_bytes_ &&
+               bytes <= capacity_bytes_ - inflight_bytes_;
+    }
+
+    mutable std::mutex mu_;
+    std::condition_variable cv_;
+    size_t inflight_bytes_{0};
+    size_t capacity_bytes_{0};
+};
+
+}  // namespace milvus::index

internal/core/src/index/json_stats/bson_inverted.cpp

@@ -76,6 +76,25 @@ BsonInvertedIndex::AddRecord(const std::string& key,
         EncodeInvertedIndexValue(row_id, offset));
 }
 
+void
+BsonInvertedIndex::AddRecords(const std::string& key,
+                              std::vector<int64_t> records) {
+    if (records.empty()) {
+        return;
+    }
+
+    auto& destination = inverted_index_map_[key];
+    if (destination.empty()) {
+        destination = std::move(records);
+        return;
+    }
+
+    // Let vector retain spare capacity from its geometric growth. Reserving
+    // exactly the required size for every chunk would reallocate and copy the
+    // entire accumulated postings list on nearly every merge.
+    destination.insert(destination.end(), records.begin(), records.end());
+}
+
 void
 BsonInvertedIndex::BuildIndex() {
     if (wrapper_ == nullptr) {

internal/core/src/index/json_stats/bson_inverted.h

@@ -54,6 +54,9 @@ class BsonInvertedIndex {
     void
     AddRecord(const std::string& key, uint32_t row_id, uint32_t offset);
 
+    void
+    AddRecords(const std::string& key, std::vector<int64_t> records);
+
     void
     BuildIndex();
 

internal/core/src/index/json_stats/parquet_writer.cpp

@@ -18,7 +18,9 @@
 
 #include <arrow/array/builder_binary.h>
 #include <arrow/array/builder_primitive.h>
+#include <algorithm>
 #include <exception>
+#include <new>
 #include <utility>
 
 #include "arrow/array/builder_base.h"
@@ -194,7 +196,7 @@ JsonStatsParquetWriter::AppendValue(const std::string& key,
     }
 
     auto& builder = it->second;
-    auto ast = AppendDataToBuilder(value, builder);
+    auto ast = AppendJsonStatsValueToBuilder(value, builder);
     if (!ast.ok()) {
         ThrowInfo(milvus::storage::ArrowStatusToErrorCode(ast),
                   "failed to append data to builder");
@@ -213,7 +215,7 @@ JsonStatsParquetWriter::AppendRow(
         }
 
         auto& builder = it->second;
-        auto status = AppendDataToBuilder(value, builder);
+        auto status = AppendJsonStatsValueToBuilder(value, builder);
         if (!status.ok()) {
             ThrowInfo(milvus::storage::ArrowStatusToErrorCode(status),
                       "failed to append data to builder");
@@ -224,7 +226,73 @@ JsonStatsParquetWriter::AppendRow(
 }
 
 arrow::Status
-JsonStatsParquetWriter::AppendDataToBuilder(
+JsonStatsParquetWriter::AppendRecordBatch(
+    const std::shared_ptr<arrow::RecordBatch>& batch) {
+    if (batch == nullptr) {
+        return arrow::Status::Invalid(
+            "cannot append a null json stats record batch");
+    }
+    if (schema_ == nullptr || packed_writer_ == nullptr) {
+        return arrow::Status::Invalid(
+            "json stats parquet writer is not initialized");
+    }
+    if (schema_->num_fields() != batch->num_columns()) {
+        return arrow::Status::Invalid(
+            "json stats record batch column count does not match writer "
+            "schema");
+    }
+    if (!schema_->Equals(*batch->schema(), true)) {
+        return arrow::Status::Invalid(
+            "json stats record batch schema does not match writer schema");
+    }
+    auto validate_status = batch->Validate();
+    if (!validate_status.ok()) {
+        return validate_status;
+    }
+
+    if (batch->num_rows() == 0) {
+        return arrow::Status::OK();
+    }
+
+    // Preserve row order if a caller switches from the row-oriented API to
+    // pre-materialized record batches. The parallel JSON-stats path does not
+    // normally have pending builder rows.
+    if (unflushed_row_count_ > 0) {
+        auto result = WriteCurrentBatch();
+        if (!result.ok()) {
+            return result.status();
+        }
+    }
+
+    // MaterializeKeyStatsRange already produced complete Arrow arrays. Pass
+    // them straight through so the writer does not copy every value into a
+    // second set of builders merely to finish those builders back into arrays.
+    // Keep batch_size_ as an upper bound for a single write; Slice shares the
+    // original buffers and therefore remains zero-copy.
+    const auto max_batch_rows = static_cast<int64_t>(batch_size_);
+    int64_t offset = 0;
+    while (offset < batch->num_rows()) {
+        const auto rows_to_write =
+            std::min(max_batch_rows, batch->num_rows() - offset);
+        auto slice = offset == 0 && rows_to_write == batch->num_rows()
+                         ? batch
+                         : batch->Slice(offset, rows_to_write);
+        auto status = packed_writer_->Write(slice);
+        if (!status.ok()) {
+            return status;
+        }
+        offset += rows_to_write;
+    }
+
+    // Account for the original arrays once. Multiple zero-copy slices share
+    // these buffers, so accounting each slice would overstate their size.
+    UpdatePathSizeMap(batch->columns());
+    all_row_count_ += static_cast<size_t>(batch->num_rows());
+    return arrow::Status::OK();
+}
+
+arrow::Status
+AppendJsonStatsValueToBuilder(
     const std::string& value,
     const std::shared_ptr<arrow::ArrayBuilder>& builder) {
     auto type_id = builder->type()->id();
@@ -296,6 +364,10 @@ JsonStatsParquetWriter::AppendDataToBuilder(
                           type_id,
                           value);
         }
+    } catch (const std::bad_alloc&) {
+        throw;
+    } catch (const SegcoreError&) {
+        throw;
     } catch (const std::exception& e) {
         ThrowInfo(ErrorCode::UnexpectedError,
                   "failed to append data to builder: {}",

internal/core/src/index/json_stats/parquet_writer.h

@@ -101,6 +101,11 @@ struct TableStatsInfo {
     std::map<JsonKey, JsonKeyLayoutType> column_map;
 };
 
+arrow::Status
+AppendJsonStatsValueToBuilder(
+    const std::string& value,
+    const std::shared_ptr<arrow::ArrayBuilder>& builder);
+
 class ColumnGroupingStrategy {
  public:
     virtual ~ColumnGroupingStrategy() = default;
@@ -198,6 +203,9 @@ class JsonStatsParquetWriter {
     void
     AppendSharedRow(const uint8_t* data, size_t length);
 
+    arrow::Status
+    AppendRecordBatch(const std::shared_ptr<arrow::RecordBatch>& batch);
+
     arrow::Status
     Flush();
 
@@ -220,14 +228,15 @@ class JsonStatsParquetWriter {
         return total_size_;
     }
 
+    const std::shared_ptr<arrow::Schema>&
+    GetSchema() const {
+        return schema_;
+    }
+
     void
     UpdatePathSizeMap(const std::vector<std::shared_ptr<arrow::Array>>& arrays);
 
  private:
-    arrow::Status
-    AppendDataToBuilder(const std::string& value,
-                        const std::shared_ptr<arrow::ArrayBuilder>& builder);
-
     // init info
     std::shared_ptr<arrow::Schema> schema_{nullptr};
 

internal/core/src/index/json_stats/utils.cpp

@@ -151,7 +151,8 @@ CreateArrowBuilders(const std::map<JsonKey, JsonKeyLayoutType>& column_map) {
     for (const auto& [key, type] : column_map) {
         switch (type) {
             case JsonKeyLayoutType::SHARED:
-                builders_map[key.ToColumnName()] = shared_builder;
+                // Shared paths are appended together through the final BSON
+                // builder, never looked up as independent Arrow columns.
                 break;
             case JsonKeyLayoutType::TYPED:
             case JsonKeyLayoutType::TYPED_NOT_ALL:
@@ -172,6 +173,21 @@ CreateArrowBuilders(const std::map<JsonKey, JsonKeyLayoutType>& column_map) {
     return {std::move(builders), std::move(builders_map)};
 }
 
+std::pair<std::vector<std::shared_ptr<arrow::ArrayBuilder>>,
+          std::map<std::string, std::shared_ptr<arrow::ArrayBuilder>>>
+CreateArrowBuildersForColumns(const std::set<JsonKey>& column_keys) {
+    std::vector<std::shared_ptr<arrow::ArrayBuilder>> builders;
+    builders.reserve(column_keys.size() + 1);
+    std::map<std::string, std::shared_ptr<arrow::ArrayBuilder>> builders_map;
+    for (const auto& key : column_keys) {
+        auto builder = CreateArrowBuilder(key.type_);
+        builders_map[key.ToColumnName()] = builder;
+        builders.push_back(std::move(builder));
+    }
+    builders.push_back(CreateSharedArrowBuilder());
+    return {std::move(builders), std::move(builders_map)};
+}
+
 std::shared_ptr<arrow::Schema>
 CreateArrowSchema(const std::map<JsonKey, JsonKeyLayoutType>& column_map) {
     std::vector<std::shared_ptr<arrow::Field>> fields;
@@ -315,4 +331,4 @@ JsonStatsMeta::DeserializeToKeyFieldMap(const std::string& json_str) {
     return key_field_map;
 }
 
-}  // namespace milvus::index
+}  // namespace milvus::index

internal/core/src/index/json_stats/utils.h

@@ -19,6 +19,7 @@
 #include <cstring>
 #include "common/FastMem.h"
 #include <map>
+#include <new>
 #include <optional>
 #include <set>
 #include <string>
@@ -83,6 +84,8 @@ UnescapeJsonString(const std::string& escaped) {
                       escaped);
         }
         return std::string(std::string_view(elem.get_string()));
+    } catch (const std::bad_alloc&) {
+        throw;
     } catch (const SegcoreError&) {
         // Already classified above (DataFormatBroken); SegcoreError derives from
         // std::runtime_error, so without this the generic handler below would
@@ -398,6 +401,12 @@ std::pair<std::vector<std::shared_ptr<arrow::ArrayBuilder>>,
           std::map<std::string, std::shared_ptr<arrow::ArrayBuilder>>>
 CreateArrowBuilders(const std::map<JsonKey, JsonKeyLayoutType>& column_map);
 
+// Build task-local Arrow columns without visiting the potentially much larger
+// set of keys stored in the shared BSON column. The shared builder is last.
+std::pair<std::vector<std::shared_ptr<arrow::ArrayBuilder>>,
+          std::map<std::string, std::shared_ptr<arrow::ArrayBuilder>>>
+CreateArrowBuildersForColumns(const std::set<JsonKey>& column_keys);
+
 std::shared_ptr<arrow::Schema>
 CreateArrowSchema(const std::map<JsonKey, JsonKeyLayoutType>& column_map);
 

internal/core/unittest/test_json_stats/test_parquet_writer.cpp

@@ -1,8 +1,10 @@
 #include <arrow/type.h>
+#include <gmock/gmock.h>
 #include <gtest/gtest.h>
 #include <filesystem>
 #include <map>
 #include <memory>
+#include <new>
 #include <set>
 #include <stdexcept>
 #include <string>
@@ -13,9 +15,73 @@
 #include "index/json_stats/parquet_writer.h"
 #include "index/json_stats/utils.h"
 #include "segcore/default_fs.h"
+#include "storage/StatusToErrorCode.h"
 #include "test_utils/Constants.h"
 
 namespace milvus::index {
+namespace {
+
+class MockMemoryPool : public arrow::ProxyMemoryPool {
+ public:
+    MockMemoryPool() : arrow::ProxyMemoryPool(arrow::default_memory_pool()) {
+    }
+
+    using arrow::ProxyMemoryPool::Allocate;
+    MOCK_METHOD(arrow::Status,
+                Allocate,
+                (int64_t, int64_t, uint8_t**),
+                (override));
+};
+
+}  // namespace
+
+TEST(JsonStatsArrowBuilderTest, PreservesBadAlloc) {
+    MockMemoryPool pool;
+    auto builder = std::make_shared<arrow::StringBuilder>(&pool);
+    EXPECT_CALL(pool, Allocate).WillOnce(testing::Throw(std::bad_alloc{}));
+
+    EXPECT_THROW(AppendJsonStatsValueToBuilder("value", builder),
+                 std::bad_alloc);
+}
+
+TEST(JsonStatsArrowBuilderTest, PreservesTypedError) {
+    MockMemoryPool pool;
+    auto builder = std::make_shared<arrow::StringBuilder>(&pool);
+    EXPECT_CALL(pool, Allocate)
+        .WillOnce(testing::Throw(
+            SegcoreError(MemAllocateFailed, "injected allocation failure")));
+
+    try {
+        AppendJsonStatsValueToBuilder("value", builder);
+        FAIL() << "expected an allocation failure";
+    } catch (const SegcoreError& error) {
+        EXPECT_EQ(error.get_error_code(), MemAllocateFailed);
+        EXPECT_STREQ(error.what(), "injected allocation failure");
+    }
+}
+
+TEST(JsonStatsArrowBuilderTest, PreservesArrowOutOfMemory) {
+    MockMemoryPool pool;
+    auto builder = std::make_shared<arrow::StringBuilder>(&pool);
+    EXPECT_CALL(pool, Allocate)
+        .WillOnce(testing::Return(
+            arrow::Status::OutOfMemory("injected allocation failure")));
+
+    auto status = AppendJsonStatsValueToBuilder("value", builder);
+    EXPECT_TRUE(status.IsOutOfMemory());
+    EXPECT_EQ(storage::ArrowStatusToErrorCode(status), MemAllocateFailed);
+}
+
+TEST(JsonStatsArrowBuilderTest, PreservesUnsupportedType) {
+    auto builder = std::make_shared<arrow::Date32Builder>();
+    try {
+        AppendJsonStatsValueToBuilder("1", builder);
+        FAIL() << "expected an unsupported type error";
+    } catch (const SegcoreError& error) {
+        EXPECT_EQ(error.get_error_code(), Unsupported);
+    }
+}
+
 class ParquetWriterFactoryTest : public ::testing::Test {
  protected:
     void
@@ -62,7 +128,7 @@ TEST_F(ParquetWriterFactoryTest, CreateContextBasicTest) {
     EXPECT_FALSE(context.builders.empty());
     EXPECT_FALSE(context.builders_map.empty());
     EXPECT_EQ(context.builders.size(), column_map_.size());
-    EXPECT_EQ(context.builders_map.size(), column_map_.size());
+    EXPECT_EQ(context.builders_map.size(), column_map_.size() - 1);
 
     // Verify metadata
     EXPECT_TRUE(context.kv_metadata.empty());
@@ -89,7 +155,7 @@ TEST_F(ParquetWriterFactoryTest, CreateContextWithSharedFields) {
     EXPECT_NE(context.schema, nullptr);
     EXPECT_EQ(context.schema->num_fields(), 2);
 
-    EXPECT_EQ(context.builders_map.size(), 3);
+    EXPECT_EQ(context.builders_map.size(), 1);
 }
 
 TEST_F(ParquetWriterFactoryTest, CreateContextWithColumnGroups) {
@@ -142,4 +208,63 @@ TEST_F(ParquetWriterFactoryTest, CloseReturnsStatusAndIsIdempotent) {
     std::filesystem::remove_all(path_prefix);
 }
 
+TEST_F(ParquetWriterFactoryTest,
+       AppendRecordBatchDoesNotRematerializeIntoWriterBuilders) {
+    auto fs = milvus::segcore::GetDefaultArrowFileSystem();
+    auto path_prefix = std::filesystem::path(TestLocalPath) /
+                       "json_stats_writer_direct_record_batch";
+    std::filesystem::remove_all(path_prefix);
+    ASSERT_TRUE(std::filesystem::create_directories(path_prefix));
+
+    std::map<JsonKey, JsonKeyLayoutType> column_map = {
+        {JsonKey("/int", JSONType::INT64), JsonKeyLayoutType::TYPED},
+        {JsonKey("/shared", JSONType::STRING), JsonKeyLayoutType::SHARED},
+    };
+    auto context =
+        ParquetWriterFactory::CreateContext(column_map, path_prefix.string());
+    auto schema = context.schema;
+    auto writer_builders = context.builders;
+
+    milvus_storage::StorageConfig storage_config;
+    JsonStatsParquetWriter writer(fs, storage_config, 16 * 1024 * 1024, 1024);
+    writer.Init(std::move(context));
+
+    writer.AppendValue(JsonKey("/int", JSONType::INT64).ToColumnName(), "5");
+    writer.AppendSharedRow(nullptr, 0);
+    writer.AddCurrentRow();
+    for (const auto& builder : writer_builders) {
+        ASSERT_EQ(builder->length(), 1);
+    }
+
+    auto input_builders = CreateArrowBuilders(column_map).first;
+    auto int_builder =
+        std::static_pointer_cast<arrow::Int64Builder>(input_builders.front());
+    auto shared_builder =
+        std::static_pointer_cast<arrow::BinaryBuilder>(input_builders.back());
+    for (int64_t value : {int64_t{10}, int64_t{20}, int64_t{30}}) {
+        ASSERT_TRUE(int_builder->Append(value).ok());
+        ASSERT_TRUE(shared_builder->AppendNull().ok());
+    }
+
+    std::vector<std::shared_ptr<arrow::Array>> arrays;
+    arrays.reserve(input_builders.size());
+    for (auto& builder : input_builders) {
+        std::shared_ptr<arrow::Array> array;
+        ASSERT_TRUE(builder->Finish(&array).ok());
+        arrays.push_back(std::move(array));
+    }
+    auto batch = arrow::RecordBatch::Make(schema, 3, std::move(arrays));
+
+    auto status = writer.AppendRecordBatch(batch);
+    ASSERT_TRUE(status.ok()) << status.ToString();
+    for (const auto& builder : writer_builders) {
+        EXPECT_EQ(builder->length(), 0);
+    }
+    EXPECT_FALSE(writer.GetPathsToSize().empty());
+
+    status = writer.Close();
+    ASSERT_TRUE(status.ok()) << status.ToString();
+    std::filesystem::remove_all(path_prefix);
+}
+
 }  // namespace milvus::index

internal/core/unittest/test_json_stats/test_traverse_json_for_build_stats.cpp

@@ -8,10 +8,14 @@
 // 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 <cstddef>
+#include <cstdint>
 #include <cstring>
 #include <map>
+#include <memory>
 #include <string>
 #include <string_view>
+#include <tuple>
 #include <utility>
 #include <vector>
 
@@ -19,6 +23,8 @@
 #include "common/Json.h"
 #include "common/jsmn.h"
 #include "common/protobuf_utils.h"
+#include "futures/Executor.h"
+#include "futures/future_c.h"
 #include "gtest/gtest.h"
 #include "index/json_stats/JsonKeyStats.h"
 #include "index/json_stats/utils.h"
@@ -57,6 +63,25 @@ class CollectSingleJsonStatsInfoAccessor {
     }
 };
 
+// Friend accessor declared in JsonKeyStats to invoke private method for UT
+class CollectKeyInfoAccessor {
+ public:
+    static std::map<JsonKey, milvus::index::KeyStatsInfo>
+    CallLegacy(JsonKeyStats& stats,
+               const std::vector<milvus::FieldDataPtr>& field_datas,
+               bool nullable) {
+        return stats.CollectKeyInfo(field_datas, nullable);
+    }
+
+    static std::map<JsonKey, milvus::index::KeyStatsInfo>
+    CallParallel(
+        JsonKeyStats& stats,
+        const std::vector<milvus::index::JsonStatsRowRange>& row_ranges,
+        bool nullable) {
+        return stats.CollectKeyInfo(row_ranges, nullable);
+    }
+};
+
 namespace {
 
 // Helper to tokenize JSON using jsmn
@@ -81,8 +106,523 @@ Tokenize(const char* json) {
     return tokens;
 }
 
+milvus::FieldDataPtr
+CreateJsonFieldData(int64_t row_count) {
+    auto field_data = milvus::storage::CreateFieldData(
+        milvus::DataType::JSON, milvus::DataType::NONE, false);
+    if (row_count == 0) {
+        return field_data;
+    }
+
+    std::vector<milvus::Json> rows;
+    rows.reserve(row_count);
+    const std::string json = R"({"value":1})";
+    for (int64_t i = 0; i < row_count; ++i) {
+        rows.emplace_back(simdjson::padded_string(json));
+    }
+    field_data->FillFieldData(rows.data(), rows.size());
+    return field_data;
+}
+
+milvus::FieldDataPtr
+CreateJsonFieldData(const std::vector<std::string>& json_rows) {
+    auto field_data = milvus::storage::CreateFieldData(
+        milvus::DataType::JSON, milvus::DataType::NONE, false);
+    if (json_rows.empty()) {
+        return field_data;
+    }
+
+    std::vector<milvus::Json> rows;
+    rows.reserve(json_rows.size());
+    for (const auto& json : json_rows) {
+        rows.emplace_back(simdjson::padded_string(json));
+    }
+    field_data->FillFieldData(rows.data(), rows.size());
+    return field_data;
+}
+
+milvus::FieldDataPtr
+CreateNullableJsonFieldData(const std::vector<std::string>& json_rows,
+                            const std::vector<bool>& valid_rows) {
+    if (json_rows.size() != valid_rows.size()) {
+        ADD_FAILURE() << "json rows and validity rows must have the same size";
+        return nullptr;
+    }
+
+    auto field_data = milvus::storage::CreateFieldData(
+        milvus::DataType::JSON, milvus::DataType::NONE, true);
+    if (json_rows.empty()) {
+        return field_data;
+    }
+
+    std::vector<milvus::Json> rows;
+    rows.reserve(json_rows.size());
+    for (const auto& json : json_rows) {
+        rows.emplace_back(simdjson::padded_string(json));
+    }
+
+    std::vector<uint8_t> valid_bitmap((valid_rows.size() + 7) / 8, 0);
+    for (size_t i = 0; i < valid_rows.size(); ++i) {
+        if (valid_rows[i]) {
+            valid_bitmap[i / 8] |= static_cast<uint8_t>(1U << (i % 8));
+        }
+    }
+    field_data->FillFieldData(rows.data(), valid_bitmap.data(), rows.size(), 0);
+    return field_data;
+}
+
+std::unique_ptr<JsonKeyStats>
+CreateJsonKeyStatsForCollectTest() {
+    milvus::storage::FieldDataMeta field_meta{1, 2, 3, 100, {}};
+    milvus::storage::IndexMeta index_meta{3, 100, 1, 1};
+    milvus::storage::StorageConfig storage_config;
+    storage_config.storage_type = "local";
+    storage_config.root_path = TestLocalPath;
+    auto cm = milvus::storage::CreateChunkManager(storage_config);
+    auto fs = milvus::storage::InitArrowFileSystem(storage_config);
+    milvus::storage::FileManagerContext ctx(field_meta, index_meta, cm, fs);
+    return std::make_unique<JsonKeyStats>(ctx, true);
+}
+
+void
+ExpectKeyInfoMapsEqual(
+    const std::map<JsonKey, milvus::index::KeyStatsInfo>& expected,
+    const std::map<JsonKey, milvus::index::KeyStatsInfo>& actual) {
+    ASSERT_EQ(actual.size(), expected.size());
+    for (const auto& [key, expected_info] : expected) {
+        auto actual_it = actual.find(key);
+        ASSERT_NE(actual_it, actual.end()) << "missing key " << key.ToString();
+        EXPECT_EQ(actual_it->second.hit_row_num_, expected_info.hit_row_num_)
+            << key.ToString();
+        EXPECT_EQ(std::memcmp(actual_it->second.min_value_,
+                              expected_info.min_value_,
+                              sizeof(expected_info.min_value_)),
+                  0)
+            << key.ToString();
+        EXPECT_EQ(std::memcmp(actual_it->second.max_value_,
+                              expected_info.max_value_,
+                              sizeof(expected_info.max_value_)),
+                  0)
+            << key.ToString();
+    }
+}
+
+void
+ExpectHitCount(const std::map<JsonKey, milvus::index::KeyStatsInfo>& infos,
+               const JsonKey& key,
+               int32_t expected_hit_count) {
+    auto it = infos.find(key);
+    ASSERT_NE(it, infos.end()) << "missing key " << key.ToString();
+    EXPECT_EQ(it->second.hit_row_num_, expected_hit_count) << key.ToString();
+}
+
+std::map<JsonKey, milvus::index::KeyStatsInfo>
+ExpectParallelCollectMatchesLegacy(
+    const std::vector<milvus::FieldDataPtr>& field_datas,
+    bool nullable,
+    const std::vector<int64_t>& rows_per_range_values,
+    const std::vector<int>& worker_counts) {
+    int64_t expected_row_count = 0;
+    for (const auto& data : field_datas) {
+        expected_row_count += data->get_num_rows();
+    }
+
+    auto stats = CreateJsonKeyStatsForCollectTest();
+    auto legacy_infos =
+        CollectKeyInfoAccessor::CallLegacy(*stats, field_datas, nullable);
+    EXPECT_EQ(stats->Count(), expected_row_count);
+
+    for (auto rows_per_range : rows_per_range_values) {
+        auto ranges = milvus::index::CreateJsonStatsRowRanges(field_datas,
+                                                              rows_per_range);
+        for (auto worker_count : worker_counts) {
+            SCOPED_TRACE(::testing::Message()
+                         << "rows_per_range=" << rows_per_range
+                         << ", worker_count=" << worker_count
+                         << ", nullable=" << nullable);
+            executor_set_json_stats_build_thread_num(worker_count);
+            auto parallel_infos =
+                CollectKeyInfoAccessor::CallParallel(*stats, ranges, nullable);
+            EXPECT_EQ(stats->Count(), expected_row_count);
+            ExpectKeyInfoMapsEqual(legacy_infos, parallel_infos);
+        }
+    }
+    return legacy_infos;
+}
+
 }  // namespace
 
+class JsonStatsCollectKeyInfoTest : public ::testing::Test {
+ protected:
+    void
+    SetUp() override {
+        original_thread_num_ =
+            milvus::futures::getJsonStatsBuildExecutor()->numThreads();
+    }
+
+    void
+    TearDown() override {
+        executor_set_json_stats_build_thread_num(
+            static_cast<int>(original_thread_num_));
+    }
+
+    size_t original_thread_num_;
+};
+
+TEST(JsonStatsRowRangeTest, CoalescesAcrossFieldDataBoundaries) {
+    auto first = CreateJsonFieldData(2);
+    auto second = CreateJsonFieldData(5);
+    auto third = CreateJsonFieldData(1);
+
+    auto ranges =
+        milvus::index::CreateJsonStatsRowRanges({first, second, third}, 3);
+
+    ASSERT_EQ(ranges.size(), 3);
+
+    EXPECT_EQ(ranges[0].global_begin, 0);
+    EXPECT_EQ(ranges[0].row_count, 3);
+    ASSERT_EQ(ranges[0].slices.size(), 2);
+    EXPECT_EQ(ranges[0].slices[0].data.get(), first.get());
+    EXPECT_EQ(ranges[0].slices[0].local_begin, 0);
+    EXPECT_EQ(ranges[0].slices[0].row_count, 2);
+    EXPECT_EQ(ranges[0].slices[1].data.get(), second.get());
+    EXPECT_EQ(ranges[0].slices[1].local_begin, 0);
+    EXPECT_EQ(ranges[0].slices[1].row_count, 1);
+
+    EXPECT_EQ(ranges[1].global_begin, 3);
+    EXPECT_EQ(ranges[1].row_count, 3);
+    ASSERT_EQ(ranges[1].slices.size(), 1);
+    EXPECT_EQ(ranges[1].slices[0].data.get(), second.get());
+    EXPECT_EQ(ranges[1].slices[0].local_begin, 1);
+    EXPECT_EQ(ranges[1].slices[0].row_count, 3);
+
+    EXPECT_EQ(ranges[2].global_begin, 6);
+    EXPECT_EQ(ranges[2].row_count, 2);
+    ASSERT_EQ(ranges[2].slices.size(), 2);
+    EXPECT_EQ(ranges[2].slices[0].data.get(), second.get());
+    EXPECT_EQ(ranges[2].slices[0].local_begin, 4);
+    EXPECT_EQ(ranges[2].slices[0].row_count, 1);
+    EXPECT_EQ(ranges[2].slices[1].data.get(), third.get());
+    EXPECT_EQ(ranges[2].slices[1].local_begin, 0);
+    EXPECT_EQ(ranges[2].slices[1].row_count, 1);
+}
+
+TEST(JsonStatsRowRangeTest, MatchesLegacyTraversalForBoundarySizes) {
+    std::vector<milvus::FieldDataPtr> field_datas = {
+        CreateJsonFieldData(0),
+        CreateJsonFieldData(2),
+        CreateJsonFieldData(0),
+        CreateJsonFieldData(5),
+        CreateJsonFieldData(1),
+        CreateJsonFieldData(0),
+    };
+
+    using RowPosition =
+        std::tuple<const milvus::FieldDataBase*, int64_t, int64_t>;
+    std::vector<RowPosition> legacy_rows;
+    int64_t global_row = 0;
+    for (const auto& data : field_datas) {
+        for (int64_t local_row = 0; local_row < data->get_num_rows();
+             ++local_row) {
+            legacy_rows.emplace_back(data.get(), local_row, global_row++);
+        }
+    }
+
+    for (int64_t max_rows_per_range : {1, 2, 3, 4, 8, 16}) {
+        auto ranges = milvus::index::CreateJsonStatsRowRanges(
+            field_datas, max_rows_per_range);
+        std::vector<RowPosition> ranged_rows;
+        int64_t expected_global_begin = 0;
+
+        for (const auto& range : ranges) {
+            EXPECT_EQ(range.global_begin, expected_global_begin);
+            EXPECT_GT(range.row_count, 0);
+            EXPECT_LE(range.row_count, max_rows_per_range);
+
+            int64_t rows_in_range = 0;
+            for (const auto& slice : range.slices) {
+                const auto slice_global_begin =
+                    range.global_begin + rows_in_range;
+                for (int64_t offset = 0; offset < slice.row_count; ++offset) {
+                    ranged_rows.emplace_back(slice.data.get(),
+                                             slice.local_begin + offset,
+                                             slice_global_begin + offset);
+                }
+                rows_in_range += slice.row_count;
+            }
+            EXPECT_EQ(rows_in_range, range.row_count);
+            expected_global_begin += range.row_count;
+        }
+
+        EXPECT_EQ(ranged_rows, legacy_rows);
+    }
+}
+
+TEST(JsonStatsRowRangeTest, HandlesEmptyInputAndRejectsZeroRangeSize) {
+    EXPECT_TRUE(milvus::index::CreateJsonStatsRowRanges({}, 4).empty());
+    EXPECT_TRUE(
+        milvus::index::CreateJsonStatsRowRanges({CreateJsonFieldData(0)}, 4)
+            .empty());
+    EXPECT_ANY_THROW(
+        milvus::index::CreateJsonStatsRowRanges({CreateJsonFieldData(1)}, 0));
+}
+
+TEST_F(JsonStatsCollectKeyInfoTest,
+       ParallelMatchesLegacyAcrossFieldDataBoundaries) {
+    auto first = CreateJsonFieldData(std::vector<std::string>{
+        R"({"a":1,"b":"x","nested":{"flag":true}})",
+        R"({"a":2,"b":"y"})",
+        R"({"a":"mixed","items":[1,2]})",
+    });
+    auto second = CreateJsonFieldData(std::vector<std::string>{
+        R"({})",
+        R"({"nested":{"flag":false},"null_value":null})",
+        R"({"a":3,"b":"z"})",
+        R"([])",
+        "",
+    });
+    std::vector<milvus::FieldDataPtr> field_datas = {first, second};
+    auto ranges = milvus::index::CreateJsonStatsRowRanges(field_datas, 2);
+    ASSERT_EQ(ranges.size(), 4);
+    ASSERT_EQ(ranges[1].slices.size(), 2);
+
+    auto stats = CreateJsonKeyStatsForCollectTest();
+    auto legacy_infos =
+        CollectKeyInfoAccessor::CallLegacy(*stats, field_datas, false);
+    EXPECT_EQ(stats->Count(), 8);
+
+    executor_set_json_stats_build_thread_num(1);
+    auto single_worker_infos =
+        CollectKeyInfoAccessor::CallParallel(*stats, ranges, false);
+    EXPECT_EQ(stats->Count(), 8);
+    ExpectKeyInfoMapsEqual(legacy_infos, single_worker_infos);
+
+    executor_set_json_stats_build_thread_num(4);
+    auto parallel_infos =
+        CollectKeyInfoAccessor::CallParallel(*stats, ranges, false);
+    EXPECT_EQ(stats->Count(), 8);
+    ExpectKeyInfoMapsEqual(legacy_infos, parallel_infos);
+
+    ExpectHitCount(parallel_infos, JsonKey{"/a", JSONType::INT64}, 3);
+    ExpectHitCount(parallel_infos, JsonKey{"/a", JSONType::STRING}, 1);
+    ExpectHitCount(parallel_infos, JsonKey{"/nested", JSONType::OBJECT}, 2);
+    ExpectHitCount(parallel_infos, JsonKey{"/nested/flag", JSONType::BOOL}, 2);
+    ExpectHitCount(parallel_infos, JsonKey{"/null_value", JSONType::NONE}, 1);
+    ExpectHitCount(parallel_infos, JsonKey{"", JSONType::ARRAY}, 1);
+}
+
+TEST_F(JsonStatsCollectKeyInfoTest,
+       ParallelPreservesNonNulTerminatedJsonViewLength) {
+    const std::string json = R"({"a":1,"b":"x"})";
+    std::string buffer = json;
+    buffer.append(simdjson::SIMDJSON_PADDING, '\xAB');
+
+    auto field_data = std::dynamic_pointer_cast<milvus::FieldDataJsonImpl>(
+        milvus::storage::CreateFieldData(
+            milvus::DataType::JSON, milvus::DataType::NONE, false));
+    ASSERT_NE(field_data, nullptr);
+    field_data->add_json_data({milvus::Json(buffer.data(), json.size())});
+
+    auto ranges = milvus::index::CreateJsonStatsRowRanges({field_data}, 1);
+    auto stats = CreateJsonKeyStatsForCollectTest();
+    executor_set_json_stats_build_thread_num(2);
+    auto infos = CollectKeyInfoAccessor::CallParallel(*stats, ranges, false);
+
+    EXPECT_EQ(stats->Count(), 1);
+    ExpectHitCount(infos, JsonKey{"/a", JSONType::INT64}, 1);
+    ExpectHitCount(infos, JsonKey{"/b", JSONType::STRING}, 1);
+}
+
+TEST_F(JsonStatsCollectKeyInfoTest, ParallelMatchesLegacyForEmptyInputs) {
+    auto empty_infos =
+        ExpectParallelCollectMatchesLegacy({}, false, {1, 16 * 1024}, {1, 4});
+    EXPECT_TRUE(empty_infos.empty());
+
+    std::vector<milvus::FieldDataPtr> empty_field_datas = {
+        CreateJsonFieldData(0),
+        CreateJsonFieldData(0),
+        CreateJsonFieldData(0),
+    };
+    auto empty_field_data_infos = ExpectParallelCollectMatchesLegacy(
+        empty_field_datas, false, {1, 2, 16 * 1024}, {1, 4});
+    EXPECT_TRUE(empty_field_data_infos.empty());
+}
+
+TEST_F(JsonStatsCollectKeyInfoTest,
+       ParallelMatchesLegacyForAllJsonTypesAndDeepPaths) {
+    auto first = CreateJsonFieldData(std::vector<std::string>{
+        "42",
+        "-42",
+        "0",
+        "1.5",
+        "6.02e23",
+        "true",
+        "false",
+        "null",
+        "\"root string\"",
+        "[]",
+        R"([1,{"array_child":"is_not_traversed"}])",
+        "{}",
+    });
+    auto second = CreateJsonFieldData(std::vector<std::string>{
+        R"({"l1":{"l2":{"l3":{"int":1,"double":2.5,"bool":true,"null":null,"string":"x","array":[1,{"ignored":2}]}}},"a/b":{"~key":"escaped"}})",
+        R"({"same":1})",
+        R"({"same":"1"})",
+        R"({"same":false})",
+        R"({"same":null})",
+        "",
+    });
+    std::vector<milvus::FieldDataPtr> field_datas = {
+        first,
+        CreateJsonFieldData(0),
+        second,
+    };
+
+    auto infos = ExpectParallelCollectMatchesLegacy(
+        field_datas, false, {1, 2, 5, 16, 64}, {1, 2, 4});
+
+    ExpectHitCount(infos, JsonKey{"", JSONType::INT64}, 3);
+    ExpectHitCount(infos, JsonKey{"", JSONType::DOUBLE}, 2);
+    ExpectHitCount(infos, JsonKey{"", JSONType::BOOL}, 2);
+    ExpectHitCount(infos, JsonKey{"", JSONType::NONE}, 1);
+    ExpectHitCount(infos, JsonKey{"", JSONType::STRING}, 1);
+    ExpectHitCount(infos, JsonKey{"", JSONType::ARRAY}, 2);
+    ExpectHitCount(infos, JsonKey{"/l1/l2/l3/int", JSONType::INT64}, 1);
+    ExpectHitCount(infos, JsonKey{"/a~1b/~0key", JSONType::STRING}, 1);
+    ExpectHitCount(infos, JsonKey{"/same", JSONType::INT64}, 1);
+    ExpectHitCount(infos, JsonKey{"/same", JSONType::STRING}, 1);
+    ExpectHitCount(infos, JsonKey{"/same", JSONType::BOOL}, 1);
+    ExpectHitCount(infos, JsonKey{"/same", JSONType::NONE}, 1);
+}
+
+TEST_F(JsonStatsCollectKeyInfoTest, ParallelMatchesLegacyForNullableRows) {
+    auto first = CreateNullableJsonFieldData(
+        {
+            R"({"kept":1})",
+            R"({"broken":)",
+            R"({"kept":2,"nested":{"flag":true}})",
+            "not-json",
+        },
+        {true, false, true, false});
+    auto second = CreateNullableJsonFieldData(
+        {
+            R"({"ignored":1})",
+            R"({"kept":"two"})",
+            R"({"nested":{"flag":false}})",
+        },
+        {false, true, true});
+    auto non_nullable =
+        CreateJsonFieldData(std::vector<std::string>{R"({"always":true})"});
+    std::vector<milvus::FieldDataPtr> field_datas = {
+        first,
+        CreateNullableJsonFieldData({}, {}),
+        second,
+        non_nullable,
+    };
+
+    auto infos_with_field_nullable = ExpectParallelCollectMatchesLegacy(
+        field_datas, false, {1, 2, 3, 8}, {1, 4});
+    auto infos_with_explicit_nullable = ExpectParallelCollectMatchesLegacy(
+        field_datas, true, {1, 2, 3, 8}, {1, 4});
+    ExpectKeyInfoMapsEqual(infos_with_field_nullable,
+                           infos_with_explicit_nullable);
+
+    ExpectHitCount(
+        infos_with_field_nullable, JsonKey{"/kept", JSONType::INT64}, 2);
+    ExpectHitCount(
+        infos_with_field_nullable, JsonKey{"/kept", JSONType::STRING}, 1);
+    ExpectHitCount(
+        infos_with_field_nullable, JsonKey{"/nested/flag", JSONType::BOOL}, 2);
+    ExpectHitCount(
+        infos_with_field_nullable, JsonKey{"/always", JSONType::BOOL}, 1);
+    EXPECT_EQ(
+        infos_with_field_nullable.count(JsonKey{"/ignored", JSONType::INT64}),
+        0);
+}
+
+TEST_F(JsonStatsCollectKeyInfoTest, ParallelMatchesLegacyAcrossManyRangeSizes) {
+    std::vector<milvus::FieldDataPtr> field_datas = {
+        CreateJsonFieldData(0),
+        CreateJsonFieldData(std::vector<std::string>{R"({"value":1})"}),
+        CreateJsonFieldData(0),
+        CreateJsonFieldData(std::vector<std::string>{
+            R"({"value":2})",
+            R"({"value":3})",
+            R"({"value":"three"})",
+            R"({"nested":{"value":4}})",
+            R"({"array":[1,2,3]})",
+            R"({"flag":true})",
+            R"({"null_value":null})",
+        }),
+        CreateJsonFieldData(0),
+        CreateJsonFieldData(std::vector<std::string>{
+            R"({"value":5})",
+            R"({"value":6})",
+            R"({"value":7})",
+        }),
+    };
+
+    auto infos = ExpectParallelCollectMatchesLegacy(
+        field_datas, false, {1, 2, 3, 4, 5, 8, 11, 32}, {1, 2, 4});
+    ExpectHitCount(infos, JsonKey{"/value", JSONType::INT64}, 6);
+    ExpectHitCount(infos, JsonKey{"/value", JSONType::STRING}, 1);
+}
+
+TEST_F(JsonStatsCollectKeyInfoTest,
+       ParallelMatchesLegacyForLargeMultiRangeInput) {
+    constexpr int64_t kRowsPerRange = 16 * 1024;
+    std::vector<milvus::FieldDataPtr> field_datas = {
+        CreateJsonFieldData(kRowsPerRange - 1),
+        CreateJsonFieldData(2),
+        CreateJsonFieldData(kRowsPerRange),
+    };
+
+    auto infos = ExpectParallelCollectMatchesLegacy(
+        field_datas, false, {kRowsPerRange}, {1, 4});
+    ExpectHitCount(
+        infos, JsonKey{"/value", JSONType::INT64}, 2 * kRowsPerRange + 1);
+}
+
+TEST_F(JsonStatsCollectKeyInfoTest, LegacyAndParallelRethrowSameParseError) {
+    auto invalid =
+        CreateJsonFieldData(std::vector<std::string>{R"({"broken":)"});
+    auto valid = CreateJsonFieldData(
+        std::vector<std::string>{R"({"value":1})", R"({"value":2})"});
+    std::vector<milvus::FieldDataPtr> field_datas = {invalid, valid};
+    auto ranges = milvus::index::CreateJsonStatsRowRanges(field_datas, 1);
+
+    milvus::ErrorCode legacy_error_code = milvus::UnexpectedError;
+    std::string legacy_error_message;
+    auto legacy_stats = CreateJsonKeyStatsForCollectTest();
+    try {
+        CollectKeyInfoAccessor::CallLegacy(*legacy_stats, field_datas, false);
+        FAIL() << "expected invalid JSON to fail in legacy collect";
+    } catch (const milvus::SegcoreError& error) {
+        legacy_error_code = error.get_error_code();
+        legacy_error_message = error.what();
+        EXPECT_EQ(legacy_error_code, milvus::DataFormatBroken);
+        EXPECT_NE(legacy_error_message.find("Failed to parse Json"),
+                  std::string::npos);
+    }
+
+    for (int worker_count : {1, 4}) {
+        SCOPED_TRACE(::testing::Message() << "worker_count=" << worker_count);
+        executor_set_json_stats_build_thread_num(worker_count);
+        auto parallel_stats = CreateJsonKeyStatsForCollectTest();
+        try {
+            CollectKeyInfoAccessor::CallParallel(
+                *parallel_stats, ranges, false);
+            FAIL() << "expected invalid JSON to fail in parallel collect";
+        } catch (const milvus::SegcoreError& error) {
+            EXPECT_EQ(error.get_error_code(), legacy_error_code);
+            EXPECT_EQ(std::string(error.what()), legacy_error_message);
+        }
+        EXPECT_EQ(
+            milvus::futures::getJsonStatsBuildExecutor()->getTaskQueueSize(),
+            0);
+    }
+}
+
 TEST(TraverseJsonForBuildStatsTest,
      HandlesPrimitivesArraysNestedAndEmptyObject) {
     const char* json = R"(

internal/core/unittest/test_json_stats/test_utils.cpp

@@ -7,6 +7,7 @@
 #include <map>
 #include <memory>
 #include <optional>
+#include <set>
 #include <string>
 #include <unordered_map>
 #include <utility>
@@ -50,13 +51,55 @@ TEST_F(UtilsTest, CreateArrowBuildersTest) {
 
     auto [builders, builders_map] = CreateArrowBuilders(column_map);
     EXPECT_EQ(builders.size(), column_map.size());
-    EXPECT_EQ(builders_map.size(), column_map.size());
+    EXPECT_EQ(builders_map.size(), column_map.size() - 1);
+    EXPECT_EQ(builders_map.count(
+                  JsonKey("shared_key", JSONType::STRING).ToColumnName()),
+              0);
 
     auto schema = CreateArrowSchema(column_map);
     EXPECT_NE(schema, nullptr);
     EXPECT_EQ(schema->num_fields(), column_map.size());
 }
 
+TEST_F(UtilsTest, SharedKeysDoNotExpandTaskLocalBuilders) {
+    std::map<JsonKey, JsonKeyLayoutType> column_map = {
+        {JsonKey("/typed", JSONType::INT64), JsonKeyLayoutType::TYPED},
+        {JsonKey("/dynamic", JSONType::STRING), JsonKeyLayoutType::DYNAMIC},
+    };
+    std::set<JsonKey> column_keys;
+    for (const auto& entry : column_map) {
+        column_keys.insert(entry.first);
+    }
+    for (size_t i = 0; i < 4096; ++i) {
+        column_map.emplace(
+            JsonKey("/shared/" + std::to_string(i), JSONType::STRING),
+            JsonKeyLayoutType::SHARED);
+    }
+
+    auto [writer_builders, writer_map] = CreateArrowBuilders(column_map);
+    auto [task_builders, task_map] = CreateArrowBuildersForColumns(column_keys);
+    auto schema = CreateArrowSchema(column_map);
+
+    ASSERT_NE(schema, nullptr);
+    ASSERT_EQ(schema->num_fields(), 3);
+    ASSERT_EQ(writer_builders.size(), 3);
+    ASSERT_EQ(task_builders.size(), 3);
+    EXPECT_EQ(writer_map.size(), column_keys.size());
+    EXPECT_EQ(task_map.size(), column_keys.size());
+    EXPECT_EQ(
+        writer_map.count(JsonKey("/shared/0", JSONType::STRING).ToColumnName()),
+        0);
+    size_t column_index = 0;
+    for (const auto& key : column_keys) {
+        const auto name = key.ToColumnName();
+        EXPECT_EQ(schema->field(column_index)->name(), name);
+        EXPECT_EQ(writer_map.at(name), writer_builders[column_index]);
+        EXPECT_EQ(task_map.at(name), task_builders[column_index]);
+        ++column_index;
+    }
+    EXPECT_EQ(task_builders.back()->type()->id(), arrow::Type::BINARY);
+}
+
 TEST_F(UtilsTest, CreateParquetKVMetadataTest) {
     std::map<JsonKey, JsonKeyLayoutType> column_map = {
         {JsonKey("int_key", JSONType::INT64), JsonKeyLayoutType::TYPED},
@@ -229,4 +272,4 @@ TEST_F(JsonStatsMetaTest, EmptyLayoutTypeMapTest) {
     EXPECT_TRUE(key_field_map.empty());
 }
 
-}  // namespace milvus::index
+}  // namespace milvus::index

internal/datanode/index/init_segcore.go

@@ -70,6 +70,14 @@ func InitSegcore(nodeID int64) error {
 
 	cCPUNum := C.int(hardware.GetCPUNum())
 	C.InitCpuNum(cCPUNum)
+	if err := initcore.UpdateJSONStatsBuildExecutorPoolSize(
+		initcore.ResolveJSONStatsBuildExecutorPoolSize(paramtable.Get())); err != nil {
+		return err
+	}
+	if err := initcore.UpdateJSONStatsBuildMaxInflightBytes(
+		initcore.ResolveJSONStatsBuildMaxInflightBytes(paramtable.Get())); err != nil {
+		return err
+	}
 
 	cKnowhereThreadPoolSize := C.uint32_t(hardware.GetCPUNum() * paramtable.DefaultKnowhereThreadPoolNumRatioInBuild)
 	if paramtable.GetRole() == typeutil.StandaloneRole {
@@ -121,6 +129,8 @@ func InitSegcore(nodeID int64) error {
 	initcore.RegisterArrowIOThreadPoolWatchers(paramtable.Get(), "datanode")
 	initcore.RegisterArrowReaderConfigWatchers(paramtable.Get(), "datanode")
 	initcore.RegisterLoonReaderConfigWatchers(paramtable.Get(), "datanode")
+	initcore.RegisterJSONStatsBuildExecutorWatcher(paramtable.Get(), "datanode")
+	initcore.RegisterJSONStatsBuildMemoryBudgetWatcher(paramtable.Get(), "datanode")
 
 	// init paramtable change callback for core related config
 	initcore.SetupCoreConfigChangelCallback()

internal/util/initcore/json_stats_executor.go

@@ -0,0 +1,132 @@
+// Licensed to the LF AI & Data foundation under one
+// or more contributor license agreements. See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership. The ASF licenses this file
+// to you 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.
+
+package initcore
+
+/*
+#cgo pkg-config: milvus_core
+
+#include "futures/future_c.h"
+*/
+import "C"
+
+import (
+	"context"
+
+	"github.com/milvus-io/milvus/pkg/v3/config"
+	"github.com/milvus-io/milvus/pkg/v3/mlog"
+	"github.com/milvus-io/milvus/pkg/v3/util/hardware"
+	"github.com/milvus-io/milvus/pkg/v3/util/paramtable"
+)
+
+const defaultJSONStatsBuildMaxWorkers = 8
+
+// ResolveJSONStatsBuildExecutorPoolSize returns the process-wide hard worker
+// limit after applying the safe automatic default and the cgroup-aware CPU cap.
+func ResolveJSONStatsBuildExecutorPoolSize(pt *paramtable.ComponentParam) int {
+	cpuNum := hardware.GetCPUNum()
+	if cpuNum < 1 {
+		cpuNum = 1
+	}
+
+	maxWorkers := pt.DataNodeCfg.JSONStatsBuildMaxWorkers.GetAsInt()
+	if maxWorkers <= 0 {
+		maxWorkers = defaultJSONStatsBuildMaxWorkers
+	}
+	if maxWorkers > cpuNum {
+		maxWorkers = cpuNum
+	}
+	return maxWorkers
+}
+
+// UpdateJSONStatsBuildExecutorPoolSize resizes the C++ Folly executor.
+func UpdateJSONStatsBuildExecutorPoolSize(threads int) error {
+	if threads < 1 {
+		threads = 1
+	}
+	status := C.executor_set_json_stats_build_thread_num(C.int(threads))
+	return HandleCStatus(&status, "failed to resize json stats build executor")
+}
+
+// ResolveJSONStatsBuildMaxInflightBytes returns the process-wide materialized
+// chunk budget. Zero disables the byte limit.
+func ResolveJSONStatsBuildMaxInflightBytes(pt *paramtable.ComponentParam) int64 {
+	maxInflightBytes := pt.DataNodeCfg.JSONStatsBuildMaxInflightBytes.GetAsInt64()
+	if maxInflightBytes < 0 {
+		return paramtable.DefaultJSONStatsBuildMaxInflightBytes
+	}
+	return maxInflightBytes
+}
+
+// UpdateJSONStatsBuildMaxInflightBytes updates the C++ shared byte budget.
+func UpdateJSONStatsBuildMaxInflightBytes(maxInflightBytes int64) error {
+	if maxInflightBytes < 0 {
+		maxInflightBytes = paramtable.DefaultJSONStatsBuildMaxInflightBytes
+	}
+	status := C.executor_set_json_stats_build_max_inflight_bytes(C.int64_t(maxInflightBytes))
+	return HandleCStatus(&status, "failed to update json stats build memory budget")
+}
+
+// RegisterJSONStatsBuildExecutorWatcher applies maxWorkers updates without
+// interrupting tasks already running in the executor.
+func RegisterJSONStatsBuildExecutorWatcher(pt *paramtable.ComponentParam, source string) {
+	key := pt.DataNodeCfg.JSONStatsBuildMaxWorkers.Key
+	handler := func(evt *config.Event) {
+		if !evt.HasUpdated {
+			return
+		}
+		threads := ResolveJSONStatsBuildExecutorPoolSize(pt)
+		if err := UpdateJSONStatsBuildExecutorPoolSize(threads); err != nil {
+			mlog.Warn(context.TODO(), "failed to resize json stats build executor",
+				mlog.String("source", source),
+				mlog.String("trigger", key),
+				mlog.Int("threads", threads),
+				mlog.Err(err))
+			return
+		}
+		mlog.Info(context.TODO(), "json stats build executor resized",
+			mlog.String("source", source),
+			mlog.String("trigger", key),
+			mlog.Int("threads", threads))
+	}
+	pt.Watch(key, config.NewHandler("json-stats-build-executor."+source+"."+key, handler))
+}
+
+// RegisterJSONStatsBuildMemoryBudgetWatcher applies maxInflightBytes updates.
+// Shrinking the budget does not interrupt active chunks; it only blocks later
+// dispatch until current reservations fall below the new capacity.
+func RegisterJSONStatsBuildMemoryBudgetWatcher(pt *paramtable.ComponentParam, source string) {
+	key := pt.DataNodeCfg.JSONStatsBuildMaxInflightBytes.Key
+	handler := func(evt *config.Event) {
+		if !evt.HasUpdated {
+			return
+		}
+		maxInflightBytes := ResolveJSONStatsBuildMaxInflightBytes(pt)
+		if err := UpdateJSONStatsBuildMaxInflightBytes(maxInflightBytes); err != nil {
+			mlog.Warn(context.TODO(), "failed to resize json stats build memory budget",
+				mlog.String("source", source),
+				mlog.String("trigger", key),
+				mlog.Int64("maxInflightBytes", maxInflightBytes),
+				mlog.Err(err))
+			return
+		}
+		mlog.Info(context.TODO(), "json stats build memory budget resized",
+			mlog.String("source", source),
+			mlog.String("trigger", key),
+			mlog.Int64("maxInflightBytes", maxInflightBytes))
+	}
+	pt.Watch(key, config.NewHandler("json-stats-build-memory-budget."+source+"."+key, handler))
+}

internal/util/initcore/json_stats_executor_test.go

@@ -0,0 +1,99 @@
+// Licensed to the LF AI & Data foundation under one
+// or more contributor license agreements. See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership. The ASF licenses this file
+// to you 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.
+
+package initcore
+
+import (
+	"sync/atomic"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"github.com/milvus-io/milvus/pkg/v3/config"
+	"github.com/milvus-io/milvus/pkg/v3/util/hardware"
+	"github.com/milvus-io/milvus/pkg/v3/util/paramtable"
+)
+
+func TestJSONStatsBuildExecutorConfig(t *testing.T) {
+	paramtable.Init()
+	pt := paramtable.Get()
+	key := pt.DataNodeCfg.JSONStatsBuildMaxWorkers.Key
+	require.NoError(t, pt.Reset(key))
+	defer pt.Reset(key)
+
+	cpuNum := hardware.GetCPUNum()
+	if cpuNum < 1 {
+		cpuNum = 1
+	}
+
+	assert.Equal(t, min(defaultJSONStatsBuildMaxWorkers, cpuNum),
+		ResolveJSONStatsBuildExecutorPoolSize(pt))
+
+	require.NoError(t, pt.Save(key, "2"))
+	assert.Equal(t, min(2, cpuNum), ResolveJSONStatsBuildExecutorPoolSize(pt))
+
+	require.NoError(t, pt.Save(key, "0"))
+	assert.Equal(t, min(defaultJSONStatsBuildMaxWorkers, cpuNum),
+		ResolveJSONStatsBuildExecutorPoolSize(pt))
+	require.NoError(t, UpdateJSONStatsBuildExecutorPoolSize(1))
+
+	RegisterJSONStatsBuildExecutorWatcher(pt, "test")
+	var watcherFires atomic.Int32
+	sentinel := config.NewHandler("json-stats-build-executor-sentinel", func(*config.Event) {
+		watcherFires.Add(1)
+	})
+	pt.Watch(key, sentinel)
+	defer pt.Unwatch(key, sentinel)
+
+	require.NoError(t, pt.Save(key, "1"))
+	assert.Positive(t, watcherFires.Load())
+}
+
+func TestJSONStatsBuildMemoryBudgetConfig(t *testing.T) {
+	paramtable.Init()
+	pt := paramtable.Get()
+	key := pt.DataNodeCfg.JSONStatsBuildMaxInflightBytes.Key
+	require.NoError(t, pt.Reset(key))
+	defer pt.Reset(key)
+
+	assert.Equal(t, int64(paramtable.DefaultJSONStatsBuildMaxInflightBytes),
+		ResolveJSONStatsBuildMaxInflightBytes(pt))
+
+	require.NoError(t, pt.Save(key, "67108864"))
+	assert.Equal(t, int64(67108864), ResolveJSONStatsBuildMaxInflightBytes(pt))
+
+	require.NoError(t, pt.Save(key, "0"))
+	assert.Zero(t, ResolveJSONStatsBuildMaxInflightBytes(pt))
+
+	require.NoError(t, pt.Save(key, "-1"))
+	assert.Equal(t, int64(paramtable.DefaultJSONStatsBuildMaxInflightBytes),
+		ResolveJSONStatsBuildMaxInflightBytes(pt))
+
+	require.NoError(t, UpdateJSONStatsBuildMaxInflightBytes(0))
+	require.NoError(t, UpdateJSONStatsBuildMaxInflightBytes(128*1024*1024))
+
+	RegisterJSONStatsBuildMemoryBudgetWatcher(pt, "test")
+	var watcherFires atomic.Int32
+	sentinel := config.NewHandler("json-stats-build-memory-budget-sentinel", func(*config.Event) {
+		watcherFires.Add(1)
+	})
+	pt.Watch(key, sentinel)
+	defer pt.Unwatch(key, sentinel)
+
+	require.NoError(t, pt.Save(key, "33554432"))
+	assert.Positive(t, watcherFires.Load())
+}

pkg/util/paramtable/component_param.go

@@ -46,8 +46,9 @@ const (
 	DefaultIndexSliceSize = 16
 	// Load admission defaults apply only when async loading is enabled and the
 	// corresponding parameter is absent. Explicit values, including 0, win.
-	DefaultLoadTransientBudgetBytes = 2 * 1024 * 1024 * 1024
-	DefaultLoadAdmissionSlotsPerCPU = 2
+	DefaultLoadTransientBudgetBytes       = 2 * 1024 * 1024 * 1024
+	DefaultLoadAdmissionSlotsPerCPU       = 2
+	DefaultJSONStatsBuildMaxInflightBytes = 512 * 1024 * 1024
 	// DefaultStorageV2AsyncLoadReadWindowSizeBytes is the historical-key
 	// default for the Storage V3 async read-window threshold.
 	DefaultStorageV2AsyncLoadReadWindowSizeBytes = 16 * 1024 * 1024
@@ -8088,13 +8089,21 @@ re-ingesting. A job that timed out before applying carries 0 and left the collec
 	}
 	p.JSONStatsShreddingRatioThreshold.Init(base.mgr)
 
+	const defaultJSONStatsWriteBatchSize = "81920"
 	p.JSONStatsWriteBatchSize = ParamItem{
 		Key:          "dataCoord.jsonShreddingWriteBatchSize",
 		Version:      "2.6.5",
-		DefaultValue: "81920",
-		Doc:          "the batch size to write",
+		DefaultValue: defaultJSONStatsWriteBatchSize,
+		Doc:          "the batch size to write; values must be positive, otherwise the default is used",
 		FallbackKeys: []string{"dataCoord.jsonStatsWriteBatchSize"},
 		Export:       true,
+		Formatter: func(value string) string {
+			batchSize, err := strconv.ParseInt(value, 10, 64)
+			if err != nil || batchSize <= 0 {
+				return defaultJSONStatsWriteBatchSize
+			}
+			return value
+		},
 	}
 	p.JSONStatsWriteBatchSize.Init(base.mgr)
 }
@@ -8187,8 +8196,10 @@ type dataNodeConfig struct {
 	DeltalogFormat ParamItem `refreshable:"false"`
 
 	// index services config
-	BuildParallel               ParamItem `refreshable:"false"`
-	MaxVecIndexBuildConcurrency ParamItem `refreshable:"true"`
+	BuildParallel                  ParamItem `refreshable:"false"`
+	MaxVecIndexBuildConcurrency    ParamItem `refreshable:"true"`
+	JSONStatsBuildMaxWorkers       ParamItem `refreshable:"true"`
+	JSONStatsBuildMaxInflightBytes ParamItem `refreshable:"true"`
 
 	WorkerSlotUnit      ParamItem `refreshable:"true"`
 	StandaloneSlotRatio ParamItem `refreshable:"false"`
@@ -8748,6 +8759,37 @@ writeRetryInitialInterval, otherwise the effective cap is raised to twice the in
 	}
 	p.MaxVecIndexBuildConcurrency.Init(base.mgr)
 
+	p.JSONStatsBuildMaxWorkers = ParamItem{
+		Key:          "dataNode.jsonStats.parallelBuild.maxWorkers",
+		Version:      "3.0.1",
+		DefaultValue: "8",
+		Doc:          "Maximum number of process-wide JSON Stats Build workers. The effective value is capped by the cgroup-aware CPU count. Values less than or equal to 0 use the safe automatic limit min(CPU, 8).",
+		Export:       true,
+	}
+	p.JSONStatsBuildMaxWorkers.Init(base.mgr)
+
+	p.JSONStatsBuildMaxInflightBytes = ParamItem{
+		Key:          "dataNode.jsonStats.parallelBuild.maxInflightBytes",
+		Version:      "3.0.1",
+		DefaultValue: strconv.Itoa(DefaultJSONStatsBuildMaxInflightBytes),
+		Doc: `Process-wide transient memory budget in bytes for materialized JSON Stats Build chunks. ` +
+			`The budget is shared by concurrent builds. Lower values reduce peak memory at the cost of ` +
+			`parallelism. A chunk larger than the budget is allowed to run exclusively to guarantee ` +
+			`progress. Set to 0 to disable the limit.`,
+		Export: true,
+		Formatter: func(v string) string {
+			value, err := strconv.ParseInt(v, 10, 64)
+			if err != nil || value < 0 {
+				mlog.Warn(context.TODO(), "dataNode.jsonStats.parallelBuild.maxInflightBytes must be non-negative, using default",
+					mlog.String("configured", v),
+					mlog.Int64("default", DefaultJSONStatsBuildMaxInflightBytes))
+				return strconv.Itoa(DefaultJSONStatsBuildMaxInflightBytes)
+			}
+			return v
+		},
+	}
+	p.JSONStatsBuildMaxInflightBytes.Init(base.mgr)
+
 	p.WorkerSlotUnit = ParamItem{
 		Key:          "dataNode.workerSlotUnit",
 		Version:      "2.5.7",

pkg/util/paramtable/component_param_test.go

@@ -129,6 +129,33 @@ func TestComponentParam_DataCoordSnapshotExportCopyConcurrency(t *testing.T) {
 	}
 }
 
+func TestComponentParam_DataCoordJSONStatsWriteBatchSize(t *testing.T) {
+	Init()
+	params := Get()
+	item := &params.DataCoordCfg.JSONStatsWriteBatchSize
+	legacyKey := item.FallbackKeys[0]
+	params.Reset(item.Key)
+	params.Reset(legacyKey)
+	t.Cleanup(func() {
+		params.Reset(item.Key)
+		params.Reset(legacyKey)
+	})
+
+	assert.EqualValues(t, 81920, item.GetAsInt64())
+
+	params.Save(item.Key, "4096")
+	assert.EqualValues(t, 4096, item.GetAsInt64())
+
+	for _, invalid := range []string{"0", "-1", "invalid", "9223372036854775808"} {
+		params.Save(item.Key, invalid)
+		assert.EqualValues(t, 81920, item.GetAsInt64(), invalid)
+	}
+
+	params.Reset(item.Key)
+	params.Save(legacyKey, "-1")
+	assert.EqualValues(t, 81920, item.GetAsInt64())
+}
+
 func TestMembershipFilterConfig(t *testing.T) {
 	base := NewBaseTable(SkipRemote(true))
 	params := proxyConfig{}
@@ -1260,6 +1287,22 @@ func TestComponentParam(t *testing.T) {
 		assert.Equal(t, 10, Params.MaxCompactionConcurrency.GetAsInt())
 
 		assert.Equal(t, 4, Params.MaxVecIndexBuildConcurrency.GetAsInt())
+		assert.Equal(t, 8, Params.JSONStatsBuildMaxWorkers.GetAsInt())
+		assert.Equal(t, int64(DefaultJSONStatsBuildMaxInflightBytes),
+			Params.JSONStatsBuildMaxInflightBytes.GetAsInt64())
+		params.Save(Params.JSONStatsBuildMaxInflightBytes.Key, "-1")
+		assert.Equal(t, int64(DefaultJSONStatsBuildMaxInflightBytes),
+			Params.JSONStatsBuildMaxInflightBytes.GetAsInt64())
+		params.Save(Params.JSONStatsBuildMaxInflightBytes.Key, "invalid")
+		assert.Equal(t, int64(DefaultJSONStatsBuildMaxInflightBytes),
+			Params.JSONStatsBuildMaxInflightBytes.GetAsInt64())
+		params.Save(Params.JSONStatsBuildMaxInflightBytes.Key, "0")
+		assert.Equal(t, int64(0),
+			Params.JSONStatsBuildMaxInflightBytes.GetAsInt64())
+		params.Save(Params.JSONStatsBuildMaxInflightBytes.Key, "67108864")
+		assert.Equal(t, int64(67108864),
+			Params.JSONStatsBuildMaxInflightBytes.GetAsInt64())
+		params.Reset(Params.JSONStatsBuildMaxInflightBytes.Key)
 
 		// clustering compaction
 		params.Save("datanode.clusteringCompaction.memoryBufferRatio", "0.1")

scripts/segcore_error_boundary_baseline.txt

@@ -85,6 +85,7 @@ arrow	internal/core/src/common/Schema.cpp
 arrow	internal/core/src/common/Schema.h
 arrow	internal/core/src/common/Types.h
 arrow	internal/core/src/index/json_stats/JsonKeyStats.cpp
+arrow	internal/core/src/index/json_stats/JsonKeyStats.h
 arrow	internal/core/src/index/json_stats/parquet_writer.cpp
 arrow	internal/core/src/index/json_stats/parquet_writer.h
 arrow	internal/core/src/index/json_stats/utils.cpp