diff --git a/cpp/src/db/DBImpl.cpp b/cpp/src/db/DBImpl.cpp
index 599db01ef9..e2246c95cd 100644
--- a/cpp/src/db/DBImpl.cpp
+++ b/cpp/src/db/DBImpl.cpp
@@ -22,7 +22,7 @@ DBImpl::DBImpl(const Options& options)
       _shutting_down(false),
       bg_build_index_started_(false),
       _pMeta(new meta::DBMetaImpl(_options.meta)),
-      _pMemMgr(new MemManager(_pMeta)) {
+      _pMemMgr(new MemManager(_pMeta, _options)) {
     start_timer_task(_options.memory_sync_interval);
 }
 
@@ -147,7 +147,7 @@ Status DBImpl::background_merge_files(const std::string& group_id) {
 
     for (auto& kv : raw_files) {
         auto files = kv.second;
-        if (files.size() <= _options.raw_file_merge_trigger_number) {
+        if (files.size() <= _options.merge_trigger_number) {
             continue;
         }
         has_merge = true;
diff --git a/cpp/src/db/MemManager.cpp b/cpp/src/db/MemManager.cpp
index 5b791223a6..4c844a7fab 100644
--- a/cpp/src/db/MemManager.cpp
+++ b/cpp/src/db/MemManager.cpp
@@ -13,13 +13,13 @@ namespace zilliz {
 namespace vecwise {
 namespace engine {
 
-MemVectors::MemVectors(const std::string& group_id,
-        size_t dimension, const std::string& file_location) :
-    group_id_(group_id),
-    _file_location(file_location),
+MemVectors::MemVectors(const std::shared_ptr<meta::Meta>& meta_ptr,
+        const meta::GroupFileSchema& schema, const Options& options)
+  : pMeta_(meta_ptr),
+    options_(options),
+    schema_(schema),
     _pIdGenerator(new SimpleIDGenerator()),
-    _dimension(dimension),
-    pIndex_(faiss::index_factory(_dimension, "IDMap,Flat")) {
+    pIndex_(faiss::index_factory(schema_.dimension, "IDMap,Flat")) {
 }
 
 void MemVectors::add(size_t n_, const float* vectors_, IDNumbers& vector_ids_) {
@@ -35,7 +35,7 @@ size_t MemVectors::total() const {
 }
 
 size_t MemVectors::approximate_size() const {
-    return total() * _dimension;
+    return total() * schema_.dimension;
 }
 
 Status MemVectors::serialize(std::string& group_id) {
@@ -45,8 +45,13 @@ Status MemVectors::serialize(std::string& group_id) {
     /* std::cout << pIndex_->ntotal << std::endl; */
     /* std::cout << _file_location << std::endl; */
     /* faiss::write_index(pIndex_, _file_location.c_str()); */
-    write_index(pIndex_, _file_location.c_str());
-    group_id = group_id_;
+    group_id = schema_.group_id;
+    auto rows = approximate_size();
+    write_index(pIndex_, schema_.location.c_str());
+    schema_.rows = rows;
+    schema_.file_type = (rows >= options_.index_trigger_size) ?
+        meta::GroupFileSchema::TO_INDEX : meta::GroupFileSchema::RAW;
+    pMeta_->update_group_file(schema_);
     return Status::OK();
 }
 
@@ -78,9 +83,7 @@ VectorsPtr MemManager::get_mem_by_group(const std::string& group_id) {
         return nullptr;
     }
 
-    _memMap[group_id] = std::shared_ptr<MemVectors>(new MemVectors(group_file.group_id,
-                group_file.dimension,
-                group_file.location));
+    _memMap[group_id] = std::shared_ptr<MemVectors>(new MemVectors(_pMeta, group_file, options_));
     return _memMap[group_id];
 }
 
diff --git a/cpp/src/db/MemManager.h b/cpp/src/db/MemManager.h
index 48aacc4fb6..a87c54c14e 100644
--- a/cpp/src/db/MemManager.h
+++ b/cpp/src/db/MemManager.h
@@ -8,6 +8,7 @@
 #include <mutex>
 #include "IDGenerator.h"
 #include "Status.h"
+#include "Meta.h"
 
 namespace faiss {
     class Index;
@@ -24,9 +25,8 @@ namespace meta {
 
 class MemVectors {
 public:
-    explicit MemVectors(const std::string& group_id,
-            size_t dimension,
-            const std::string& file_location);
+    explicit MemVectors(const std::shared_ptr<meta::Meta>&,
+            const meta::GroupFileSchema&, const Options&);
 
     void add(size_t n_, const float* vectors_, IDNumbers& vector_ids_);
 
@@ -38,17 +38,17 @@ public:
 
     ~MemVectors();
 
-    const std::string& location() const { return _file_location; }
+    const std::string& location() const { return schema_.location; }
 
 private:
     MemVectors() = delete;
     MemVectors(const MemVectors&) = delete;
     MemVectors& operator=(const MemVectors&) = delete;
 
-    std::string group_id_;
-    const std::string _file_location;
+    std::shared_ptr<meta::Meta> pMeta_;
+    Options options_;
+    meta::GroupFileSchema schema_;
     IDGenerator* _pIdGenerator;
-    size_t _dimension;
     faiss::Index* pIndex_;
 
 }; // MemVectors
@@ -58,8 +58,8 @@ typedef std::shared_ptr<MemVectors> VectorsPtr;
 
 class MemManager {
 public:
-    MemManager(const std::shared_ptr<meta::Meta>& meta_)
-        : _pMeta(meta_) /*_last_compact_time(std::time(nullptr))*/ {}
+    MemManager(const std::shared_ptr<meta::Meta>& meta_, const Options& options)
+        : _pMeta(meta_), options_(options) {}
 
     VectorsPtr get_mem_by_group(const std::string& group_id_);
 
@@ -78,7 +78,7 @@ private:
     MemMap _memMap;
     ImmMemPool _immMems;
     std::shared_ptr<meta::Meta> _pMeta;
-    /* std::time_t _last_compact_time; */
+    Options options_;
     std::mutex _mutex;
 }; // MemManager
 
diff --git a/cpp/src/db/Options.h b/cpp/src/db/Options.h
index 12d57ee28d..8e9dad2b47 100644
--- a/cpp/src/db/Options.h
+++ b/cpp/src/db/Options.h
@@ -19,8 +19,8 @@ struct DBMetaOptions {
 struct Options {
     Options();
     uint16_t  memory_sync_interval = 10;
-    uint16_t  raw_file_merge_trigger_number = 100;
-    size_t  raw_to_index_trigger_size = 100000;
+    uint16_t  merge_trigger_number = 100;
+    size_t  index_trigger_size = 100000;
     Env* env;
     DBMetaOptions meta;
 }; // Options