feat: support json for ngram (#43170)

Ref https://github.com/milvus-io/milvus/issues/42053

This PR enable ngram to support json data type.

---------

Signed-off-by: SpadeA <tangchenjie1210@gmail.com>

internal/core/src/exec/expression/Expr.h

@@ -1283,11 +1283,13 @@ class SegmentExpr : public Expr {
 
     bool
     CanUseNgramIndex(FieldId field_id) const {
-        if (segment_->type() != SegmentType::Sealed) {
-            return false;
-        }
-        auto cast_ptr = dynamic_cast<const segcore::SegmentSealed*>(segment_);
-        return (cast_ptr != nullptr && cast_ptr->HasNgramIndex(field_id));
+        return segment_->HasNgramIndex(field_id);
+    }
+
+    bool
+    CanUseNgramIndexForJson(FieldId field_id,
+                            const std::string& nested_path) const {
+        return segment_->HasNgramIndexForJson(field_id, nested_path);
     }
 
  protected:

internal/core/src/exec/expression/UnaryExpr.cpp

@@ -197,8 +197,19 @@ PhyUnaryRangeFilterExpr::Eval(EvalCtx& context, VectorPtr& result) {
         }
         case DataType::JSON: {
             auto val_type = expr_->val_.val_case();
-            if (CanUseIndexForJson(FromValCase(val_type)) &&
+            auto val_type_inner = FromValCase(val_type);
+            if (CanExecNgramMatchForJson(val_type_inner) &&
                 !has_offset_input_) {
+                auto res = ExecNgramMatch();
+                // If nullopt is returned, it means the query cannot be
+                // optimized by ngram index. Forward it to the normal path.
+                if (res.has_value()) {
+                    result = res.value();
+                    break;
+                }
+            }
+
+            if (CanUseIndexForJson(val_type_inner) && !has_offset_input_) {
                 switch (val_type) {
                     case proto::plan::GenericValue::ValCase::kBoolVal:
                         result = ExecRangeVisitorImplForIndex<bool>();
@@ -1885,6 +1896,7 @@ PhyUnaryRangeFilterExpr::CanUseIndexForJson(DataType val_type) {
                            val_type);
     switch (val_type) {
         case DataType::STRING:
+        case DataType::VARCHAR:
             use_index_ = has_index &&
                          expr_->op_type_ != proto::plan::OpType::Match &&
                          expr_->op_type_ != proto::plan::OpType::PostfixMatch &&
@@ -1974,6 +1986,18 @@ PhyUnaryRangeFilterExpr::CanExecNgramMatch(proto::plan::OpType op_type) {
            !has_offset_input_ && CanUseNgramIndex(field_id_);
 }
 
+bool
+PhyUnaryRangeFilterExpr::CanExecNgramMatchForJson(DataType val_type) {
+    return (val_type == DataType::STRING || val_type == DataType::VARCHAR) &&
+           (expr_->op_type_ == proto::plan::OpType::InnerMatch ||
+            expr_->op_type_ == proto::plan::OpType::Match ||
+            expr_->op_type_ == proto::plan::OpType::PrefixMatch ||
+            expr_->op_type_ == proto::plan::OpType::PostfixMatch) &&
+           !has_offset_input_ &&
+           CanUseNgramIndexForJson(
+               field_id_, milvus::Json::pointer(expr_->column_.nested_path_));
+}
+
 std::optional<VectorPtr>
 PhyUnaryRangeFilterExpr::ExecNgramMatch() {
     if (!arg_inited_) {
@@ -1988,8 +2012,15 @@ PhyUnaryRangeFilterExpr::ExecNgramMatch() {
     }
 
     if (cached_ngram_match_res_ == nullptr) {
-        auto pinned_index = segment_->GetNgramIndex(field_id_);
-        auto index = pinned_index.get();
+        index::NgramInvertedIndex* index;
+        if (expr_->column_.data_type_ == DataType::JSON) {
+            auto pinned_index = segment_->GetNgramIndexForJson(
+                field_id_, milvus::Json::pointer(expr_->column_.nested_path_));
+            index = pinned_index.get();
+        } else {
+            auto pinned_index = segment_->GetNgramIndex(field_id_);
+            index = pinned_index.get();
+        }
         AssertInfo(index != nullptr,
                    "ngram index should not be null, field_id: {}",
                    field_id_.get());

internal/core/src/exec/expression/UnaryExpr.h

@@ -509,6 +509,9 @@ class PhyUnaryRangeFilterExpr : public SegmentExpr {
     bool
     CanExecNgramMatch(proto::plan::OpType op_type);
 
+    bool
+    CanExecNgramMatchForJson(DataType val_type);
+
     std::optional<VectorPtr>
     ExecNgramMatch();
 

internal/core/src/index/IndexFactory.cpp

@@ -67,28 +67,6 @@ IndexFactory::CreatePrimitiveScalarIndex(
     return CreateScalarIndexSort<T>(file_manager_context);
 }
 
-IndexBasePtr
-IndexFactory::CreateNgramIndex(
-    DataType data_type,
-    const NgramParams& params,
-    const storage::FileManagerContext& file_manager_context) {
-    switch (data_type) {
-        case DataType::VARCHAR:
-        case DataType::STRING:
-            return std::make_unique<NgramInvertedIndex>(file_manager_context,
-                                                        params);
-
-        case DataType::JSON:
-            ThrowInfo(
-                NotImplemented,
-                fmt::format("building ngram index in json is not implemented"));
-        default:
-            ThrowInfo(DataTypeInvalid,
-                      fmt::format("invalid data type to build ngram index: {}",
-                                  data_type));
-    }
-}
-
 template <>
 ScalarIndexPtr<std::string>
 IndexFactory::CreatePrimitiveScalarIndex<std::string>(
@@ -364,8 +342,8 @@ IndexFactory::CreatePrimitiveScalarIndex(
         case DataType::VARCHAR: {
             auto& ngram_params = create_index_info.ngram_params;
             if (ngram_params.has_value()) {
-                return CreateNgramIndex(
-                    data_type, ngram_params.value(), file_manager_context);
+                return std::make_unique<NgramInvertedIndex>(
+                    file_manager_context, ngram_params.value());
             }
             return CreatePrimitiveScalarIndex<std::string>(
                 create_index_info, file_manager_context);
@@ -405,14 +383,15 @@ IndexFactory::CreateComplexScalarIndex(
 
 IndexBasePtr
 IndexFactory::CreateJsonIndex(
-    IndexType index_type,
-    JsonCastType cast_dtype,
-    const std::string& nested_path,
-    const storage::FileManagerContext& file_manager_context,
-    const std::string& json_cast_function) {
-    AssertInfo(index_type == INVERTED_INDEX_TYPE,
+    const CreateIndexInfo& create_index_info,
+    const storage::FileManagerContext& file_manager_context) {
+    AssertInfo(create_index_info.index_type == INVERTED_INDEX_TYPE ||
+                   create_index_info.index_type == NGRAM_INDEX_TYPE,
                "Invalid index type for json index");
 
+    const auto& cast_dtype = create_index_info.json_cast_type;
+    const auto& nested_path = create_index_info.json_path;
+    const auto& json_cast_function = create_index_info.json_cast_function;
     switch (cast_dtype.element_type()) {
         case JsonCastType::DataType::BOOL:
             return std::make_unique<index::JsonInvertedIndex<bool>>(
@@ -426,12 +405,18 @@ IndexFactory::CreateJsonIndex(
                 nested_path,
                 file_manager_context,
                 JsonCastFunction::FromString(json_cast_function));
-        case JsonCastType::DataType::VARCHAR:
+        case JsonCastType::DataType::VARCHAR: {
+            auto& ngram_params = create_index_info.ngram_params;
+            if (ngram_params.has_value()) {
+                return std::make_unique<NgramInvertedIndex>(
+                    file_manager_context, ngram_params.value(), nested_path);
+            }
             return std::make_unique<index::JsonInvertedIndex<std::string>>(
                 cast_dtype,
                 nested_path,
                 file_manager_context,
                 JsonCastFunction::FromString(json_cast_function));
+        }
         case JsonCastType::DataType::JSON:
             return std::make_unique<JsonFlatIndex>(file_manager_context,
                                                    nested_path);
@@ -462,11 +447,7 @@ IndexFactory::CreateScalarIndex(
                                               file_manager_context);
         }
         case DataType::JSON: {
-            return CreateJsonIndex(create_index_info.index_type,
-                                   create_index_info.json_cast_type,
-                                   create_index_info.json_path,
-                                   file_manager_context,
-                                   create_index_info.json_cast_function);
+            return CreateJsonIndex(create_index_info, file_manager_context);
         }
         default:
             ThrowInfo(DataTypeInvalid, "Invalid data type:{}", data_type);

internal/core/src/index/IndexFactory.h

@@ -116,13 +116,9 @@ class IndexFactory {
             storage::FileManagerContext());
 
     IndexBasePtr
-    CreateJsonIndex(
-        IndexType index_type,
-        JsonCastType cast_dtype,
-        const std::string& nested_path,
-        const storage::FileManagerContext& file_manager_context =
-            storage::FileManagerContext(),
-        const std::string& json_cast_function = UNKNOW_CAST_FUNCTION_NAME);
+    CreateJsonIndex(const CreateIndexInfo& create_index_info,
+                    const storage::FileManagerContext& file_manager_context =
+                        storage::FileManagerContext());
 
     IndexBasePtr
     CreateScalarIndex(const CreateIndexInfo& create_index_info,

internal/core/src/index/IndexInfo.h

@@ -17,6 +17,7 @@
 
 #include "common/JsonCastType.h"
 #include "common/Types.h"
+#include "common/Consts.h"
 
 namespace milvus::index {
 
@@ -37,8 +38,8 @@ struct CreateIndexInfo {
     uint32_t tantivy_index_version{7};
     JsonCastType json_cast_type{JsonCastType::UNKNOWN};
     std::string json_path;
-    std::string json_cast_function;
-    std::optional<NgramParams> ngram_params;
+    std::string json_cast_function{UNKNOW_CAST_FUNCTION_NAME};
+    std::optional<NgramParams> ngram_params{std::nullopt};
 };
 
 }  // namespace milvus::index

internal/core/src/index/JsonIndexBuilder.cpp

@@ -0,0 +1,140 @@
+// Copyright (C) 2019-2020 Zilliz. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance
+// with the License. You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software distributed under the License
+// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
+// or implied. See the License for the specific language governing permissions and limitations under the License
+
+#include <string>
+#include <string_view>
+#include "common/JsonUtils.h"
+#include "index/JsonIndexBuilder.h"
+#include "simdjson/error.h"
+
+namespace milvus::index {
+
+template <typename T>
+void
+ProcessJsonFieldData(
+    const std::vector<std::shared_ptr<FieldDataBase>>& field_datas,
+    const proto::schema::FieldSchema& schema,
+    const std::string& nested_path,
+    const JsonCastType& cast_type,
+    JsonCastFunction cast_function,
+    JsonDataAdder<T> data_adder,
+    JsonNullAdder null_adder,
+    JsonErrorRecorder error_recorder) {
+    int64_t offset = 0;
+    using SIMDJSON_T =
+        std::conditional_t<std::is_same_v<T, std::string>, std::string_view, T>;
+
+    auto tokens = parse_json_pointer(nested_path);
+
+    bool is_array = cast_type.data_type() == JsonCastType::DataType::ARRAY;
+
+    for (const auto& data : field_datas) {
+        auto n = data->get_num_rows();
+        for (int64_t i = 0; i < n; i++) {
+            auto json_column = static_cast<const Json*>(data->RawValue(i));
+            if (schema.nullable() && !data->is_valid(i)) {
+                null_adder(offset++);
+                continue;
+            }
+
+            auto exists = path_exists(json_column->dom_doc(), tokens);
+            if (!exists || !json_column->exist(nested_path)) {
+                error_recorder(
+                    *json_column, nested_path, simdjson::NO_SUCH_FIELD);
+                null_adder(offset++);
+                continue;
+            }
+
+            folly::fbvector<T> values;
+            if (is_array) {
+                auto doc = json_column->dom_doc();
+                auto array_res = doc.at_pointer(nested_path).get_array();
+                if (array_res.error() != simdjson::SUCCESS) {
+                    error_recorder(
+                        *json_column, nested_path, array_res.error());
+                } else {
+                    auto array_values = array_res.value();
+                    for (auto value : array_values) {
+                        auto val = value.template get<SIMDJSON_T>();
+
+                        if (val.error() == simdjson::SUCCESS) {
+                            values.push_back(static_cast<T>(val.value()));
+                        }
+                    }
+                }
+            } else {
+                if (cast_function.match<T>()) {
+                    auto res = JsonCastFunction::CastJsonValue<T>(
+                        cast_function, *json_column, nested_path);
+                    if (res.has_value()) {
+                        values.push_back(res.value());
+                    }
+                } else {
+                    value_result<SIMDJSON_T> res =
+                        json_column->at<SIMDJSON_T>(nested_path);
+                    if (res.error() != simdjson::SUCCESS) {
+                        error_recorder(*json_column, nested_path, res.error());
+                    } else {
+                        values.push_back(static_cast<T>(res.value()));
+                    }
+                }
+            }
+
+            data_adder(values, offset++);
+        }
+    }
+}
+
+template void
+ProcessJsonFieldData<bool>(
+    const std::vector<std::shared_ptr<FieldDataBase>>& field_datas,
+    const proto::schema::FieldSchema& schema,
+    const std::string& nested_path,
+    const JsonCastType& cast_type,
+    JsonCastFunction cast_function,
+    JsonDataAdder<bool> data_adder,
+    JsonNullAdder null_adder,
+    JsonErrorRecorder error_recorder);
+
+template void
+ProcessJsonFieldData<int64_t>(
+    const std::vector<std::shared_ptr<FieldDataBase>>& field_datas,
+    const proto::schema::FieldSchema& schema,
+    const std::string& nested_path,
+    const JsonCastType& cast_type,
+    JsonCastFunction cast_function,
+    JsonDataAdder<int64_t> data_adder,
+    JsonNullAdder null_adder,
+    JsonErrorRecorder error_recorder);
+
+template void
+ProcessJsonFieldData<double>(
+    const std::vector<std::shared_ptr<FieldDataBase>>& field_datas,
+    const proto::schema::FieldSchema& schema,
+    const std::string& nested_path,
+    const JsonCastType& cast_type,
+    JsonCastFunction cast_function,
+    JsonDataAdder<double> data_adder,
+    JsonNullAdder null_adder,
+    JsonErrorRecorder error_recorder);
+
+template void
+ProcessJsonFieldData<std::string>(
+    const std::vector<std::shared_ptr<FieldDataBase>>& field_datas,
+    const proto::schema::FieldSchema& schema,
+    const std::string& nested_path,
+    const JsonCastType& cast_type,
+    JsonCastFunction cast_function,
+    JsonDataAdder<std::string> data_adder,
+    JsonNullAdder null_adder,
+    JsonErrorRecorder error_recorder);
+
+}  // namespace milvus::index

internal/core/src/index/JsonIndexBuilder.h

@@ -0,0 +1,88 @@
+// Copyright (C) 2019-2020 Zilliz. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance
+// with the License. You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software distributed under the License
+// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
+// or implied. See the License for the specific language governing permissions and limitations under the License
+
+#pragma once
+#include <functional>
+#include "common/JsonCastType.h"
+#include "common/JsonCastFunction.h"
+#include "common/Json.h"
+#include "folly/FBVector.h"
+
+namespace milvus::index {
+
+template <typename T>
+using JsonDataAdder =
+    std::function<void(const folly::fbvector<T>& values, int64_t offset)>;
+
+using JsonErrorRecorder = std::function<void(const Json& json,
+                                             const std::string& nested_path,
+                                             simdjson::error_code error)>;
+
+using JsonNullAdder = std::function<void(int64_t offset)>;
+
+// A helper function for processing json data for building inverted index
+template <typename T>
+void
+ProcessJsonFieldData(
+    const std::vector<std::shared_ptr<FieldDataBase>>& field_datas,
+    const proto::schema::FieldSchema& schema,
+    const std::string& nested_path,
+    const JsonCastType& cast_type,
+    JsonCastFunction cast_function,
+    JsonDataAdder<T> data_adder,
+    JsonNullAdder null_adder,
+    JsonErrorRecorder error_recorder);
+
+extern template void
+ProcessJsonFieldData<bool>(
+    const std::vector<std::shared_ptr<FieldDataBase>>& field_datas,
+    const proto::schema::FieldSchema& schema,
+    const std::string& nested_path,
+    const JsonCastType& cast_type,
+    JsonCastFunction cast_function,
+    JsonDataAdder<bool> data_adder,
+    JsonNullAdder null_adder,
+    JsonErrorRecorder error_recorder);
+
+extern template void
+ProcessJsonFieldData<int64_t>(
+    const std::vector<std::shared_ptr<FieldDataBase>>& field_datas,
+    const proto::schema::FieldSchema& schema,
+    const std::string& nested_path,
+    const JsonCastType& cast_type,
+    JsonCastFunction cast_function,
+    JsonDataAdder<int64_t> data_adder,
+    JsonNullAdder null_adder,
+    JsonErrorRecorder error_recorder);
+
+extern template void
+ProcessJsonFieldData<double>(
+    const std::vector<std::shared_ptr<FieldDataBase>>& field_datas,
+    const proto::schema::FieldSchema& schema,
+    const std::string& nested_path,
+    const JsonCastType& cast_type,
+    JsonCastFunction cast_function,
+    JsonDataAdder<double> data_adder,
+    JsonNullAdder null_adder,
+    JsonErrorRecorder error_recorder);
+
+extern template void
+ProcessJsonFieldData<std::string>(
+    const std::vector<std::shared_ptr<FieldDataBase>>& field_datas,
+    const proto::schema::FieldSchema& schema,
+    const std::string& nested_path,
+    const JsonCastType& cast_type,
+    JsonCastFunction cast_function,
+    JsonDataAdder<std::string> data_adder,
+    JsonNullAdder null_adder,
+    JsonErrorRecorder error_recorder);
+
+}  // namespace milvus::index

internal/core/src/index/JsonInvertedIndex.cpp

@@ -21,6 +21,7 @@
 #include "log/Log.h"
 #include "common/JsonUtils.h"
 #include "simdjson/error.h"
+#include "index/JsonIndexBuilder.h"
 
 namespace milvus::index {
 
@@ -42,74 +43,30 @@ template <typename T>
 void
 JsonInvertedIndex<T>::build_index_for_json(
     const std::vector<std::shared_ptr<FieldDataBase>>& field_datas) {
-    int64_t offset = 0;
     LOG_INFO("Start to build json inverted index for field: {}", nested_path_);
-    using SIMDJSON_T =
-        std::conditional_t<std::is_same_v<T, std::string>, std::string_view, T>;
 
-    auto tokens = parse_json_pointer(nested_path_);
-
-    bool is_array = cast_type_.data_type() == JsonCastType::DataType::ARRAY;
-
-    for (const auto& data : field_datas) {
-        auto n = data->get_num_rows();
-        for (int64_t i = 0; i < n; i++) {
-            auto json_column = static_cast<const Json*>(data->RawValue(i));
-            if (this->schema_.nullable() && !data->is_valid(i)) {
-                this->null_offset_.push_back(offset);
-                this->wrapper_->template add_array_data<T>(
-                    nullptr, 0, offset++);
-                continue;
-            }
-
-            auto exists = path_exists(json_column->dom_doc(), tokens);
-            if (!exists || !json_column->exist(nested_path_)) {
-                error_recorder_.Record(
-                    *json_column, nested_path_, simdjson::NO_SUCH_FIELD);
-                this->null_offset_.push_back(offset);
-                this->wrapper_->template add_array_data<T>(
-                    nullptr, 0, offset++);
-                continue;
-            }
-            folly::fbvector<T> values;
-            if (is_array) {
-                auto doc = json_column->dom_doc();
-                auto array_res = doc.at_pointer(nested_path_).get_array();
-                if (array_res.error() != simdjson::SUCCESS) {
-                    error_recorder_.Record(
-                        *json_column, nested_path_, array_res.error());
-                } else {
-                    auto array_values = array_res.value();
-                    for (auto value : array_values) {
-                        auto val = value.template get<SIMDJSON_T>();
-
-                        if (val.error() == simdjson::SUCCESS) {
-                            values.push_back(static_cast<T>(val.value()));
-                        }
-                    }
-                }
-            } else {
-                if (cast_function_.match<T>()) {
-                    auto res = JsonCastFunction::CastJsonValue<T>(
-                        cast_function_, *json_column, nested_path_);
-                    if (res.has_value()) {
-                        values.push_back(res.value());
-                    }
-                } else {
-                    value_result<SIMDJSON_T> res =
-                        json_column->at<SIMDJSON_T>(nested_path_);
-                    if (res.error() != simdjson::SUCCESS) {
-                        error_recorder_.Record(
-                            *json_column, nested_path_, res.error());
-                    } else {
-                        values.push_back(static_cast<T>(res.value()));
-                    }
-                }
-            }
+    ProcessJsonFieldData<T>(
+        field_datas,
+        this->schema_,
+        nested_path_,
+        cast_type_,
+        cast_function_,
+        // add data
+        [this](const folly::fbvector<T>& values, int64_t offset) {
             this->wrapper_->template add_array_data<T>(
-                values.data(), values.size(), offset++);
-        }
-    }
+                values.data(), values.size(), offset);
+        },
+        // handle null
+        [this](int64_t offset) {
+            this->null_offset_.push_back(offset);
+            this->wrapper_->template add_array_data<T>(nullptr, 0, offset);
+        },
+        // handle error
+        [this](const Json& json,
+               const std::string& nested_path,
+               simdjson::error_code error) {
+            this->error_recorder_.Record(json, nested_path, error);
+        });
 
     error_recorder_.PrintErrStats();
 }

internal/core/src/index/NgramInvertedIndex.cpp

@@ -11,8 +11,16 @@
 
 #include "index/NgramInvertedIndex.h"
 #include "exec/expression/Expr.h"
+#include "index/JsonIndexBuilder.h"
 
 namespace milvus::index {
+
+const JsonCastType JSON_CAST_TYPE = JsonCastType::FromString("VARCHAR");
+// ngram index doesn't need cast function
+const JsonCastFunction JSON_CAST_FUNCTION =
+    JsonCastFunction::FromString("unknown");
+
+// for string/varchar type
 NgramInvertedIndex::NgramInvertedIndex(const storage::FileManagerContext& ctx,
                                        const NgramParams& params)
     : min_gram_(params.min_gram), max_gram_(params.max_gram) {
@@ -34,14 +42,69 @@ NgramInvertedIndex::NgramInvertedIndex(const storage::FileManagerContext& ctx,
     }
 }
 
+// for json type
+NgramInvertedIndex::NgramInvertedIndex(const storage::FileManagerContext& ctx,
+                                       const NgramParams& params,
+                                       const std::string& nested_path)
+    : NgramInvertedIndex(ctx, params) {
+    nested_path_ = nested_path;
+}
+
 void
 NgramInvertedIndex::BuildWithFieldData(const std::vector<FieldDataPtr>& datas) {
     AssertInfo(schema_.data_type() == proto::schema::DataType::String ||
-                   schema_.data_type() == proto::schema::DataType::VarChar,
+                   schema_.data_type() == proto::schema::DataType::VarChar ||
+                   schema_.data_type() == proto::schema::DataType::JSON,
                "schema data type is {}",
                schema_.data_type());
+    LOG_INFO("Start to build ngram index, data type {}, field id: {}",
+             schema_.data_type(),
+             field_id_);
+
     index_build_begin_ = std::chrono::system_clock::now();
-    InvertedIndexTantivy<std::string>::BuildWithFieldData(datas);
+    if (schema_.data_type() == proto::schema::DataType::JSON) {
+        BuildWithJsonFieldData(datas);
+    } else {
+        InvertedIndexTantivy<std::string>::BuildWithFieldData(datas);
+    }
+}
+
+void
+NgramInvertedIndex::BuildWithJsonFieldData(
+    const std::vector<FieldDataPtr>& field_datas) {
+    AssertInfo(schema_.data_type() == proto::schema::DataType::JSON,
+               "schema data should be json, but is {}",
+               schema_.data_type());
+    LOG_INFO("Start to build ngram index for json, field_id: {}, field: {}",
+             field_id_,
+             nested_path_);
+
+    index_build_begin_ = std::chrono::system_clock::now();
+    ProcessJsonFieldData<std::string>(
+        field_datas,
+        this->schema_,
+        nested_path_,
+        JSON_CAST_TYPE,
+        JSON_CAST_FUNCTION,
+        // add data
+        [this](const folly::fbvector<std::string>& values, int64_t offset) {
+            this->wrapper_->template add_array_data<std::string>(
+                values.data(), values.size(), offset);
+        },
+        // handle null
+        [this](int64_t offset) {
+            this->null_offset_.push_back(offset);
+            this->wrapper_->template add_array_data<std::string>(
+                nullptr, 0, offset);
+        },
+        // handle error
+        [this](const Json& json,
+               const std::string& nested_path,
+               simdjson::error_code error) {
+            this->error_recorder_.Record(json, nested_path, error);
+        });
+
+    error_recorder_.PrintErrStats();
 }
 
 IndexStatsPtr
@@ -51,9 +114,12 @@ NgramInvertedIndex::Upload(const Config& config) {
     auto index_build_duration =
         std::chrono::duration<double>(index_build_end - index_build_begin_)
             .count();
-    LOG_INFO("index build done for ngram index, field id: {}, duration: {}s",
-             field_id_,
-             index_build_duration);
+    LOG_INFO(
+        "index build done for ngram index, data type {}, field id: {}, "
+        "duration: {}s",
+        schema_.data_type(),
+        field_id_,
+        index_build_duration);
     return InvertedIndexTantivy<std::string>::Upload(config);
 }
 
@@ -116,30 +182,88 @@ NgramInvertedIndex::ExecuteQuery(const std::string& literal,
     }
 
     switch (op_type) {
-        case proto::plan::OpType::InnerMatch: {
-            auto predicate = [&literal](const std::string_view& data) {
-                return data.find(literal) != std::string::npos;
-            };
-            bool need_post_filter = literal.length() > max_gram_;
-            return ExecuteQueryWithPredicate(
-                literal, segment, predicate, need_post_filter);
-        }
         case proto::plan::OpType::Match:
             return MatchQuery(literal, segment);
+        case proto::plan::OpType::InnerMatch: {
+            bool need_post_filter = literal.length() > max_gram_;
+
+            if (schema_.data_type() == proto::schema::DataType::JSON) {
+                auto predicate = [&literal, this](const milvus::Json& data) {
+                    auto x =
+                        data.template at<std::string_view>(this->nested_path_);
+                    if (x.error()) {
+                        return false;
+                    }
+                    auto data_val = x.value();
+                    return data_val.find(literal) != std::string::npos;
+                };
+
+                return ExecuteQueryWithPredicate<milvus::Json>(
+                    literal, segment, predicate, need_post_filter);
+            } else {
+                auto predicate = [&literal](const std::string_view& data) {
+                    return data.find(literal) != std::string::npos;
+                };
+
+                return ExecuteQueryWithPredicate<std::string_view>(
+                    literal, segment, predicate, need_post_filter);
+            }
+        }
         case proto::plan::OpType::PrefixMatch: {
-            auto predicate = [&literal](const std::string_view& data) {
-                return data.length() >= literal.length() &&
-                       std::equal(literal.begin(), literal.end(), data.begin());
-            };
-            return ExecuteQueryWithPredicate(literal, segment, predicate, true);
+            if (schema_.data_type() == proto::schema::DataType::JSON) {
+                auto predicate = [&literal, this](const milvus::Json& data) {
+                    auto x =
+                        data.template at<std::string_view>(this->nested_path_);
+                    if (x.error()) {
+                        return false;
+                    }
+                    auto data_val = x.value();
+                    return data_val.length() >= literal.length() &&
+                           std::equal(literal.begin(),
+                                      literal.end(),
+                                      data_val.begin());
+                };
+
+                return ExecuteQueryWithPredicate<milvus::Json>(
+                    literal, segment, predicate, true);
+            } else {
+                auto predicate = [&literal](const std::string_view& data) {
+                    return data.length() >= literal.length() &&
+                           std::equal(
+                               literal.begin(), literal.end(), data.begin());
+                };
+
+                return ExecuteQueryWithPredicate<std::string_view>(
+                    literal, segment, predicate, true);
+            }
         }
         case proto::plan::OpType::PostfixMatch: {
-            auto predicate = [&literal](const std::string_view& data) {
-                return data.length() >= literal.length() &&
-                       std::equal(
-                           literal.rbegin(), literal.rend(), data.rbegin());
-            };
-            return ExecuteQueryWithPredicate(literal, segment, predicate, true);
+            if (schema_.data_type() == proto::schema::DataType::JSON) {
+                auto predicate = [&literal, this](const milvus::Json& data) {
+                    auto x =
+                        data.template at<std::string_view>(this->nested_path_);
+                    if (x.error()) {
+                        return false;
+                    }
+                    auto data_val = x.value();
+                    return data_val.length() >= literal.length() &&
+                           std::equal(literal.rbegin(),
+                                      literal.rend(),
+                                      data_val.rbegin());
+                };
+
+                return ExecuteQueryWithPredicate<milvus::Json>(
+                    literal, segment, predicate, true);
+            } else {
+                auto predicate = [&literal](const std::string_view& data) {
+                    return data.length() >= literal.length() &&
+                           std::equal(
+                               literal.rbegin(), literal.rend(), data.rbegin());
+                };
+
+                return ExecuteQueryWithPredicate<std::string_view>(
+                    literal, segment, predicate, true);
+            }
         }
         default:
             LOG_WARN("unsupported op type for ngram index: {}", op_type);
@@ -147,12 +271,12 @@ NgramInvertedIndex::ExecuteQuery(const std::string& literal,
     }
 }
 
+template <typename T>
 inline void
-handle_batch(const std::string_view* data,
-             const int32_t* offsets,
+handle_batch(const T* data,
              const int size,
              TargetBitmapView res,
-             std::function<bool(const std::string_view&)> predicate) {
+             std::function<bool(const T&)> predicate) {
     auto next_off_option = res.find_first();
     while (next_off_option.has_value()) {
         auto next_off = next_off_option.value();
@@ -166,34 +290,35 @@ handle_batch(const std::string_view* data,
     }
 }
 
+template <typename T>
 std::optional<TargetBitmap>
 NgramInvertedIndex::ExecuteQueryWithPredicate(
     const std::string& literal,
     exec::SegmentExpr* segment,
-    std::function<bool(const std::string_view&)> predicate,
+    std::function<bool(const T&)> predicate,
     bool need_post_filter) {
     TargetBitmap bitset{static_cast<size_t>(Count())};
     wrapper_->ngram_match_query(literal, min_gram_, max_gram_, &bitset);
 
-    TargetBitmapView res(bitset);
-    TargetBitmap valid(res.size(), true);
-    TargetBitmapView valid_res(valid.data(), valid.size());
-
     if (need_post_filter) {
+        TargetBitmapView res(bitset);
+        TargetBitmap valid(res.size(), true);
+        TargetBitmapView valid_res(valid.data(), valid.size());
+
         auto execute_batch =
             [&predicate](
-                const std::string_view* data,
+                const T* data,
                 // `valid_data` is not used as the results returned  by ngram_match_query are all valid
                 const bool* _valid_data,
-                const int32_t* offsets,
+                const int32_t* _offsets,
                 const int size,
                 TargetBitmapView res,
                 // the same with `valid_data`
                 TargetBitmapView _valid_res) {
-                handle_batch(data, offsets, size, res, predicate);
+                handle_batch(data, size, res, predicate);
             };
 
-        segment->ProcessAllDataChunk<std::string_view>(
+        segment->ProcessAllDataChunk<T>(
             execute_batch, std::nullptr_t{}, res, valid_res);
     }
 
@@ -250,24 +375,52 @@ NgramInvertedIndex::MatchQuery(const std::string& literal,
     auto regex_pattern = translator(literal);
     RegexMatcher matcher(regex_pattern);
 
-    auto predicate = [&matcher](const std::string_view& data) {
-        return matcher(data);
-    };
-
-    auto execute_batch =
-        [&predicate](
-            const std::string_view* data,
-            // `_valid_data` is not used as the results returned  by ngram_match_query are all valid
-            const bool* _valid_data,
-            const int32_t* offsets,
-            const int size,
-            TargetBitmapView res,
-            // the same with `_valid_data`
-            TargetBitmapView _valid_res) {
-            handle_batch(data, offsets, size, res, predicate);
+    if (schema_.data_type() == proto::schema::DataType::JSON) {
+        auto predicate = [&literal, &matcher, this](const milvus::Json& data) {
+            auto x = data.template at<std::string_view>(this->nested_path_);
+            if (x.error()) {
+                return false;
+            }
+            auto data_val = x.value();
+            return matcher(data_val);
         };
-    segment->ProcessAllDataChunk<std::string_view>(
-        execute_batch, std::nullptr_t{}, res, valid_res);
+
+        auto execute_batch_json =
+            [&predicate](
+                const milvus::Json* data,
+                // `valid_data` is not used as the results returned  by ngram_match_query are all valid
+                const bool* _valid_data,
+                const int32_t* _offsets,
+                const int size,
+                TargetBitmapView res,
+                // the same with `valid_data`
+                TargetBitmapView _valid_res,
+                std::string val) {
+                handle_batch<milvus::Json>(data, size, res, predicate);
+            };
+
+        segment->ProcessAllDataChunk<milvus::Json>(
+            execute_batch_json, std::nullptr_t{}, res, valid_res, literal);
+    } else {
+        auto predicate = [&matcher](const std::string_view& data) {
+            return matcher(data);
+        };
+
+        auto execute_batch =
+            [&predicate](
+                const std::string_view* data,
+                // `valid_data` is not used as the results returned  by ngram_match_query are all valid
+                const bool* _valid_data,
+                const int32_t* _offsets,
+                const int size,
+                TargetBitmapView res,
+                // the same with `valid_data`
+                TargetBitmapView _valid_res) {
+                handle_batch<std::string_view>(data, size, res, predicate);
+            };
+        segment->ProcessAllDataChunk<std::string_view>(
+            execute_batch, std::nullptr_t{}, res, valid_res);
+    }
 
     return std::optional<TargetBitmap>(std::move(bitset));
 }

internal/core/src/index/NgramInvertedIndex.h

@@ -13,7 +13,7 @@
 #include <string>
 #include <boost/filesystem.hpp>
 #include <optional>
-
+#include "index/JsonInvertedIndex.h"
 #include "index/InvertedIndexTantivy.h"
 
 namespace milvus::exec {
@@ -23,9 +23,15 @@ class SegmentExpr;
 namespace milvus::index {
 class NgramInvertedIndex : public InvertedIndexTantivy<std::string> {
  public:
+    // for string/varchar type
     explicit NgramInvertedIndex(const storage::FileManagerContext& ctx,
                                 const NgramParams& params);
 
+    // for json type
+    explicit NgramInvertedIndex(const storage::FileManagerContext& ctx,
+                                const NgramParams& params,
+                                const std::string& nested_path);
+
     IndexStatsPtr
     Upload(const Config& config = {}) override;
 
@@ -35,18 +41,31 @@ class NgramInvertedIndex : public InvertedIndexTantivy<std::string> {
     void
     BuildWithFieldData(const std::vector<FieldDataPtr>& datas) override;
 
+    void
+    BuildWithJsonFieldData(const std::vector<FieldDataPtr>& datas);
+
     std::optional<TargetBitmap>
     ExecuteQuery(const std::string& literal,
                  proto::plan::OpType op_type,
                  exec::SegmentExpr* segment);
 
+    void
+    finish() {
+        this->wrapper_->finish();
+    }
+
+    void
+    create_reader(SetBitsetFn set_bitset) {
+        this->wrapper_->create_reader(set_bitset);
+    }
+
  private:
+    template <typename T>
     std::optional<TargetBitmap>
-    ExecuteQueryWithPredicate(
-        const std::string& literal,
-        exec::SegmentExpr* segment,
-        std::function<bool(const std::string_view&)> predicate,
-        bool need_post_filter);
+    ExecuteQueryWithPredicate(const std::string& literal,
+                              exec::SegmentExpr* segment,
+                              std::function<bool(const T&)> predicate,
+                              bool need_post_filter);
 
     // Match is something like xxx%xxx%xxx, xxx%xxx, %xxx%xxx, xxx_x etc.
     std::optional<TargetBitmap>
@@ -57,5 +76,9 @@ class NgramInvertedIndex : public InvertedIndexTantivy<std::string> {
     uintptr_t max_gram_{0};
     int64_t field_id_{0};
     std::chrono::time_point<std::chrono::system_clock> index_build_begin_;
+
+    // for json type
+    std::string nested_path_;
+    JsonInvertedIndexParseErrorRecorder error_recorder_;
 };
 }  // namespace milvus::index

internal/core/src/segcore/ChunkedSegmentSealedImpl.cpp

@@ -172,14 +172,27 @@ ChunkedSegmentSealedImpl::LoadScalarIndex(const LoadIndexInfo& info) {
 
     if (field_meta.get_data_type() == DataType::JSON) {
         auto path = info.index_params.at(JSON_PATH);
-        JsonIndex index;
-        index.nested_path = path;
-        index.field_id = field_id;
-        index.index = std::move(const_cast<LoadIndexInfo&>(info).cache_index);
-        index.cast_type =
-            JsonCastType::FromString(info.index_params.at(JSON_CAST_TYPE));
-        json_indices.push_back(std::move(index));
-        return;
+        if (auto it = info.index_params.find(index::INDEX_TYPE);
+            it != info.index_params.end() &&
+            it->second == index::NGRAM_INDEX_TYPE) {
+            if (ngram_indexings_.find(field_id) == ngram_indexings_.end()) {
+                ngram_indexings_[field_id] =
+                    std::unordered_map<std::string, index::CacheIndexBasePtr>();
+            }
+            ngram_indexings_[field_id][path] =
+                std::move(const_cast<LoadIndexInfo&>(info).cache_index);
+            return;
+        } else {
+            JsonIndex index;
+            index.nested_path = path;
+            index.field_id = field_id;
+            index.index =
+                std::move(const_cast<LoadIndexInfo&>(info).cache_index);
+            index.cast_type =
+                JsonCastType::FromString(info.index_params.at(JSON_CAST_TYPE));
+            json_indices.push_back(std::move(index));
+            return;
+        }
     }
 
     if (auto it = info.index_params.find(index::INDEX_TYPE);
@@ -637,6 +650,29 @@ ChunkedSegmentSealedImpl::GetNgramIndex(FieldId field_id) const {
     return PinWrapper<index::NgramInvertedIndex*>(ca, index);
 }
 
+PinWrapper<index::NgramInvertedIndex*>
+ChunkedSegmentSealedImpl::GetNgramIndexForJson(
+    FieldId field_id, const std::string& nested_path) const {
+    std::shared_lock lck(mutex_);
+    auto iter = ngram_indexings_.find(field_id);
+    if (iter == ngram_indexings_.end() ||
+        iter->second.find(nested_path) == iter->second.end()) {
+        return PinWrapper<index::NgramInvertedIndex*>(nullptr);
+    }
+
+    auto slot = iter->second.at(nested_path).get();
+    lck.unlock();
+
+    auto ca = SemiInlineGet(slot->PinCells({0}));
+    auto index = dynamic_cast<index::NgramInvertedIndex*>(ca->get_cell_of(0));
+    AssertInfo(index != nullptr,
+               "ngram index cache for json is corrupted, field_id: {}, "
+               "nested_path: {}",
+               field_id.get(),
+               nested_path);
+    return PinWrapper<index::NgramInvertedIndex*>(ca, index);
+}
+
 int64_t
 ChunkedSegmentSealedImpl::get_row_count() const {
     std::shared_lock lck(mutex_);
@@ -1127,6 +1163,7 @@ ChunkedSegmentSealedImpl::ClearData() {
         ngram_fields_.clear();
         scalar_indexings_.clear();
         vector_indexings_.clear();
+        ngram_indexings_.clear();
         insert_record_.clear();
         fields_.clear();
         variable_fields_avg_size_.clear();

internal/core/src/segcore/ChunkedSegmentSealedImpl.h

@@ -123,9 +123,22 @@ class ChunkedSegmentSealedImpl : public SegmentSealed {
         return ngram_fields_.find(field_id) != ngram_fields_.end();
     }
 
+    bool
+    HasNgramIndexForJson(FieldId field_id,
+                         const std::string& nested_path) const override {
+        std::shared_lock lck(mutex_);
+        return ngram_indexings_.find(field_id) != ngram_indexings_.end() &&
+               ngram_indexings_.at(field_id).find(nested_path) !=
+                   ngram_indexings_.at(field_id).end();
+    }
+
     PinWrapper<index::NgramInvertedIndex*>
     GetNgramIndex(FieldId field_id) const override;
 
+    PinWrapper<index::NgramInvertedIndex*>
+    GetNgramIndexForJson(FieldId field_id,
+                         const std::string& nested_path) const override;
+
     // TODO(tiered storage 1): should return a PinWrapper
     void
     BulkGetJsonData(FieldId field_id,
@@ -432,6 +445,12 @@ class ChunkedSegmentSealedImpl : public SegmentSealed {
     // TODO: generate index for scalar
     std::optional<int64_t> num_rows_;
 
+    // ngram indexings for json type
+    std::unordered_map<
+        FieldId,
+        std::unordered_map<std::string, index::CacheIndexBasePtr>>
+        ngram_indexings_;
+
     // fields that has ngram index
     std::unordered_set<FieldId> ngram_fields_{};
 

internal/core/src/segcore/SegmentInterface.cpp

@@ -542,4 +542,21 @@ SegmentInternalInterface::GetNgramIndex(FieldId field_id) const {
     return PinWrapper<index::NgramInvertedIndex*>(nullptr);
 }
 
+PinWrapper<index::NgramInvertedIndex*>
+SegmentInternalInterface::GetNgramIndexForJson(
+    FieldId field_id, const std::string& nested_path) const {
+    return PinWrapper<index::NgramInvertedIndex*>(nullptr);
+}
+
+bool
+SegmentInternalInterface::HasNgramIndex(FieldId field_id) const {
+    return false;
+}
+
+bool
+SegmentInternalInterface::HasNgramIndexForJson(
+    FieldId field_id, const std::string& nested_path) const {
+    return false;
+}
+
 }  // namespace milvus::segcore

internal/core/src/segcore/SegmentInterface.h

@@ -155,6 +155,17 @@ class SegmentInterface {
     virtual PinWrapper<index::NgramInvertedIndex*>
     GetNgramIndex(FieldId field_id) const = 0;
 
+    virtual PinWrapper<index::NgramInvertedIndex*>
+    GetNgramIndexForJson(FieldId field_id,
+                         const std::string& nested_path) const = 0;
+
+    virtual bool
+    HasNgramIndex(FieldId field_id) const = 0;
+
+    virtual bool
+    HasNgramIndexForJson(FieldId field_id,
+                         const std::string& nested_path) const = 0;
+
     virtual void
     LazyCheckSchema(SchemaPtr sch) = 0;
 
@@ -369,6 +380,17 @@ class SegmentInternalInterface : public SegmentInterface {
     virtual PinWrapper<index::NgramInvertedIndex*>
     GetNgramIndex(FieldId field_id) const override;
 
+    virtual PinWrapper<index::NgramInvertedIndex*>
+    GetNgramIndexForJson(FieldId field_id,
+                         const std::string& nested_path) const override;
+
+    virtual bool
+    HasNgramIndex(FieldId field_id) const override;
+
+    virtual bool
+    HasNgramIndexForJson(FieldId field_id,
+                         const std::string& nested_path) const override;
+
  public:
     virtual void
     vector_search(SearchInfo& search_info,

internal/core/src/segcore/SegmentSealed.h

@@ -107,9 +107,17 @@ class SegmentSealed : public SegmentInternalInterface {
     virtual bool
     HasNgramIndex(FieldId field_id) const = 0;
 
+    virtual bool
+    HasNgramIndexForJson(FieldId field_id,
+                         const std::string& nested_path) const = 0;
+
     virtual PinWrapper<index::NgramInvertedIndex*>
     GetNgramIndex(FieldId field_id) const override = 0;
 
+    virtual PinWrapper<index::NgramInvertedIndex*>
+    GetNgramIndexForJson(FieldId field_id,
+                         const std::string& nested_path) const override = 0;
+
     SegmentType
     type() const override {
         return SegmentType::Sealed;

internal/core/unittest/test_expr.cpp

@@ -16530,9 +16530,11 @@ TYPED_TEST(JsonIndexTestFixture, TestJsonIndexUnaryExpr) {
     file_manager_ctx.fieldDataMeta.field_schema.set_fieldid(json_fid.get());
     file_manager_ctx.fieldDataMeta.field_id = json_fid.get();
     auto inv_index = index::IndexFactory::GetInstance().CreateJsonIndex(
-        index::INVERTED_INDEX_TYPE,
-        this->cast_type,
-        this->json_path,
+        index::CreateIndexInfo{
+            .index_type = index::INVERTED_INDEX_TYPE,
+            .json_cast_type = this->cast_type,
+            .json_path = this->json_path,
+        },
         file_manager_ctx);
 
     using json_index_type =
@@ -16664,10 +16666,13 @@ TEST(JsonIndexTest, TestJsonNotEqualExpr) {
     file_manager_ctx.fieldDataMeta.field_schema.set_data_type(
         milvus::proto::schema::JSON);
     file_manager_ctx.fieldDataMeta.field_schema.set_fieldid(json_fid.get());
+
     auto inv_index = index::IndexFactory::GetInstance().CreateJsonIndex(
-        index::INVERTED_INDEX_TYPE,
-        JsonCastType::FromString("DOUBLE"),
-        "/a",
+        index::CreateIndexInfo{
+            .index_type = index::INVERTED_INDEX_TYPE,
+            .json_cast_type = JsonCastType::FromString("DOUBLE"),
+            .json_path = "/a",
+        },
         file_manager_ctx);
 
     using json_index_type = index::JsonInvertedIndex<double>;
@@ -16772,9 +16777,11 @@ TEST_P(JsonIndexExistsTest, TestExistsExpr) {
     file_manager_ctx.fieldDataMeta.field_schema.set_fieldid(json_fid.get());
     file_manager_ctx.fieldDataMeta.field_schema.set_nullable(true);
     auto inv_index = index::IndexFactory::GetInstance().CreateJsonIndex(
-        index::INVERTED_INDEX_TYPE,
-        JsonCastType::FromString("DOUBLE"),
-        json_index_path,
+        index::CreateIndexInfo{
+            .index_type = index::INVERTED_INDEX_TYPE,
+            .json_cast_type = JsonCastType::FromString("DOUBLE"),
+            .json_path = json_index_path,
+        },
         file_manager_ctx);
 
     using json_index_type = index::JsonInvertedIndex<double>;
@@ -16958,7 +16965,12 @@ TEST_P(JsonIndexBinaryExprTest, TestBinaryRangeExpr) {
     file_manager_ctx.fieldDataMeta.field_schema.set_fieldid(json_fid.get());
 
     auto inv_index = index::IndexFactory::GetInstance().CreateJsonIndex(
-        index::INVERTED_INDEX_TYPE, GetParam(), "/a", file_manager_ctx);
+        index::CreateIndexInfo{
+            .index_type = index::INVERTED_INDEX_TYPE,
+            .json_cast_type = GetParam(),
+            .json_path = "/a",
+        },
+        file_manager_ctx);
 
     using json_index_type = index::JsonInvertedIndex<double>;
     auto json_index = std::unique_ptr<json_index_type>(

internal/core/unittest/test_json_flat_index.cpp

@@ -609,9 +609,11 @@ class JsonFlatIndexExprTest : public ::testing::Test {
             json_fid_.get());
         file_manager_ctx.fieldDataMeta.field_schema.set_nullable(true);
         auto index = index::IndexFactory::GetInstance().CreateJsonIndex(
-            index::INVERTED_INDEX_TYPE,
-            JsonCastType::FromString("JSON"),
-            json_index_path,
+            index::CreateIndexInfo{
+                .index_type = index::INVERTED_INDEX_TYPE,
+                .json_cast_type = JsonCastType::FromString("JSON"),
+                .json_path = json_index_path,
+            },
             file_manager_ctx);
 
         json_index_ = std::unique_ptr<index::JsonFlatIndex>(

internal/core/unittest/test_json_index.cpp

@@ -57,9 +57,11 @@ TEST(JsonIndexTest, TestJSONErrRecorder) {
     file_manager_ctx.fieldDataMeta.field_id = json_fid.get();
 
     auto inv_index = index::IndexFactory::GetInstance().CreateJsonIndex(
-        index::INVERTED_INDEX_TYPE,
-        JsonCastType::FromString("DOUBLE"),
-        json_path,
+        index::CreateIndexInfo{
+            .index_type = index::INVERTED_INDEX_TYPE,
+            .json_cast_type = JsonCastType::FromString("DOUBLE"),
+            .json_path = json_path,
+        },
         file_manager_ctx);
     auto json_index = std::unique_ptr<JsonInvertedIndex<double>>(
         static_cast<JsonInvertedIndex<double>*>(inv_index.release()));
@@ -118,9 +120,11 @@ TEST(JsonIndexTest, TestJsonContains) {
     file_manager_ctx.fieldDataMeta.field_id = json_fid.get();
 
     auto inv_index = index::IndexFactory::GetInstance().CreateJsonIndex(
-        index::INVERTED_INDEX_TYPE,
-        JsonCastType::FromString("ARRAY_DOUBLE"),
-        json_path,
+        index::CreateIndexInfo{
+            .index_type = index::INVERTED_INDEX_TYPE,
+            .json_cast_type = JsonCastType::FromString("ARRAY_DOUBLE"),
+            .json_path = json_path,
+        },
         file_manager_ctx);
     auto json_index = std::unique_ptr<JsonInvertedIndex<double>>(
         static_cast<JsonInvertedIndex<double>*>(inv_index.release()));
@@ -212,11 +216,13 @@ TEST(JsonIndexTest, TestJsonCast) {
     file_manager_ctx.fieldDataMeta.field_id = json_fid.get();
 
     auto inv_index = index::IndexFactory::GetInstance().CreateJsonIndex(
-        index::INVERTED_INDEX_TYPE,
-        JsonCastType::FromString("DOUBLE"),
-        json_path,
-        file_manager_ctx,
-        "STRING_TO_DOUBLE");
+        index::CreateIndexInfo{
+            .index_type = index::INVERTED_INDEX_TYPE,
+            .json_cast_type = JsonCastType::FromString("DOUBLE"),
+            .json_path = json_path,
+            .json_cast_function = "STRING_TO_DOUBLE",
+        },
+        file_manager_ctx);
     auto json_index = std::unique_ptr<JsonInvertedIndex<double>>(
         static_cast<JsonInvertedIndex<double>*>(inv_index.release()));
 

internal/core/unittest/test_ngram_query.cpp

@@ -22,6 +22,8 @@
 #include "index/IndexFactory.h"
 #include "index/NgramInvertedIndex.h"
 #include "segcore/load_index_c.h"
+#include "test_cachinglayer/cachinglayer_test_utils.h"
+#include "expr/ITypeExpr.h"
 
 using namespace milvus;
 using namespace milvus::query;
@@ -381,3 +383,137 @@ TEST(NgramIndex, TestNgramSimple) {
                          proto::plan::OpType::PostfixMatch,
                          std::vector<bool>(10000, true));
 }
+
+TEST(NgramIndex, TestNgramJson) {
+    std::vector<std::string> json_raw_data = {
+        R"(1)",
+        R"({"a": "Milvus project"})",
+        R"({"a": "Zilliz cloud"})",
+        R"({"a": "Query Node"})",
+        R"({"a": "Data Node"})",
+        R"({"a": [1, 2, 3]})",
+        R"({"a": {"b": 1}})",
+        R"({"a": 1001})",
+        R"({"a": true})",
+        R"({"a": "Milvus", "b": "Zilliz cloud"})",
+    };
+
+    auto json_path = "/a";
+    auto schema = std::make_shared<Schema>();
+    auto json_fid = schema->AddDebugField("json", DataType::JSON);
+
+    auto file_manager_ctx = storage::FileManagerContext();
+    file_manager_ctx.fieldDataMeta.field_schema.set_data_type(
+        milvus::proto::schema::JSON);
+    file_manager_ctx.fieldDataMeta.field_schema.set_fieldid(json_fid.get());
+    file_manager_ctx.fieldDataMeta.field_id = json_fid.get();
+
+    index::CreateIndexInfo create_index_info{
+        .index_type = index::INVERTED_INDEX_TYPE,
+        .json_cast_type = JsonCastType::FromString("VARCHAR"),
+        .json_path = json_path,
+        .ngram_params = std::optional<index::NgramParams>{index::NgramParams{
+            .loading_index = false,
+            .min_gram = 2,
+            .max_gram = 3,
+        }},
+    };
+    auto inv_index = index::IndexFactory::GetInstance().CreateJsonIndex(
+        create_index_info, file_manager_ctx);
+
+    auto ngram_index = std::unique_ptr<index::NgramInvertedIndex>(
+        static_cast<index::NgramInvertedIndex*>(inv_index.release()));
+
+    std::vector<milvus::Json> jsons;
+    for (auto& json : json_raw_data) {
+        jsons.push_back(milvus::Json(simdjson::padded_string(json)));
+    }
+
+    auto json_field =
+        std::make_shared<FieldData<milvus::Json>>(DataType::JSON, false);
+    json_field->add_json_data(jsons);
+    ngram_index->BuildWithFieldData({json_field});
+    ngram_index->finish();
+    ngram_index->create_reader(milvus::index::SetBitsetSealed);
+
+    auto segment = segcore::CreateSealedSegment(schema);
+    segcore::LoadIndexInfo load_index_info;
+    load_index_info.field_id = json_fid.get();
+    load_index_info.field_type = DataType::JSON;
+    load_index_info.cache_index =
+        CreateTestCacheIndex("", std::move(ngram_index));
+
+    std::map<std::string, std::string> index_params{
+        {milvus::index::INDEX_TYPE, milvus::index::NGRAM_INDEX_TYPE},
+        {milvus::index::MIN_GRAM, "2"},
+        {milvus::index::MAX_GRAM, "3"},
+        {milvus::LOAD_PRIORITY, "HIGH"},
+        {JSON_PATH, json_path},
+        {JSON_CAST_TYPE, "VARCHAR"}};
+    load_index_info.index_params = index_params;
+
+    segment->LoadIndex(load_index_info);
+
+    auto cm = milvus::storage::RemoteChunkManagerSingleton::GetInstance()
+                  .GetRemoteChunkManager();
+    auto load_info = PrepareSingleFieldInsertBinlog(
+        0, 0, 0, json_fid.get(), {json_field}, cm);
+    segment->LoadFieldData(load_info);
+
+    std::vector<std::tuple<proto::plan::GenericValue,
+                           std::vector<int64_t>,
+                           proto::plan::OpType>>
+        test_cases;
+    proto::plan::GenericValue value;
+    value.set_string_val("nothing");
+    test_cases.push_back(std::make_tuple(
+        value, std::vector<int64_t>{}, proto::plan::OpType::InnerMatch));
+
+    value.set_string_val("il");
+    test_cases.push_back(std::make_tuple(
+        value, std::vector<int64_t>{1, 2, 9}, proto::plan::OpType::InnerMatch));
+
+    value.set_string_val("lliz");
+    test_cases.push_back(std::make_tuple(
+        value, std::vector<int64_t>{2}, proto::plan::OpType::InnerMatch));
+
+    value.set_string_val("Zi");
+    test_cases.push_back(std::make_tuple(
+        value, std::vector<int64_t>{2}, proto::plan::OpType::PrefixMatch));
+
+    value.set_string_val("Zilliz");
+    test_cases.push_back(std::make_tuple(
+        value, std::vector<int64_t>{2}, proto::plan::OpType::PrefixMatch));
+
+    value.set_string_val("de");
+    test_cases.push_back(std::make_tuple(
+        value, std::vector<int64_t>{3, 4}, proto::plan::OpType::PostfixMatch));
+
+    value.set_string_val("Node");
+    test_cases.push_back(std::make_tuple(
+        value, std::vector<int64_t>{3, 4}, proto::plan::OpType::PostfixMatch));
+
+    value.set_string_val("%ery%ode%");
+    test_cases.push_back(std::make_tuple(
+        value, std::vector<int64_t>{3}, proto::plan::OpType::Match));
+
+    for (auto& test_case : test_cases) {
+        auto value = std::get<0>(test_case);
+        auto expr = std::make_shared<milvus::expr::UnaryRangeFilterExpr>(
+            milvus::expr::ColumnInfo(json_fid, DataType::JSON, {"a"}, true),
+            std::get<2>(test_case),
+            value,
+            std::vector<proto::plan::GenericValue>{});
+
+        auto plan =
+            std::make_shared<plan::FilterBitsNode>(DEFAULT_PLANNODE_ID, expr);
+
+        auto result = milvus::query::ExecuteQueryExpr(
+            plan, segment.get(), json_raw_data.size(), MAX_TIMESTAMP);
+        auto expect_result = std::get<1>(test_case);
+        EXPECT_EQ(result.count(), expect_result.size());
+        for (auto& id : expect_result) {
+            EXPECT_TRUE(result[id]);
+        }
+    }
+}

internal/util/indexparamcheck/ngram_index_checker.go

@@ -23,9 +23,8 @@ func newNgramIndexChecker() *NgramIndexChecker {
 }
 
 func (c *NgramIndexChecker) CheckTrain(dataType schemapb.DataType, params map[string]string) error {
-	if dataType != schemapb.DataType_VarChar {
-		// todo(SpadeA): we may support it for json in the future
-		return merr.WrapErrParameterInvalidMsg("Ngram index can only be created on VARCHAR field")
+	if dataType != schemapb.DataType_VarChar && dataType != schemapb.DataType_JSON {
+		return merr.WrapErrParameterInvalidMsg("Ngram index can only be created on VARCHAR or JSON field")
 	}
 
 	minGramStr, minGramExist := params[MinGramKey]
@@ -53,8 +52,8 @@ func (c *NgramIndexChecker) CheckTrain(dataType schemapb.DataType, params map[st
 
 func (c *NgramIndexChecker) CheckValidDataType(indexType IndexType, field *schemapb.FieldSchema) error {
 	dType := field.GetDataType()
-	if !typeutil.IsStringType(dType) {
-		return fmt.Errorf("ngram index can only be created on VARCHAR field")
+	if !typeutil.IsStringType(dType) && dType != schemapb.DataType_JSON {
+		return fmt.Errorf("ngram index can only be created on VARCHAR or JSON field")
 	}
 	return nil
 }