diff --git a/core/src/cache/CpuCacheMgr.cpp b/core/src/cache/CpuCacheMgr.cpp
index 6601b48448bdc35b2a5a511bc56d470100ff24d0..b71e59a95050e28b602221f46d330b986b58b161 100644
--- a/core/src/cache/CpuCacheMgr.cpp
+++ b/core/src/cache/CpuCacheMgr.cpp
@@ -38,17 +38,6 @@ CpuCacheMgr::GetInstance() {
     return s_mgr;
 }
 
-DataObjPtr
-CpuCacheMgr::GetDataObj(const std::string& key) {
-    DataObjPtr obj = GetItem(key);
-    return obj;
-}
-
-void
-CpuCacheMgr::SetDataObj(const std::string& key, const milvus::cache::DataObjPtr& data) {
-    CacheMgr<DataObjPtr>::InsertItem(key, data);
-}
-
 void
 CpuCacheMgr::ConfigUpdate(const std::string& name) {
     SetCapacity(config.cache.cache_size());
diff --git a/core/src/cache/CpuCacheMgr.h b/core/src/cache/CpuCacheMgr.h
index c5dd691d2cdbacd98a88686abba53992ad7570ff..455479f41c25c107f8b9308e11dbd3651fefbd92 100644
--- a/core/src/cache/CpuCacheMgr.h
+++ b/core/src/cache/CpuCacheMgr.h
@@ -31,12 +31,6 @@ class CpuCacheMgr : public CacheMgr<DataObjPtr>, public ConfigObserver {
     static CpuCacheMgr&
     GetInstance();
 
-    DataObjPtr
-    GetDataObj(const std::string& key);
-
-    void
-    SetDataObj(const std::string& key, const DataObjPtr& data);
-
  public:
     void
     ConfigUpdate(const std::string& name) override;
diff --git a/core/src/cache/GpuCacheMgr.cpp b/core/src/cache/GpuCacheMgr.cpp
index 305530996108927071c00555b305634b8ea47cb6..f1486a575956692bd09088e3a5b36463a6f24f6c 100644
--- a/core/src/cache/GpuCacheMgr.cpp
+++ b/core/src/cache/GpuCacheMgr.cpp
@@ -51,17 +51,6 @@ GpuCacheMgr::GetInstance(int64_t gpu_id) {
     return instance_[gpu_id];
 }
 
-DataObjPtr
-GpuCacheMgr::GetDataObj(const std::string& key) {
-    DataObjPtr obj = GetItem(key);
-    return obj;
-}
-
-void
-GpuCacheMgr::SetDataObj(const std::string& key, const milvus::cache::DataObjPtr& data) {
-    CacheMgr<DataObjPtr>::InsertItem(key, data);
-}
-
 bool
 GpuCacheMgr::Reserve(const int64_t size) {
     return CacheMgr<DataObjPtr>::Reserve(size);
diff --git a/core/src/cache/GpuCacheMgr.h b/core/src/cache/GpuCacheMgr.h
index b49b4a6bea6845b2812d447134e7784a24d1be44..f2dd4c899bccf1df6bc0868e0824a12edceb3aac 100644
--- a/core/src/cache/GpuCacheMgr.h
+++ b/core/src/cache/GpuCacheMgr.h
@@ -36,12 +36,6 @@ class GpuCacheMgr : public CacheMgr<DataObjPtr>, public ConfigObserver {
     static GpuCacheMgrPtr
     GetInstance(int64_t gpu_id);
 
-    DataObjPtr
-    GetDataObj(const std::string& key);
-
-    void
-    SetDataObj(const std::string& key, const DataObjPtr& data);
-
     bool
     Reserve(const int64_t size);
 
diff --git a/core/src/codecs/DeletedDocsFormat.cpp b/core/src/codecs/DeletedDocsFormat.cpp
index b061f13816f3fc446b00d231b486615a829ed163..7dd772391139b2d581a410d78460a1f87bd25b0d 100644
--- a/core/src/codecs/DeletedDocsFormat.cpp
+++ b/core/src/codecs/DeletedDocsFormat.cpp
@@ -98,7 +98,7 @@ DeletedDocsFormat::Write(const storage::FSHandlerPtr& fs_ptr, const std::string&
     }
 
     auto deleted_docs_list = deleted_docs->GetDeletedDocs();
-    size_t new_num_bytes = old_num_bytes + sizeof(segment::offset_t) * deleted_docs->GetSize();
+    size_t new_num_bytes = old_num_bytes + sizeof(segment::offset_t) * deleted_docs->GetCount();
     if (!deleted_docs_list.empty()) {
         delete_ids.insert(delete_ids.end(), deleted_docs_list.begin(), deleted_docs_list.end());
     }
diff --git a/core/src/db/DBImpl.cpp b/core/src/db/DBImpl.cpp
index b3d00fee095f2595a21fdea5b01e37cf256ae2e1..a5c16f58521dcd0ef675a9c97a7b23acfa891243 100644
--- a/core/src/db/DBImpl.cpp
+++ b/core/src/db/DBImpl.cpp
@@ -516,10 +516,6 @@ DBImpl::Insert(const std::string& collection_name, const std::string& partition_
     }
 
     // generate id
-    DataChunkPtr new_chunk = std::make_shared<DataChunk>();
-    new_chunk->fixed_fields_ = data_chunk->fixed_fields_;
-    new_chunk->variable_fields_ = data_chunk->variable_fields_;
-    new_chunk->count_ = data_chunk->count_;
     if (auto_increment) {
         SafeIDGenerator& id_generator = SafeIDGenerator::GetInstance();
         IDNumbers ids;
@@ -527,7 +523,7 @@ DBImpl::Insert(const std::string& collection_name, const std::string& partition_
         BinaryDataPtr id_data = std::make_shared<BinaryData>();
         id_data->data_.resize(ids.size() * sizeof(int64_t));
         memcpy(id_data->data_.data(), ids.data(), ids.size() * sizeof(int64_t));
-        new_chunk->fixed_fields_[engine::DEFAULT_UID_NAME] = id_data;
+        data_chunk->fixed_fields_[engine::DEFAULT_UID_NAME] = id_data;
     }
 
     if (options_.wal_enable_) {
@@ -549,8 +545,8 @@ DBImpl::Insert(const std::string& collection_name, const std::string& partition_
         record.lsn = 0;
         record.collection_id = collection_name;
         record.partition_tag = partition_name;
-        record.data_chunk = new_chunk;
-        record.length = new_chunk->count_;
+        record.data_chunk = data_chunk;
+        record.length = data_chunk->count_;
         record.type = wal::MXLogType::Entity;
 
         STATUS_CHECK(ExecWalRecord(record));
@@ -614,7 +610,6 @@ DBImpl::Query(const server::ContextPtr& context, const query::QueryPtr& query_pt
 
     snapshot::ScopedSnapshotT ss;
     STATUS_CHECK(snapshot::Snapshots::GetInstance().GetSnapshot(ss, query_ptr->collection_id));
-    auto ss_id = ss->GetID();
 
     /* collect all valid segment */
     std::vector<SegmentVisitor::Ptr> segment_visitors;
@@ -659,9 +654,11 @@ DBImpl::Query(const server::ContextPtr& context, const query::QueryPtr& query_pt
 
     scheduler::SearchJobPtr job = std::make_shared<scheduler::SearchJob>(nullptr, ss, options_, query_ptr, segment_ids);
 
+    cache::CpuCacheMgr::GetInstance().PrintInfo();  // print cache info before query
     /* put search job to scheduler and wait job finish */
     scheduler::JobMgrInst::GetInstance()->Put(job);
     job->WaitFinish();
+    cache::CpuCacheMgr::GetInstance().PrintInfo();  // print cache info after query
 
     if (!job->status().ok()) {
         return job->status();
@@ -858,7 +855,7 @@ DBImpl::Compact(const std::shared_ptr<server::Context>& context, const std::stri
             continue;
         }
 
-        auto deleted_count = deleted_docs->GetSize();
+        auto deleted_count = deleted_docs->GetCount();
         if (deleted_count / (row_count + deleted_count) < threshold) {
             continue;  // no need to compact
         }
diff --git a/core/src/db/SnapshotUtils.cpp b/core/src/db/SnapshotUtils.cpp
index f1e96a658a839388b6d90a9a3e57f1c72c843408..0ab1fbb0d5deda5648b838d7d4f494a51ae5fd19 100644
--- a/core/src/db/SnapshotUtils.cpp
+++ b/core/src/db/SnapshotUtils.cpp
@@ -36,6 +36,7 @@ const char* JSON_FIELD_ELEMENT = "field_element";
 const char* JSON_PARTITION_TAG = "tag";
 const char* JSON_FILES = "files";
 const char* JSON_INDEX_NAME = "index_name";
+const char* JSON_INDEX_TYPE = "index_type";
 const char* JSON_DATA_SIZE = "data_size";
 const char* JSON_PATH = "path";
 
@@ -165,6 +166,7 @@ GetSnapshotInfo(const std::string& collection_name, milvus::json& json_info) {
     size_t total_row_count = 0;
     size_t total_data_size = 0;
 
+    // get partition information
     std::unordered_map<snapshot::ID_TYPE, milvus::json> partitions;
     auto partition_names = ss->GetPartitionNames();
     for (auto& name : partition_names) {
@@ -183,11 +185,13 @@ GetSnapshotInfo(const std::string& collection_name, milvus::json& json_info) {
         partitions.insert(std::make_pair(partition->GetID(), json_partition));
     }
 
+    // just ensure segments listed in id order
     snapshot::IDS_TYPE segment_ids;
     auto handler = std::make_shared<SegmentsToSearchCollector>(ss, segment_ids);
     handler->Iterate();
     std::sort(segment_ids.begin(), segment_ids.end());
 
+    // get segment information and construct segment json nodes
     std::unordered_map<snapshot::ID_TYPE, std::vector<milvus::json>> json_partition_segments;
     for (auto id : segment_ids) {
         auto segment_commit = ss->GetSegmentCommitBySegmentId(id);
@@ -214,7 +218,15 @@ GetSnapshotInfo(const std::string& collection_name, milvus::json& json_info) {
                     json_file[JSON_PATH] =
                         engine::snapshot::GetResPath<engine::snapshot::SegmentFile>("", pair.second->GetFile());
                     json_file[JSON_FIELD] = field->GetName();
-                    json_file[JSON_FIELD_ELEMENT] = element->GetName();
+
+                    // if the element is index, print index name/type
+                    // else print element name
+                    if (element->GetFtype() == engine::FieldElementType::FET_INDEX) {
+                        json_file[JSON_INDEX_NAME] = element->GetName();
+                        json_file[JSON_INDEX_TYPE] = element->GetTypeName();
+                    } else {
+                        json_file[JSON_FIELD_ELEMENT] = element->GetName();
+                    }
                 }
                 json_files.push_back(json_file);
             }
@@ -228,6 +240,7 @@ GetSnapshotInfo(const std::string& collection_name, milvus::json& json_info) {
         json_partition_segments[segment_commit->GetPartitionId()].push_back(json_segment);
     }
 
+    // construct partition json nodes
     milvus::json json_partitions;
     for (auto pair : partitions) {
         milvus::json json_segments;
diff --git a/core/src/db/Utils.cpp b/core/src/db/Utils.cpp
index c48a92b5d9fc50836fc67ac0ccf9e6c812b1ab1f..407497027e91c511ee251d120fe43be2af7e962a 100644
--- a/core/src/db/Utils.cpp
+++ b/core/src/db/Utils.cpp
@@ -128,6 +128,24 @@ SendExitSignal() {
     kill(pid, SIGUSR2);
 }
 
+void
+GetIDFromChunk(const engine::DataChunkPtr& chunk, engine::IDNumbers& ids) {
+    ids.clear();
+    if (chunk == nullptr) {
+        return;
+    }
+
+    auto pair = chunk->fixed_fields_.find(engine::DEFAULT_UID_NAME);
+    if (pair == chunk->fixed_fields_.end() || pair->second == nullptr) {
+        return;
+    }
+
+    if (!pair->second->data_.empty()) {
+        ids.resize(pair->second->data_.size() / sizeof(engine::IDNumber));
+        memcpy((void*)(ids.data()), pair->second->data_.data(), pair->second->data_.size());
+    }
+}
+
 }  // namespace utils
 }  // namespace engine
 }  // namespace milvus
diff --git a/core/src/db/Utils.h b/core/src/db/Utils.h
index 176ad94f14be4324b30532ab13a6c613f4464543..03b6d075b6f6ac5a6ce75cce50a26b3b0dfdf8ed 100644
--- a/core/src/db/Utils.h
+++ b/core/src/db/Utils.h
@@ -20,11 +20,6 @@
 
 namespace milvus {
 namespace engine {
-namespace snapshot {
-class Segment;
-class Partition;
-class Collection;
-}  // namespace snapshot
 namespace utils {
 
 int64_t
@@ -58,6 +53,9 @@ ParseMetaUri(const std::string& uri, MetaUriInfo& info);
 void
 SendExitSignal();
 
+void
+GetIDFromChunk(const engine::DataChunkPtr& chunk, engine::IDNumbers& ids);
+
 }  // namespace utils
 }  // namespace engine
 }  // namespace milvus
diff --git a/core/src/db/insert/MemCollection.cpp b/core/src/db/insert/MemCollection.cpp
index 7cc966bc4196cd5ea15ce1a1d2d811eec663ad14..24d0b7aec03514171b29c8d32fa7313a8afd8199 100644
--- a/core/src/db/insert/MemCollection.cpp
+++ b/core/src/db/insert/MemCollection.cpp
@@ -238,7 +238,7 @@ MemCollection::ApplyDeletes() {
             }
         }
 
-        segments_op->CommitRowCountDelta(segment->GetID(), delete_docs->GetSize() - pre_del_ids.size(), true);
+        segments_op->CommitRowCountDelta(segment->GetID(), delete_docs->GetCount() - pre_del_ids.size(), true);
 
         segment_writer->WriteDeletedDocs(del_docs_path, delete_docs);
         segment_writer->WriteBloomFilter(bloom_filter_file_path, bloom_filter);
diff --git a/core/src/segment/DeletedDocs.cpp b/core/src/segment/DeletedDocs.cpp
index 26ca61c0c320b963e6167fbb7c445b488f5863a6..67a01b36575f6000728824546afa9fff82804ab0 100644
--- a/core/src/segment/DeletedDocs.cpp
+++ b/core/src/segment/DeletedDocs.cpp
@@ -39,9 +39,14 @@ DeletedDocs::GetDeletedDocs() const {
 //}
 
 size_t
-DeletedDocs::GetSize() const {
+DeletedDocs::GetCount() const {
     return deleted_doc_offsets_.size();
 }
 
+int64_t
+DeletedDocs::Size() {
+    return deleted_doc_offsets_.size() * sizeof(offset_t);
+}
+
 }  // namespace segment
 }  // namespace milvus
diff --git a/core/src/segment/DeletedDocs.h b/core/src/segment/DeletedDocs.h
index 288d4e958760c0b56a77eada5edb720100005f63..eb066a030d3e5bae5358547b78aa8aecbf0c338e 100644
--- a/core/src/segment/DeletedDocs.h
+++ b/core/src/segment/DeletedDocs.h
@@ -20,12 +20,14 @@
 #include <memory>
 #include <vector>
 
+#include "cache/DataObj.h"
+
 namespace milvus {
 namespace segment {
 
 using offset_t = int32_t;
 
-class DeletedDocs {
+class DeletedDocs : public cache::DataObj {
  public:
     explicit DeletedDocs(const std::vector<offset_t>& deleted_doc_offsets);
 
@@ -42,7 +44,10 @@ class DeletedDocs {
     //    GetName() const;
 
     size_t
-    GetSize() const;
+    GetCount() const;
+
+    int64_t
+    Size() override;
 
     //    void
     //    GetBitset(faiss::ConcurrentBitsetPtr& bitset);
diff --git a/core/src/segment/IdBloomFilter.cpp b/core/src/segment/IdBloomFilter.cpp
index 890faa00549b2fb6383c6b2938b09e861f6d8c5c..ed0f77b2556c446764d2d43b82ec4c0def79dcaa 100644
--- a/core/src/segment/IdBloomFilter.cpp
+++ b/core/src/segment/IdBloomFilter.cpp
@@ -76,9 +76,9 @@ IdBloomFilter::Remove(doc_id_t uid) {
 //    return name_;
 //}
 
-size_t
+int64_t
 IdBloomFilter::Size() {
-    return bloom_filter_->num_bytes;
+    return bloom_filter_ ? bloom_filter_->num_bytes : 0;
 }
 
 }  // namespace segment
diff --git a/core/src/segment/IdBloomFilter.h b/core/src/segment/IdBloomFilter.h
index 6c3c891a4f8485c958fcc8cfdef8a738bcd35203..35ad3b657343d663134daadcc37c7736e3d78b4a 100644
--- a/core/src/segment/IdBloomFilter.h
+++ b/core/src/segment/IdBloomFilter.h
@@ -20,6 +20,7 @@
 #include <memory>
 #include <mutex>
 
+#include "cache/DataObj.h"
 #include "dablooms/dablooms.h"
 #include "utils/Status.h"
 
@@ -28,7 +29,7 @@ namespace segment {
 
 using doc_id_t = int64_t;
 
-class IdBloomFilter {
+class IdBloomFilter : public cache::DataObj {
  public:
     explicit IdBloomFilter(scaling_bloom_t* bloom_filter);
 
@@ -46,8 +47,8 @@ class IdBloomFilter {
     Status
     Remove(doc_id_t uid);
 
-    size_t
-    Size();
+    int64_t
+    Size() override;
 
     //    const std::string&
     //    GetName() const;
diff --git a/core/src/segment/SegmentReader.cpp b/core/src/segment/SegmentReader.cpp
index 2ec47f22fecf6ec42bcff53554f4aa596ce95133..a5409044c160753b231b3f0fe128ada40a0d0cb1 100644
--- a/core/src/segment/SegmentReader.cpp
+++ b/core/src/segment/SegmentReader.cpp
@@ -21,6 +21,7 @@
 #include <memory>
 #include <utility>
 
+#include "cache/CpuCacheMgr.h"
 #include "codecs/Codec.h"
 #include "db/SnapshotUtils.h"
 #include "db/Types.h"
@@ -115,8 +116,16 @@ SegmentReader::LoadField(const std::string& field_name, engine::BinaryDataPtr& r
         std::string file_path =
             engine::snapshot::GetResPath<engine::snapshot::SegmentFile>(dir_collections_, raw_visitor->GetFile());
 
-        auto& ss_codec = codec::Codec::instance();
-        ss_codec.GetBlockFormat()->Read(fs_ptr_, file_path, raw);
+        // if the data is in cache, no need to read file
+        auto data_obj = cache::CpuCacheMgr::GetInstance().GetItem(file_path);
+        if (data_obj == nullptr) {
+            auto& ss_codec = codec::Codec::instance();
+            ss_codec.GetBlockFormat()->Read(fs_ptr_, file_path, raw);
+
+            cache::CpuCacheMgr::GetInstance().InsertItem(file_path, raw);  // put into cache
+        } else {
+            raw = std::static_pointer_cast<engine::BinaryData>(data_obj);
+        }
 
         field_map.insert(std::make_pair(field_name, raw));
     } catch (std::exception& e) {
@@ -265,62 +274,80 @@ SegmentReader::LoadVectorIndex(const std::string& field_name, knowhere::VecIndex
         knowhere::BinarySet index_data;
         knowhere::BinaryPtr raw_data, compress_data;
 
-        auto read_raw = [&]() -> void {
-            engine::BinaryDataPtr fixed_data;
-            auto status = segment_ptr_->GetFixedFieldData(field_name, fixed_data);
-            if (status.ok()) {
-                ss_codec.GetVectorIndexFormat()->ConvertRaw(fixed_data, raw_data);
-            } else if (auto visitor = field_visitor->GetElementVisitor(engine::FieldElementType::FET_RAW)) {
-                auto file_path =
-                    engine::snapshot::GetResPath<engine::snapshot::SegmentFile>(dir_collections_, visitor->GetFile());
-                ss_codec.GetVectorIndexFormat()->ReadRaw(fs_ptr_, file_path, raw_data);
-            }
-        };
-
-        // if index not specified, or index file not created, return IDMAP
+        // if index not specified, or index file not created, return a temp index(IDMAP type)
         auto index_visitor = field_visitor->GetElementVisitor(engine::FieldElementType::FET_INDEX);
         if (index_visitor == nullptr || index_visitor->GetFile() == nullptr) {
-            auto& json = field->GetParams();
-            if (json.find(knowhere::meta::DIM) == json.end()) {
-                return Status(DB_ERROR, "Vector field dimension undefined");
+            auto temp_index_path = engine::snapshot::GetResPath<engine::snapshot::Segment>(dir_collections_, segment);
+            temp_index_path += "/";
+            std::string temp_index_name = field_name + ".idmap";
+            temp_index_path += temp_index_name;
+
+            // if the data is in cache, no need to read file
+            auto data_obj = cache::CpuCacheMgr::GetInstance().GetItem(temp_index_path);
+            if (data_obj != nullptr) {
+                index_ptr = std::static_pointer_cast<knowhere::VecIndex>(data_obj);
+                segment_ptr_->SetVectorIndex(field_name, index_ptr);
+            } else {
+                auto& json = field->GetParams();
+                if (json.find(knowhere::meta::DIM) == json.end()) {
+                    return Status(DB_ERROR, "Vector field dimension undefined");
+                }
+                int64_t dimension = json[knowhere::meta::DIM];
+                engine::BinaryDataPtr raw;
+                STATUS_CHECK(LoadField(field_name, raw));
+
+                auto dataset = knowhere::GenDataset(segment_commit->GetRowCount(), dimension, raw->data_.data());
+
+                // construct IDMAP index
+                knowhere::VecIndexFactory& vec_index_factory = knowhere::VecIndexFactory::GetInstance();
+                index_ptr = vec_index_factory.CreateVecIndex(knowhere::IndexEnum::INDEX_FAISS_IDMAP,
+                                                             knowhere::IndexMode::MODE_CPU);
+                milvus::json conf{{knowhere::meta::DIM, dimension}};
+                conf[engine::PARAM_INDEX_METRIC_TYPE] = knowhere::Metric::L2;
+                index_ptr->Train(knowhere::DatasetPtr(), conf);
+                index_ptr->AddWithoutIds(dataset, conf);
+                index_ptr->SetUids(uids);
+                index_ptr->SetBlacklist(concurrent_bitset_ptr);
+                segment_ptr_->SetVectorIndex(field_name, index_ptr);
             }
-            int64_t dimension = json[knowhere::meta::DIM];
-            engine::BinaryDataPtr raw;
-            STATUS_CHECK(LoadField(field_name, raw));
-
-            auto dataset = knowhere::GenDataset(segment_commit->GetRowCount(), dimension, raw->data_.data());
-
-            knowhere::VecIndexFactory& vec_index_factory = knowhere::VecIndexFactory::GetInstance();
-            index_ptr =
-                vec_index_factory.CreateVecIndex(knowhere::IndexEnum::INDEX_FAISS_IDMAP, knowhere::IndexMode::MODE_CPU);
-            milvus::json conf{{knowhere::meta::DIM, dimension}};
-            conf[engine::PARAM_INDEX_METRIC_TYPE] = knowhere::Metric::L2;
-            index_ptr->Train(knowhere::DatasetPtr(), conf);
-            index_ptr->AddWithoutIds(dataset, conf);
-            index_ptr->SetUids(uids);
-            index_ptr->SetBlacklist(concurrent_bitset_ptr);
-            segment_ptr_->SetVectorIndex(field_name, index_ptr);
+
             return Status::OK();
         }
 
         // read index file
-        std::string file_path =
+        std::string index_file_path =
             engine::snapshot::GetResPath<engine::snapshot::SegmentFile>(dir_collections_, index_visitor->GetFile());
-        ss_codec.GetVectorIndexFormat()->ReadIndex(fs_ptr_, file_path, index_data);
+        // if the data is in cache, no need to read file
+        auto data_obj = cache::CpuCacheMgr::GetInstance().GetItem(index_file_path);
+        if (data_obj != nullptr) {
+            index_ptr = std::static_pointer_cast<knowhere::VecIndex>(data_obj);
+            segment_ptr_->SetVectorIndex(field_name, index_ptr);
 
-        auto index_type = index_visitor->GetElement()->GetTypeName();
+            return Status::OK();
+        }
+
+        ss_codec.GetVectorIndexFormat()->ReadIndex(fs_ptr_, index_file_path, index_data);
 
         // for some kinds index(IVF), read raw file
+        auto index_type = index_visitor->GetElement()->GetTypeName();
         if (index_type == knowhere::IndexEnum::INDEX_FAISS_IVFFLAT || index_type == knowhere::IndexEnum::INDEX_NSG ||
             index_type == knowhere::IndexEnum::INDEX_HNSW) {
-            read_raw();
+            engine::BinaryDataPtr fixed_data;
+            auto status = segment_ptr_->GetFixedFieldData(field_name, fixed_data);
+            if (status.ok()) {
+                ss_codec.GetVectorIndexFormat()->ConvertRaw(fixed_data, raw_data);
+            } else if (auto visitor = field_visitor->GetElementVisitor(engine::FieldElementType::FET_RAW)) {
+                auto file_path =
+                    engine::snapshot::GetResPath<engine::snapshot::SegmentFile>(dir_collections_, visitor->GetFile());
+                ss_codec.GetVectorIndexFormat()->ReadRaw(fs_ptr_, file_path, raw_data);
+            }
         }
 
         // for some kinds index(SQ8), read compress file
         if (index_type == knowhere::IndexEnum::INDEX_FAISS_IVFSQ8NR ||
             index_type == knowhere::IndexEnum::INDEX_HNSW_SQ8NM) {
             if (auto visitor = field_visitor->GetElementVisitor(engine::FieldElementType::FET_COMPRESS_SQ8)) {
-                file_path =
+                auto file_path =
                     engine::snapshot::GetResPath<engine::snapshot::SegmentFile>(dir_collections_, visitor->GetFile());
                 ss_codec.GetVectorIndexFormat()->ReadCompress(fs_ptr_, file_path, compress_data);
             }
@@ -331,6 +358,8 @@ SegmentReader::LoadVectorIndex(const std::string& field_name, knowhere::VecIndex
         index_ptr->SetUids(uids);
         index_ptr->SetBlacklist(concurrent_bitset_ptr);
         segment_ptr_->SetVectorIndex(field_name, index_ptr);
+
+        cache::CpuCacheMgr::GetInstance().InsertItem(index_file_path, index_ptr);  // put into cache
     } catch (std::exception& e) {
         std::string err_msg = "Failed to load vector index: " + std::string(e.what());
         LOG_ENGINE_ERROR_ << err_msg;
@@ -361,7 +390,15 @@ SegmentReader::LoadStructuredIndex(const std::string& field_name, knowhere::Inde
         if (index_visitor && index_visitor->GetFile() != nullptr) {
             std::string file_path =
                 engine::snapshot::GetResPath<engine::snapshot::SegmentFile>(dir_collections_, index_visitor->GetFile());
-            ss_codec.GetStructuredIndexFormat()->Read(fs_ptr_, file_path, index_ptr);
+
+            // if the data is in cache, no need to read file
+            auto data_obj = cache::CpuCacheMgr::GetInstance().GetItem(file_path);
+            if (data_obj == nullptr) {
+                ss_codec.GetStructuredIndexFormat()->Read(fs_ptr_, file_path, index_ptr);
+                cache::CpuCacheMgr::GetInstance().InsertItem(file_path, index_ptr);  // put into cache
+            } else {
+                index_ptr = std::static_pointer_cast<knowhere::Index>(data_obj);
+            }
 
             segment_ptr_->SetStructuredIndex(field_name, index_ptr);
         }
@@ -412,12 +449,22 @@ SegmentReader::LoadBloomFilter(segment::IdBloomFilterPtr& id_bloom_filter_ptr) {
         auto visitor = uid_field_visitor->GetElementVisitor(engine::FieldElementType::FET_BLOOM_FILTER);
         std::string file_path =
             engine::snapshot::GetResPath<engine::snapshot::SegmentFile>(dir_collections_, visitor->GetFile());
+        if (!boost::filesystem::exists(file_path + codec::IdBloomFilterFormat::FilePostfix())) {
+            return Status::OK();  // file doesn't exist
+        }
 
-        auto& ss_codec = codec::Codec::instance();
-        ss_codec.GetIdBloomFilterFormat()->Read(fs_ptr_, file_path, id_bloom_filter_ptr);
+        // if the data is in cache, no need to read file
+        auto data_obj = cache::CpuCacheMgr::GetInstance().GetItem(file_path);
+        if (data_obj == nullptr) {
+            auto& ss_codec = codec::Codec::instance();
+            ss_codec.GetIdBloomFilterFormat()->Read(fs_ptr_, file_path, id_bloom_filter_ptr);
+        } else {
+            id_bloom_filter_ptr = std::static_pointer_cast<segment::IdBloomFilter>(data_obj);
+        }
 
         if (id_bloom_filter_ptr) {
             segment_ptr_->SetBloomFilter(id_bloom_filter_ptr);
+            cache::CpuCacheMgr::GetInstance().InsertItem(file_path, id_bloom_filter_ptr);  // put into cache
         }
     } catch (std::exception& e) {
         std::string err_msg = "Failed to load bloom filter: " + std::string(e.what());
@@ -439,15 +486,22 @@ SegmentReader::LoadDeletedDocs(segment::DeletedDocsPtr& deleted_docs_ptr) {
         auto visitor = uid_field_visitor->GetElementVisitor(engine::FieldElementType::FET_DELETED_DOCS);
         std::string file_path =
             engine::snapshot::GetResPath<engine::snapshot::SegmentFile>(dir_collections_, visitor->GetFile());
-        if (!boost::filesystem::exists(file_path)) {
+        if (!boost::filesystem::exists(file_path + codec::DeletedDocsFormat::FilePostfix())) {
             return Status::OK();  // file doesn't exist
         }
 
-        auto& ss_codec = codec::Codec::instance();
-        ss_codec.GetDeletedDocsFormat()->Read(fs_ptr_, file_path, deleted_docs_ptr);
+        // if the data is in cache, no need to read file
+        auto data_obj = cache::CpuCacheMgr::GetInstance().GetItem(file_path);
+        if (data_obj == nullptr) {
+            auto& ss_codec = codec::Codec::instance();
+            ss_codec.GetDeletedDocsFormat()->Read(fs_ptr_, file_path, deleted_docs_ptr);
+        } else {
+            deleted_docs_ptr = std::static_pointer_cast<segment::DeletedDocs>(data_obj);
+        }
 
         if (deleted_docs_ptr) {
             segment_ptr_->SetDeletedDocs(deleted_docs_ptr);
+            cache::CpuCacheMgr::GetInstance().InsertItem(file_path, deleted_docs_ptr);  // put into cache
         }
     } catch (std::exception& e) {
         std::string err_msg = "Failed to load deleted docs: " + std::string(e.what());
@@ -463,7 +517,7 @@ SegmentReader::ReadDeletedDocsSize(size_t& size) {
         size = 0;
         auto deleted_docs_ptr = segment_ptr_->GetDeletedDocs();
         if (deleted_docs_ptr != nullptr) {
-            size = deleted_docs_ptr->GetSize();
+            size = deleted_docs_ptr->GetCount();
             return Status::OK();  // already exist
         }
 
@@ -471,7 +525,7 @@ SegmentReader::ReadDeletedDocsSize(size_t& size) {
         auto visitor = uid_field_visitor->GetElementVisitor(engine::FieldElementType::FET_DELETED_DOCS);
         std::string file_path =
             engine::snapshot::GetResPath<engine::snapshot::SegmentFile>(dir_collections_, visitor->GetFile());
-        if (!boost::filesystem::exists(file_path)) {
+        if (!boost::filesystem::exists(file_path + codec::DeletedDocsFormat::FilePostfix())) {
             return Status::OK();  // file doesn't exist
         }
 
diff --git a/core/unittest/db/test_db.cpp b/core/unittest/db/test_db.cpp
index 4a8a8764ab820a076b1f0a197ae72b1b688e5cb6..a9d582e5dd17452c0ed4d79678a250e7721af14c 100644
--- a/core/unittest/db/test_db.cpp
+++ b/core/unittest/db/test_db.cpp
@@ -223,9 +223,9 @@ BuildEntities2(uint64_t n, uint64_t batch_index, milvus::engine::DataChunkPtr& d
     }
 
     milvus::engine::BinaryDataPtr raw = std::make_shared<milvus::engine::BinaryData>();
+    data_chunk->fixed_fields_["float_vector"] = raw;
     raw->data_.resize(vectors.float_data_.size() * sizeof(float));
     memcpy(raw->data_.data(), vectors.float_data_.data(), vectors.float_data_.size() * sizeof(float));
-    data_chunk->fixed_fields_["float_vector"] = raw;
 
     std::vector<int64_t> value_1;
     value_1.resize(n);
@@ -236,9 +236,9 @@ BuildEntities2(uint64_t n, uint64_t batch_index, milvus::engine::DataChunkPtr& d
 
     {
         milvus::engine::BinaryDataPtr raw = std::make_shared<milvus::engine::BinaryData>();
+        data_chunk->fixed_fields_["int64"] = raw;
         raw->data_.resize(value_1.size() * sizeof(int64_t));
         memcpy(raw->data_.data(), value_1.data(), value_1.size() * sizeof(int64_t));
-        data_chunk->fixed_fields_["int64"] = raw;
     }
 }
 }  // namespace
@@ -508,6 +508,8 @@ TEST_F(DBTest, MergeTest) {
         status = db_->Insert(collection_name, "", data_chunk);
         ASSERT_TRUE(status.ok());
 
+        data_chunk->fixed_fields_.erase(milvus::engine::DEFAULT_UID_NAME); // clear auto-generated id
+
         status = db_->Flush();
         ASSERT_TRUE(status.ok());
     }
@@ -568,6 +570,42 @@ TEST_F(DBTest, MergeTest) {
     ASSERT_EQ(expect_file_paths.size(), segment_file_paths.size());
 }
 
+TEST_F(DBTest, CompactTest) {
+    std::string collection_name = "COMPACT_TEST";
+    auto status = CreateCollection2(db_, collection_name, 0);
+    ASSERT_TRUE(status.ok());
+
+    const uint64_t entity_count = 10000;
+    milvus::engine::DataChunkPtr data_chunk;
+    BuildEntities(entity_count, 0, data_chunk);
+
+    status = db_->Insert(collection_name, "", data_chunk);
+    ASSERT_TRUE(status.ok());
+
+    status = db_->Flush();
+    ASSERT_TRUE(status.ok());
+
+    milvus::engine::IDNumbers entity_ids;
+    milvus::engine::utils::GetIDFromChunk(data_chunk, entity_ids);
+    ASSERT_EQ(entity_ids.size(), entity_count);
+
+//    int64_t delete_count = 10;
+//    entity_ids.resize(delete_count);
+//    status = db_->DeleteEntityByID(collection_name, entity_ids);
+//    ASSERT_TRUE(status.ok());
+//
+//    status = db_->Flush();
+//    ASSERT_TRUE(status.ok());
+//
+//    status = db_->Compact(dummy_context_, collection_name);
+//    ASSERT_TRUE(status.ok());
+//
+//    int64_t row_count = 0;
+//    status = db_->CountEntities(collection_name, row_count);
+//    ASSERT_TRUE(status.ok());
+//    ASSERT_EQ(row_count, entity_count - delete_count);
+}
+
 TEST_F(DBTest, IndexTest) {
     std::string collection_name = "INDEX_TEST";
     auto status = CreateCollection2(db_, collection_name, 0);
@@ -656,6 +694,8 @@ TEST_F(DBTest, StatsTest) {
     status = db_->Insert(collection_name, "", data_chunk);
     ASSERT_TRUE(status.ok());
 
+    data_chunk->fixed_fields_.erase(milvus::engine::DEFAULT_UID_NAME); // clear auto-generated id
+
     status = db_->Insert(collection_name, partition_name, data_chunk);
     ASSERT_TRUE(status.ok());