diff --git a/cpp/src/db/DB.cpp b/cpp/src/db/DB.cpp
index 610e353358078496c685d1be27843fcf9d3b622e..bfb83a446c061ebc3dd6dbb97f2249a953a4f071 100644
--- a/cpp/src/db/DB.cpp
+++ b/cpp/src/db/DB.cpp
@@ -16,15 +16,7 @@ namespace engine {
 DB::~DB() {}
 
 void DB::Open(const Options& options, DB** dbptr) {
-    *dbptr = nullptr;
-
-#ifdef GPU_VERSION
-    std::string default_index_type{"Faiss,IVF"};
-#else
-    std::string default_index_type{"Faiss,IDMap"};
-#endif
-
-    *dbptr = DBFactory::Build(options, default_index_type);
+    *dbptr = DBFactory::Build(options);
     return;
 }
 
diff --git a/cpp/src/db/DBImpl.inl b/cpp/src/db/DBImpl.cpp
similarity index 75%
rename from cpp/src/db/DBImpl.inl
rename to cpp/src/db/DBImpl.cpp
index 10f16ee9eb77dd6a441c27ee810b2df0807c6792..ea380adff8419b7ce28e24f90a9022d008dedfe0 100644
--- a/cpp/src/db/DBImpl.inl
+++ b/cpp/src/db/DBImpl.cpp
@@ -3,11 +3,10 @@
  * Unauthorized copying of this file, via any medium is strictly prohibited.
  * Proprietary and confidential.
  ******************************************************************************/
-#pragma once
-
 #include "DBImpl.h"
 #include "DBMetaImpl.h"
 #include "Env.h"
+#include "EngineFactory.h"
 #include "metrics/Metrics.h"
 #include "scheduler/SearchScheduler.h"
 
@@ -23,80 +22,107 @@ namespace zilliz {
 namespace vecwise {
 namespace engine {
 
+namespace {
+
+void CollectInsertMetrics(double total_time, size_t n, bool succeed) {
+    double avg_time = total_time / n;
+    for (int i = 0; i < n; ++i) {
+        server::Metrics::GetInstance().AddVectorsDurationHistogramOberve(avg_time);
+    }
+
+//    server::Metrics::GetInstance().add_vector_duration_seconds_quantiles().Observe((average_time));
+    if (succeed) {
+        server::Metrics::GetInstance().AddVectorsSuccessTotalIncrement(n);
+        server::Metrics::GetInstance().AddVectorsSuccessGaugeSet(n);
+    }
+    else {
+        server::Metrics::GetInstance().AddVectorsFailTotalIncrement(n);
+        server::Metrics::GetInstance().AddVectorsFailGaugeSet(n);
+    }
+}
+
+void CollectQueryMetrics(double total_time, size_t nq) {
+    for (int i = 0; i < nq; ++i) {
+        server::Metrics::GetInstance().QueryResponseSummaryObserve(total_time);
+    }
+    auto average_time = total_time / nq;
+    server::Metrics::GetInstance().QueryVectorResponseSummaryObserve(average_time, nq);
+    server::Metrics::GetInstance().QueryVectorResponsePerSecondGaugeSet(double (nq) / total_time);
+}
+
+void CollectFileMetrics(meta::TableFileSchema::FILE_TYPE file_type, size_t file_size, double total_time) {
+    switch(file_type) {
+        case meta::TableFileSchema::RAW:
+        case meta::TableFileSchema::TO_INDEX: {
+            server::Metrics::GetInstance().SearchRawDataDurationSecondsHistogramObserve(total_time);
+            server::Metrics::GetInstance().RawFileSizeHistogramObserve(file_size);
+            server::Metrics::GetInstance().RawFileSizeTotalIncrement(file_size);
+            server::Metrics::GetInstance().RawFileSizeGaugeSet(file_size);
+            break;
+        }
+        default: {
+            server::Metrics::GetInstance().SearchIndexDataDurationSecondsHistogramObserve(total_time);
+            server::Metrics::GetInstance().IndexFileSizeHistogramObserve(file_size);
+            server::Metrics::GetInstance().IndexFileSizeTotalIncrement(file_size);
+            server::Metrics::GetInstance().IndexFileSizeGaugeSet(file_size);
+            break;
+        }
+    }
+}
+
+}
 
-template<typename EngineT>
-DBImpl<EngineT>::DBImpl(const Options& options)
+
+DBImpl::DBImpl(const Options& options)
     : env_(options.env),
       options_(options),
       bg_compaction_scheduled_(false),
       shutting_down_(false),
       bg_build_index_started_(false),
       pMeta_(new meta::DBMetaImpl(options_.meta)),
-      pMemMgr_(new MemManager<EngineT>(pMeta_, options_)) {
+      pMemMgr_(new MemManager(pMeta_, options_)) {
     StartTimerTasks(options_.memory_sync_interval);
 }
 
-template<typename EngineT>
-Status DBImpl<EngineT>::CreateTable(meta::TableSchema& table_schema) {
+Status DBImpl::CreateTable(meta::TableSchema& table_schema) {
     return pMeta_->CreateTable(table_schema);
 }
 
-template<typename EngineT>
-Status DBImpl<EngineT>::DescribeTable(meta::TableSchema& table_schema) {
+Status DBImpl::DescribeTable(meta::TableSchema& table_schema) {
     return pMeta_->DescribeTable(table_schema);
 }
 
-template<typename EngineT>
-Status DBImpl<EngineT>::HasTable(const std::string& table_id, bool& has_or_not) {
+Status DBImpl::HasTable(const std::string& table_id, bool& has_or_not) {
     return pMeta_->HasTable(table_id, has_or_not);
 }
 
-template<typename EngineT>
-Status DBImpl<EngineT>::InsertVectors(const std::string& table_id_,
+Status DBImpl::InsertVectors(const std::string& table_id_,
         size_t n, const float* vectors, IDNumbers& vector_ids_) {
 
     auto start_time = METRICS_NOW_TIME;
     Status status = pMemMgr_->InsertVectors(table_id_, n, vectors, vector_ids_);
     auto end_time = METRICS_NOW_TIME;
-
+    double total_time = METRICS_MICROSECONDS(start_time,end_time);
 //    std::chrono::microseconds time_span = std::chrono::duration_cast<std::chrono::microseconds>(end_time - start_time);
 //    double average_time = double(time_span.count()) / n;
 
-    double total_time = METRICS_MICROSECONDS(start_time,end_time);
-    double avg_time = total_time / n;
-    for (int i = 0; i < n; ++i) {
-        server::Metrics::GetInstance().AddVectorsDurationHistogramOberve(avg_time);
-    }
-
-//    server::Metrics::GetInstance().add_vector_duration_seconds_quantiles().Observe((average_time));
-    if (!status.ok()) {
-        server::Metrics::GetInstance().AddVectorsFailTotalIncrement(n);
-        server::Metrics::GetInstance().AddVectorsFailGaugeSet(n);
-        return status;
-    }
-    server::Metrics::GetInstance().AddVectorsSuccessTotalIncrement(n);
-    server::Metrics::GetInstance().AddVectorsSuccessGaugeSet(n);
+    CollectInsertMetrics(total_time, n, status.ok());
+    return status;
 }
 
-template<typename EngineT>
-Status DBImpl<EngineT>::Query(const std::string &table_id, size_t k, size_t nq,
+Status DBImpl::Query(const std::string &table_id, size_t k, size_t nq,
                       const float *vectors, QueryResults &results) {
     auto start_time = METRICS_NOW_TIME;
     meta::DatesT dates = {meta::Meta::GetDate()};
     Status result = Query(table_id, k, nq, vectors, dates, results);
     auto end_time = METRICS_NOW_TIME;
     auto total_time = METRICS_MICROSECONDS(start_time,end_time);
-    auto average_time = total_time / nq;
-    for (int i = 0; i < nq; ++i) {
-        server::Metrics::GetInstance().QueryResponseSummaryObserve(total_time);
-    }
-    server::Metrics::GetInstance().QueryVectorResponseSummaryObserve(average_time, nq);
-    server::Metrics::GetInstance().QueryVectorResponsePerSecondGaugeSet(double (nq) / total_time);
+
+    CollectQueryMetrics(total_time, nq);
     return result;
 }
 
-template<typename EngineT>
-Status DBImpl<EngineT>::Query(const std::string& table_id, size_t k, size_t nq,
+Status DBImpl::Query(const std::string& table_id, size_t k, size_t nq,
         const float* vectors, const meta::DatesT& dates, QueryResults& results) {
 #if 0
     return QuerySync(table_id, k, nq, vectors, dates, results);
@@ -105,8 +131,7 @@ Status DBImpl<EngineT>::Query(const std::string& table_id, size_t k, size_t nq,
 #endif
 }
 
-template<typename EngineT>
-Status DBImpl<EngineT>::QuerySync(const std::string& table_id, size_t k, size_t nq,
+Status DBImpl::QuerySync(const std::string& table_id, size_t k, size_t nq,
                  const float* vectors, const meta::DatesT& dates, QueryResults& results) {
     meta::DatePartionedTableFilesSchema files;
     auto status = pMeta_->FilesToSearch(table_id, dates, files);
@@ -160,38 +185,20 @@ Status DBImpl<EngineT>::QuerySync(const std::string& table_id, size_t k, size_t
         auto search_in_index = [&](meta::TableFilesSchema& file_vec) -> void {
             for (auto &file : file_vec) {
 
-                EngineT index(file.dimension, file.location);
-                index.Load();
-                auto file_size = index.PhysicalSize()/(1024*1024);
+                ExecutionEnginePtr index = EngineFactory::Build(file.dimension, file.location, (EngineType)file.engine_type_);
+                index->Load();
+                auto file_size = index->PhysicalSize();
                 search_set_size += file_size;
 
                 LOG(DEBUG) << "Search file_type " << file.file_type << " Of Size: "
-                    << file_size << " M";
+                    << file_size/(1024*1024) << " M";
 
-                int inner_k = index.Count() < k ? index.Count() : k;
+                int inner_k = index->Count() < k ? index->Count() : k;
                 auto start_time = METRICS_NOW_TIME;
-                index.Search(nq, vectors, inner_k, output_distence, output_ids);
+                index->Search(nq, vectors, inner_k, output_distence, output_ids);
                 auto end_time = METRICS_NOW_TIME;
                 auto total_time = METRICS_MICROSECONDS(start_time, end_time);
-                if(file.file_type == meta::TableFileSchema::RAW) {
-                    server::Metrics::GetInstance().SearchRawDataDurationSecondsHistogramObserve(total_time);
-                    server::Metrics::GetInstance().RawFileSizeHistogramObserve(file_size*1024*1024);
-                    server::Metrics::GetInstance().RawFileSizeTotalIncrement(file_size*1024*1024);
-                    server::Metrics::GetInstance().RawFileSizeGaugeSet(file_size*1024*1024);
-
-                } else if(file.file_type == meta::TableFileSchema::TO_INDEX) {
-
-                    server::Metrics::GetInstance().SearchRawDataDurationSecondsHistogramObserve(total_time);
-                    server::Metrics::GetInstance().RawFileSizeHistogramObserve(file_size*1024*1024);
-                    server::Metrics::GetInstance().RawFileSizeTotalIncrement(file_size*1024*1024);
-                    server::Metrics::GetInstance().RawFileSizeGaugeSet(file_size*1024*1024);
-
-                } else {
-                    server::Metrics::GetInstance().SearchIndexDataDurationSecondsHistogramObserve(total_time);
-                    server::Metrics::GetInstance().IndexFileSizeHistogramObserve(file_size*1024*1024);
-                    server::Metrics::GetInstance().IndexFileSizeTotalIncrement(file_size*1024*1024);
-                    server::Metrics::GetInstance().IndexFileSizeGaugeSet(file_size*1024*1024);
-                }
+                CollectFileMetrics((meta::TableFileSchema::FILE_TYPE)file.file_type, file_size, total_time);
                 cluster(output_ids, output_distence, inner_k); // cluster to each query
                 memset(output_distence, 0, k * nq * sizeof(float));
                 memset(output_ids, 0, k * nq * sizeof(long));
@@ -258,8 +265,7 @@ Status DBImpl<EngineT>::QuerySync(const std::string& table_id, size_t k, size_t
     return Status::OK();
 }
 
-template<typename EngineT>
-Status DBImpl<EngineT>::QueryAsync(const std::string& table_id, size_t k, size_t nq,
+Status DBImpl::QueryAsync(const std::string& table_id, size_t k, size_t nq,
                   const float* vectors, const meta::DatesT& dates, QueryResults& results) {
     meta::DatePartionedTableFilesSchema files;
     auto status = pMeta_->FilesToSearch(table_id, dates, files);
@@ -292,13 +298,12 @@ Status DBImpl<EngineT>::QueryAsync(const std::string& table_id, size_t k, size_t
     return Status::OK();
 }
 
-template<typename EngineT>
-void DBImpl<EngineT>::StartTimerTasks(int interval) {
-    bg_timer_thread_ = std::thread(&DBImpl<EngineT>::BackgroundTimerTask, this, interval);
+void DBImpl::StartTimerTasks(int interval) {
+    bg_timer_thread_ = std::thread(&DBImpl::BackgroundTimerTask, this, interval);
 }
 
-template<typename EngineT>
-void DBImpl<EngineT>::BackgroundTimerTask(int interval) {
+
+void DBImpl::BackgroundTimerTask(int interval) {
     Status status;
     while (true) {
         if (!bg_error_.ok()) break;
@@ -315,22 +320,19 @@ void DBImpl<EngineT>::BackgroundTimerTask(int interval) {
     }
 }
 
-template<typename EngineT>
-void DBImpl<EngineT>::TrySchedule() {
+void DBImpl::TrySchedule() {
     if (bg_compaction_scheduled_) return;
     if (!bg_error_.ok()) return;
 
     bg_compaction_scheduled_ = true;
-    env_->Schedule(&DBImpl<EngineT>::BGWork, this);
+    env_->Schedule(&DBImpl::BGWork, this);
 }
 
-template<typename EngineT>
-void DBImpl<EngineT>::BGWork(void* db_) {
+void DBImpl::BGWork(void* db_) {
     reinterpret_cast<DBImpl*>(db_)->BackgroundCall();
 }
 
-template<typename EngineT>
-void DBImpl<EngineT>::BackgroundCall() {
+void DBImpl::BackgroundCall() {
     std::lock_guard<std::mutex> lock(mutex_);
     assert(bg_compaction_scheduled_);
 
@@ -343,9 +345,7 @@ void DBImpl<EngineT>::BackgroundCall() {
     bg_work_finish_signal_.notify_all();
 }
 
-
-template<typename EngineT>
-Status DBImpl<EngineT>::MergeFiles(const std::string& table_id, const meta::DateT& date,
+Status DBImpl::MergeFiles(const std::string& table_id, const meta::DateT& date,
         const meta::TableFilesSchema& files) {
     meta::TableFileSchema table_file;
     table_file.table_id = table_id;
@@ -357,7 +357,7 @@ Status DBImpl<EngineT>::MergeFiles(const std::string& table_id, const meta::Date
         return status;
     }
 
-    EngineT index(table_file.dimension, table_file.location);
+    ExecutionEnginePtr index = EngineFactory::Build(table_file.dimension, table_file.location, (EngineType)table_file.engine_type_);
 
     meta::TableFilesSchema updated;
     long  index_size = 0;
@@ -365,7 +365,7 @@ Status DBImpl<EngineT>::MergeFiles(const std::string& table_id, const meta::Date
     for (auto& file : files) {
 
         auto start_time = METRICS_NOW_TIME;
-        index.Merge(file.location);
+        index->Merge(file.location);
         auto file_schema = file;
         auto end_time = METRICS_NOW_TIME;
         auto total_time = METRICS_MICROSECONDS(start_time,end_time);
@@ -374,13 +374,13 @@ Status DBImpl<EngineT>::MergeFiles(const std::string& table_id, const meta::Date
         file_schema.file_type = meta::TableFileSchema::TO_DELETE;
         updated.push_back(file_schema);
         LOG(DEBUG) << "Merging file " << file_schema.file_id;
-        index_size = index.Size();
+        index_size = index->Size();
 
         if (index_size >= options_.index_trigger_size) break;
     }
 
 
-    index.Serialize();
+    index->Serialize();
 
     if (index_size >= options_.index_trigger_size) {
         table_file.file_type = meta::TableFileSchema::TO_INDEX;
@@ -391,15 +391,14 @@ Status DBImpl<EngineT>::MergeFiles(const std::string& table_id, const meta::Date
     updated.push_back(table_file);
     status = pMeta_->UpdateTableFiles(updated);
     LOG(DEBUG) << "New merged file " << table_file.file_id <<
-        " of size=" << index.PhysicalSize()/(1024*1024) << " M";
+        " of size=" << index->PhysicalSize()/(1024*1024) << " M";
 
-    index.Cache();
+    index->Cache();
 
     return status;
 }
 
-template<typename EngineT>
-Status DBImpl<EngineT>::BackgroundMergeFiles(const std::string& table_id) {
+Status DBImpl::BackgroundMergeFiles(const std::string& table_id) {
     meta::DatePartionedTableFilesSchema raw_files;
     auto status = pMeta_->FilesToMerge(table_id, raw_files);
     if (!status.ok()) {
@@ -426,8 +425,7 @@ Status DBImpl<EngineT>::BackgroundMergeFiles(const std::string& table_id) {
     return Status::OK();
 }
 
-template<typename EngineT>
-Status DBImpl<EngineT>::BuildIndex(const meta::TableFileSchema& file) {
+Status DBImpl::BuildIndex(const meta::TableFileSchema& file) {
     meta::TableFileSchema table_file;
     table_file.table_id = file.table_id;
     table_file.date = file.date;
@@ -436,11 +434,11 @@ Status DBImpl<EngineT>::BuildIndex(const meta::TableFileSchema& file) {
         return status;
     }
 
-    EngineT to_index(file.dimension, file.location);
+    ExecutionEnginePtr to_index = EngineFactory::Build(file.dimension, file.location, (EngineType)file.engine_type_);
 
-    to_index.Load();
+    to_index->Load();
     auto start_time = METRICS_NOW_TIME;
-    auto index = to_index.BuildIndex(table_file.location);
+    auto index = to_index->BuildIndex(table_file.location);
     auto end_time = METRICS_NOW_TIME;
     auto total_time = METRICS_MICROSECONDS(start_time, end_time);
     server::Metrics::GetInstance().BuildIndexDurationSecondsHistogramObserve(total_time);
@@ -464,8 +462,7 @@ Status DBImpl<EngineT>::BuildIndex(const meta::TableFileSchema& file) {
     return Status::OK();
 }
 
-template<typename EngineT>
-void DBImpl<EngineT>::BackgroundBuildIndex() {
+void DBImpl::BackgroundBuildIndex() {
     std::lock_guard<std::mutex> lock(build_index_mutex_);
     assert(bg_build_index_started_);
     meta::TableFilesSchema to_index_files;
@@ -485,18 +482,16 @@ void DBImpl<EngineT>::BackgroundBuildIndex() {
     bg_build_index_finish_signal_.notify_all();
 }
 
-template<typename EngineT>
-Status DBImpl<EngineT>::TryBuildIndex() {
+Status DBImpl::TryBuildIndex() {
     if (bg_build_index_started_) return Status::OK();
     if (shutting_down_.load(std::memory_order_acquire)) return Status::OK();
     bg_build_index_started_ = true;
-    std::thread build_index_task(&DBImpl<EngineT>::BackgroundBuildIndex, this);
+    std::thread build_index_task(&DBImpl::BackgroundBuildIndex, this);
     build_index_task.detach();
     return Status::OK();
 }
 
-template<typename EngineT>
-void DBImpl<EngineT>::BackgroundCompaction() {
+void DBImpl::BackgroundCompaction() {
     std::vector<std::string> table_ids;
     pMemMgr_->Serialize(table_ids);
 
@@ -510,18 +505,15 @@ void DBImpl<EngineT>::BackgroundCompaction() {
     }
 }
 
-template<typename EngineT>
-Status DBImpl<EngineT>::DropAll() {
+Status DBImpl::DropAll() {
     return pMeta_->DropAll();
 }
 
-template<typename EngineT>
-Status DBImpl<EngineT>::Size(long& result) {
+Status DBImpl::Size(long& result) {
     return  pMeta_->Size(result);
 }
 
-template<typename EngineT>
-DBImpl<EngineT>::~DBImpl() {
+DBImpl::~DBImpl() {
     {
         std::unique_lock<std::mutex> lock(mutex_);
         shutting_down_.store(true, std::memory_order_release);
diff --git a/cpp/src/db/DBImpl.h b/cpp/src/db/DBImpl.h
index b67aa8a0a9ac54176d85150783e509d8202648de..4f9ab54cfbebd4e64e72a262e8fb3ba9bb9d0173 100644
--- a/cpp/src/db/DBImpl.h
+++ b/cpp/src/db/DBImpl.h
@@ -8,12 +8,12 @@
 #include "DB.h"
 #include "MemManager.h"
 #include "Types.h"
-#include "Traits.h"
 
 #include <mutex>
 #include <condition_variable>
 #include <memory>
 #include <atomic>
+#include <thread>
 
 namespace zilliz {
 namespace vecwise {
@@ -25,11 +25,10 @@ namespace meta {
     class Meta;
 }
 
-template <typename EngineT>
 class DBImpl : public DB {
 public:
     using MetaPtr = meta::Meta::Ptr;
-    using MemManagerPtr = typename MemManager<EngineT>::Ptr;
+    using MemManagerPtr = typename MemManager::Ptr;
 
     DBImpl(const Options& options);
 
@@ -100,5 +99,3 @@ private:
 } // namespace engine
 } // namespace vecwise
 } // namespace zilliz
-
-#include "DBImpl.inl"
diff --git a/cpp/src/db/DBMetaImpl.cpp b/cpp/src/db/DBMetaImpl.cpp
index ea325c0c54c6227a2591135d70163944387c4a36..9eab7b07aa2c8d3df7fd7e4c19bcf89beef1d589 100644
--- a/cpp/src/db/DBMetaImpl.cpp
+++ b/cpp/src/db/DBMetaImpl.cpp
@@ -7,6 +7,7 @@
 #include "IDGenerator.h"
 #include "Utils.h"
 #include "MetaConsts.h"
+#include "Factories.h"
 #include "metrics/Metrics.h"
 
 #include <unistd.h>
@@ -33,10 +34,12 @@ inline auto StoragePrototype(const std::string &path) {
                                    make_column("table_id", &TableSchema::table_id, unique()),
                                    make_column("dimension", &TableSchema::dimension),
                                    make_column("created_on", &TableSchema::created_on),
-                                   make_column("files_cnt", &TableSchema::files_cnt, default_value(0))),
+                                   make_column("files_cnt", &TableSchema::files_cnt, default_value(0)),
+                                   make_column("engine_type", &TableSchema::engine_type_)),
                         make_table("TableFile",
                                    make_column("id", &TableFileSchema::id, primary_key()),
                                    make_column("table_id", &TableFileSchema::table_id),
+                                   make_column("engine_type", &TableFileSchema::engine_type_),
                                    make_column("file_id", &TableFileSchema::file_id),
                                    make_column("file_type", &TableFileSchema::file_type),
                                    make_column("size", &TableFileSchema::size, default_value(0)),
diff --git a/cpp/src/db/EngineFactory.cpp b/cpp/src/db/EngineFactory.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..a9b0bc744d4d21558195e0a1c6b56fea3baa20b5
--- /dev/null
+++ b/cpp/src/db/EngineFactory.cpp
@@ -0,0 +1,31 @@
+/*******************************************************************************
+ * Copyright 上海赜睿信息科技有限公司(Zilliz) - All Rights Reserved
+ * Unauthorized copying of this file, via any medium is strictly prohibited.
+ * Proprietary and confidential.
+ ******************************************************************************/
+#include "EngineFactory.h"
+#include "FaissExecutionEngine.h"
+#include "Log.h"
+
+namespace zilliz {
+namespace vecwise {
+namespace engine {
+
+ExecutionEnginePtr
+EngineFactory::Build(uint16_t dimension,
+        const std::string& location,
+        EngineType type) {
+    switch(type) {
+        case EngineType::FAISS_IDMAP:
+            return ExecutionEnginePtr(new FaissExecutionEngine(dimension, location, "IDMap", "IDMap,Flat"));
+        case EngineType::FAISS_IVFFLAT:
+            return ExecutionEnginePtr(new FaissExecutionEngine(dimension, location, "IVF", "IDMap,Flat"));
+        default:
+            ENGINE_LOG_ERROR << "Unsupportted engine type";
+            return nullptr;
+    }
+}
+
+}
+}
+}
\ No newline at end of file
diff --git a/cpp/src/db/Traits.h b/cpp/src/db/EngineFactory.h
similarity index 61%
rename from cpp/src/db/Traits.h
rename to cpp/src/db/EngineFactory.h
index 1740bc87ed6e821f36b0add1a282ba3a62b5b591..fe984d70cd52b80c36ecfeecb15669888c132f15 100644
--- a/cpp/src/db/Traits.h
+++ b/cpp/src/db/EngineFactory.h
@@ -5,22 +5,20 @@
  ******************************************************************************/
 #pragma once
 
+#include "Status.h"
+#include "ExecutionEngine.h"
 
 namespace zilliz {
 namespace vecwise {
 namespace engine {
 
-struct IVFIndexTrait {
-    static const char* BuildIndexType;
-    static const char* RawIndexType;
+class EngineFactory {
+public:
+    static ExecutionEnginePtr Build(uint16_t dimension,
+                                    const std::string& location,
+                                    EngineType type);
 };
 
-struct IDMapIndexTrait {
-    static const char* BuildIndexType;
-    static const char* RawIndexType;
-};
-
-
-} // namespace engine
-} // namespace vecwise
-} // namespace zilliz
+}
+}
+}
diff --git a/cpp/src/db/ExecutionEngine.cpp b/cpp/src/db/ExecutionEngine.cpp
index 6eb04bb788e17dc403c49975c760a369efb9b8d9..54349b7b69ff436b1677560f50a378f25eff76d5 100644
--- a/cpp/src/db/ExecutionEngine.cpp
+++ b/cpp/src/db/ExecutionEngine.cpp
@@ -11,8 +11,7 @@ namespace zilliz {
 namespace vecwise {
 namespace engine {
 
-template<typename Derived>
-Status ExecutionEngine<Derived>::AddWithIds(const std::vector<float>& vectors, const std::vector<long>& vector_ids) {
+Status ExecutionEngine::AddWithIds(const std::vector<float>& vectors, const std::vector<long>& vector_ids) {
     long n1 = (long)vectors.size();
     long n2 = (long)vector_ids.size();
     if (n1 != n2) {
@@ -22,60 +21,6 @@ Status ExecutionEngine<Derived>::AddWithIds(const std::vector<float>& vectors, c
     return AddWithIds(n1, vectors.data(), vector_ids.data());
 }
 
-template<typename Derived>
-Status ExecutionEngine<Derived>::AddWithIds(long n, const float *xdata, const long *xids) {
-    return static_cast<Derived*>(this)->AddWithIds(n, xdata, xids);
-}
-
-template<typename Derived>
-size_t ExecutionEngine<Derived>::Count() const {
-    return static_cast<Derived*>(this)->Count();
-}
-
-template<typename Derived>
-size_t ExecutionEngine<Derived>::Size() const {
-    return static_cast<Derived*>(this)->Size();
-}
-
-template<typename Derived>
-size_t ExecutionEngine<Derived>::PhysicalSize() const {
-    return static_cast<Derived*>(this)->PhysicalSize();
-}
-
-template<typename Derived>
-Status ExecutionEngine<Derived>::Serialize() {
-    return static_cast<Derived*>(this)->Serialize();
-}
-
-template<typename Derived>
-Status ExecutionEngine<Derived>::Load() {
-    return static_cast<Derived*>(this)->Load();
-}
-
-template<typename Derived>
-Status ExecutionEngine<Derived>::Merge(const std::string& location) {
-    return static_cast<Derived*>(this)->Merge(location);
-}
-
-template<typename Derived>
-Status ExecutionEngine<Derived>::Search(long n,
-                          const float *data,
-                          long k,
-                          float *distances,
-                          long *labels) const {
-    return static_cast<Derived*>(this)->Search(n, data, k, distances, labels);
-}
-
-template<typename Derived>
-Status ExecutionEngine<Derived>::Cache() {
-    return static_cast<Derived*>(this)->Cache();
-}
-
-template<typename Derived>
-std::shared_ptr<Derived> ExecutionEngine<Derived>::BuildIndex(const std::string& location) {
-    return static_cast<Derived*>(this)->BuildIndex(location);
-}
-
 
 } // namespace engine
 } // namespace vecwise
diff --git a/cpp/src/db/ExecutionEngine.h b/cpp/src/db/ExecutionEngine.h
index 6ad91959e8fe8c95a5f8e0d32ef2b098525b993b..0773e4a837db8ef335d307b9b27f98a8f7bf80eb 100644
--- a/cpp/src/db/ExecutionEngine.h
+++ b/cpp/src/db/ExecutionEngine.h
@@ -14,38 +14,44 @@ namespace zilliz {
 namespace vecwise {
 namespace engine {
 
-template <typename Derived>
+enum class EngineType {
+    FAISS_IDMAP = 1,
+    FAISS_IVFFLAT,
+};
+
 class ExecutionEngine {
 public:
 
-    Status AddWithIds(const std::vector<float>& vectors,
-                              const std::vector<long>& vector_ids);
+    virtual Status AddWithIds(const std::vector<float>& vectors,
+            const std::vector<long>& vector_ids);
 
-    Status AddWithIds(long n, const float *xdata, const long *xids);
+    virtual Status AddWithIds(long n, const float *xdata, const long *xids) = 0;
 
-    size_t Count() const;
+    virtual size_t Count() const = 0;
 
-    size_t Size() const;
+    virtual size_t Size() const = 0;
 
-    size_t PhysicalSize() const;
+    virtual size_t PhysicalSize() const = 0;
 
-    Status Serialize();
+    virtual Status Serialize() = 0;
 
-    Status Load();
+    virtual Status Load() = 0;
 
-    Status Merge(const std::string& location);
+    virtual Status Merge(const std::string& location) = 0;
 
-    Status Search(long n,
+    virtual Status Search(long n,
                   const float *data,
                   long k,
                   float *distances,
-                  long *labels) const;
+                  long *labels) const = 0;
 
-    std::shared_ptr<Derived> BuildIndex(const std::string&);
+    virtual std::shared_ptr<ExecutionEngine> BuildIndex(const std::string&) = 0;
 
-    Status Cache();
+    virtual Status Cache() = 0;
 };
 
+using ExecutionEnginePtr = std::shared_ptr<ExecutionEngine>;
+
 
 } // namespace engine
 } // namespace vecwise
diff --git a/cpp/src/db/Factories.cpp b/cpp/src/db/Factories.cpp
index 191d3dbae5f04ca722143a71e5b274b2534389c9..bbaa17343b8738cfd306c19dd1d86f619671676c 100644
--- a/cpp/src/db/Factories.cpp
+++ b/cpp/src/db/Factories.cpp
@@ -5,8 +5,6 @@
 ////////////////////////////////////////////////////////////////////////////////
 #include "Factories.h"
 #include "DBImpl.h"
-#include "FaissExecutionEngine.h"
-#include "Traits.h"
 
 #include <stdlib.h>
 #include <time.h>
@@ -45,28 +43,14 @@ std::shared_ptr<meta::DBMetaImpl> DBMetaImplFactory::Build() {
     return std::shared_ptr<meta::DBMetaImpl>(new meta::DBMetaImpl(options));
 }
 
-std::shared_ptr<DB> DBFactory::Build(const std::string& db_type) {
+std::shared_ptr<DB> DBFactory::Build() {
     auto options = OptionsFactory::Build();
-    auto db = DBFactory::Build(options, db_type);
+    auto db = DBFactory::Build(options);
     return std::shared_ptr<DB>(db);
 }
 
-DB* DBFactory::Build(const Options& options, const std::string& db_type) {
-    std::stringstream ss(db_type);
-    std::string token;
-    std::vector<std::string> tokens;
-    while (std::getline(ss, token, ',')) {
-        tokens.push_back(token);
-    }
-
-    assert(tokens.size()==2);
-    assert(tokens[0]=="Faiss");
-    if (tokens[1] == "IVF") {
-        return new DBImpl<FaissExecutionEngine<IVFIndexTrait>>(options);
-    } else if (tokens[1] == "IDMap") {
-        return new DBImpl<FaissExecutionEngine<IDMapIndexTrait>>(options);
-    }
-    return nullptr;
+DB* DBFactory::Build(const Options& options) {
+    return new DBImpl(options);
 }
 
 } // namespace engine
diff --git a/cpp/src/db/Factories.h b/cpp/src/db/Factories.h
index 0e9ab71bb12edb5719288875be52a23ab43a3e02..9bcd3ffb6776f28b97b8727aa9ffe9ad1c83a153 100644
--- a/cpp/src/db/Factories.h
+++ b/cpp/src/db/Factories.h
@@ -8,6 +8,7 @@
 #include "DB.h"
 #include "DBMetaImpl.h"
 #include "Options.h"
+#include "ExecutionEngine.h"
 
 #include <string>
 #include <memory>
@@ -29,8 +30,8 @@ struct DBMetaImplFactory {
 };
 
 struct DBFactory {
-    static std::shared_ptr<DB> Build(const std::string& db_type = "Faiss,IVF");
-    static DB* Build(const Options&, const std::string& db_type = "Faiss,IVF");
+    static std::shared_ptr<DB> Build();
+    static DB* Build(const Options&);
 };
 
 } // namespace engine
diff --git a/cpp/src/db/FaissExecutionEngine.inl b/cpp/src/db/FaissExecutionEngine.cpp
similarity index 69%
rename from cpp/src/db/FaissExecutionEngine.inl
rename to cpp/src/db/FaissExecutionEngine.cpp
index 8dd701d54df474333197b17da3201e1b5736e143..a338ddf5cbb910f0f43febe737f59fc130cec582 100644
--- a/cpp/src/db/FaissExecutionEngine.inl
+++ b/cpp/src/db/FaissExecutionEngine.cpp
@@ -3,8 +3,6 @@
  * Unauthorized copying of this file, via any medium is strictly prohibited.
  * Proprietary and confidential.
  ******************************************************************************/
-#pragma once
-
 #include "FaissExecutionEngine.h"
 
 #include <easylogging++.h>
@@ -23,47 +21,49 @@ namespace vecwise {
 namespace engine {
 
 
-template<class IndexTrait>
-FaissExecutionEngine<IndexTrait>::FaissExecutionEngine(uint16_t dimension, const std::string& location)
-    : pIndex_(faiss::index_factory(dimension, IndexTrait::RawIndexType)),
-      location_(location) {
+FaissExecutionEngine::FaissExecutionEngine(uint16_t dimension,
+        const std::string& location,
+        const std::string& build_index_type,
+        const std::string& raw_index_type)
+    : pIndex_(faiss::index_factory(dimension, raw_index_type.c_str())),
+      location_(location),
+      build_index_type_(build_index_type),
+      raw_index_type_(raw_index_type) {
 }
 
-template<class IndexTrait>
-FaissExecutionEngine<IndexTrait>::FaissExecutionEngine(std::shared_ptr<faiss::Index> index, const std::string& location)
+FaissExecutionEngine::FaissExecutionEngine(std::shared_ptr<faiss::Index> index,
+        const std::string& location,
+        const std::string& build_index_type,
+        const std::string& raw_index_type)
     : pIndex_(index),
-      location_(location) {
+      location_(location),
+      build_index_type_(build_index_type),
+      raw_index_type_(raw_index_type) {
 }
 
-template<class IndexTrait>
-Status FaissExecutionEngine<IndexTrait>::AddWithIds(long n, const float *xdata, const long *xids) {
+Status FaissExecutionEngine::AddWithIds(long n, const float *xdata, const long *xids) {
     pIndex_->add_with_ids(n, xdata, xids);
     return Status::OK();
 }
 
-template<class IndexTrait>
-size_t FaissExecutionEngine<IndexTrait>::Count() const {
+size_t FaissExecutionEngine::Count() const {
     return (size_t)(pIndex_->ntotal);
 }
 
-template<class IndexTrait>
-size_t FaissExecutionEngine<IndexTrait>::Size() const {
+size_t FaissExecutionEngine::Size() const {
     return (size_t)(Count() * pIndex_->d)*sizeof(float);
 }
 
-template<class IndexTrait>
-size_t FaissExecutionEngine<IndexTrait>::PhysicalSize() const {
+size_t FaissExecutionEngine::PhysicalSize() const {
     return (size_t)(Count() * pIndex_->d)*sizeof(float);
 }
 
-template<class IndexTrait>
-Status FaissExecutionEngine<IndexTrait>::Serialize() {
+Status FaissExecutionEngine::Serialize() {
     write_index(pIndex_.get(), location_.c_str());
     return Status::OK();
 }
 
-template<class IndexTrait>
-Status FaissExecutionEngine<IndexTrait>::Load() {
+Status FaissExecutionEngine::Load() {
     auto index  = zilliz::vecwise::cache::CpuCacheMgr::GetInstance()->GetIndex(location_);
     bool to_cache = false;
     auto start_time = METRICS_NOW_TIME;
@@ -90,8 +90,7 @@ Status FaissExecutionEngine<IndexTrait>::Load() {
     return Status::OK();
 }
 
-template<class IndexTrait>
-Status FaissExecutionEngine<IndexTrait>::Merge(const std::string& location) {
+Status FaissExecutionEngine::Merge(const std::string& location) {
     if (location == location_) {
         return Status::Error("Cannot Merge Self");
     }
@@ -105,12 +104,11 @@ Status FaissExecutionEngine<IndexTrait>::Merge(const std::string& location) {
     return Status::OK();
 }
 
-template<class IndexTrait>
-typename FaissExecutionEngine<IndexTrait>::Ptr
-FaissExecutionEngine<IndexTrait>::BuildIndex(const std::string& location) {
+ExecutionEnginePtr
+FaissExecutionEngine::BuildIndex(const std::string& location) {
     auto opd = std::make_shared<Operand>();
     opd->d = pIndex_->d;
-    opd->index_type = IndexTrait::BuildIndexType;
+    opd->index_type = build_index_type_;
     IndexBuilderPtr pBuilder = GetIndexBuilder(opd);
 
     auto from_index = dynamic_cast<faiss::IndexIDMap*>(pIndex_.get());
@@ -119,13 +117,12 @@ FaissExecutionEngine<IndexTrait>::BuildIndex(const std::string& location) {
             dynamic_cast<faiss::IndexFlat*>(from_index->index)->xb.data(),
             from_index->id_map.data());
 
-    Ptr new_ee(new FaissExecutionEngine<IndexTrait>(index->data(), location));
+    ExecutionEnginePtr new_ee(new FaissExecutionEngine(index->data(), location, build_index_type_, raw_index_type_));
     new_ee->Serialize();
     return new_ee;
 }
 
-template<class IndexTrait>
-Status FaissExecutionEngine<IndexTrait>::Search(long n,
+Status FaissExecutionEngine::Search(long n,
                                     const float *data,
                                     long k,
                                     float *distances,
@@ -135,8 +132,7 @@ Status FaissExecutionEngine<IndexTrait>::Search(long n,
     return Status::OK();
 }
 
-template<class IndexTrait>
-Status FaissExecutionEngine<IndexTrait>::Cache() {
+Status FaissExecutionEngine::Cache() {
     zilliz::vecwise::cache::CpuCacheMgr::GetInstance(
             )->InsertItem(location_, std::make_shared<Index>(pIndex_));
 
diff --git a/cpp/src/db/FaissExecutionEngine.h b/cpp/src/db/FaissExecutionEngine.h
index 2915acc0ebc7325dc790f03441bc6b3e30c3be2f..d1981502b9e25a30ed6849b4f6c1f637e918fd9e 100644
--- a/cpp/src/db/FaissExecutionEngine.h
+++ b/cpp/src/db/FaissExecutionEngine.h
@@ -19,50 +19,52 @@ namespace vecwise {
 namespace engine {
 
 
-template<class IndexTrait>
-class FaissExecutionEngine : public ExecutionEngine<FaissExecutionEngine<IndexTrait>> {
+class FaissExecutionEngine : public ExecutionEngine {
 public:
-    using Ptr = std::shared_ptr<FaissExecutionEngine<IndexTrait>>;
 
-    FaissExecutionEngine(uint16_t dimension, const std::string& location);
-    FaissExecutionEngine(std::shared_ptr<faiss::Index> index, const std::string& location);
+    FaissExecutionEngine(uint16_t dimension,
+            const std::string& location,
+            const std::string& build_index_type,
+            const std::string& raw_index_type);
 
-    Status AddWithIds(const std::vector<float>& vectors,
-                              const std::vector<long>& vector_ids);
+    FaissExecutionEngine(std::shared_ptr<faiss::Index> index,
+            const std::string& location,
+            const std::string& build_index_type,
+            const std::string& raw_index_type);
 
-    Status AddWithIds(long n, const float *xdata, const long *xids);
+    Status AddWithIds(long n, const float *xdata, const long *xids) override;
 
-    size_t Count() const;
+    size_t Count() const override;
 
-    size_t Size() const;
+    size_t Size() const override;
 
-    size_t PhysicalSize() const;
+    size_t PhysicalSize() const override;
 
-    Status Serialize();
+    Status Serialize() override;
 
-    Status Load();
+    Status Load() override;
 
-    Status Merge(const std::string& location);
+    Status Merge(const std::string& location) override;
 
     Status Search(long n,
                   const float *data,
                   long k,
                   float *distances,
-                  long *labels) const;
+                  long *labels) const override;
 
-    Ptr BuildIndex(const std::string&);
+    ExecutionEnginePtr BuildIndex(const std::string&) override;
 
-    Status Cache();
+    Status Cache() override;
 
 protected:
-
     std::shared_ptr<faiss::Index> pIndex_;
     std::string location_;
+
+    std::string build_index_type_;
+    std::string raw_index_type_;
 };
 
 
 } // namespace engine
 } // namespace vecwise
 } // namespace zilliz
-
-#include "FaissExecutionEngine.inl"
diff --git a/cpp/src/db/Log.h b/cpp/src/db/Log.h
new file mode 100644
index 0000000000000000000000000000000000000000..1e938591a0697105f3a257bbc095159295744512
--- /dev/null
+++ b/cpp/src/db/Log.h
@@ -0,0 +1,26 @@
+/*******************************************************************************
+ * Copyright 上海赜睿信息科技有限公司(Zilliz) - All Rights Reserved
+ * Unauthorized copying of this file, via any medium is strictly prohibited.
+ * Proprietary and confidential.
+ ******************************************************************************/
+#pragma once
+
+#include <easylogging++.h>
+
+namespace zilliz {
+namespace vecwise {
+namespace engine {
+
+#define ENGINE_DOMAIN_NAME "[ENGINE] "
+#define ENGINE_ERROR_TEXT "ENGINE Error:"
+
+#define ENGINE_LOG_TRACE LOG(TRACE) << ENGINE_DOMAIN_NAME
+#define ENGINE_LOG_DEBUG LOG(DEBUG) << ENGINE_DOMAIN_NAME
+#define ENGINE_LOG_INFO LOG(INFO) << ENGINE_DOMAIN_NAME
+#define ENGINE_LOG_WARNING LOG(WARNING) << ENGINE_DOMAIN_NAME
+#define ENGINE_LOG_ERROR LOG(ERROR) << ENGINE_DOMAIN_NAME
+#define ENGINE_LOG_FATAL LOG(FATAL) << ENGINE_DOMAIN_NAME
+
+} // namespace sql
+} // namespace zilliz
+} // namespace server
diff --git a/cpp/src/db/MemManager.inl b/cpp/src/db/MemManager.cpp
similarity index 73%
rename from cpp/src/db/MemManager.inl
rename to cpp/src/db/MemManager.cpp
index 528622795de8f8c29227bdeded2232bf07ad2b4e..c8b9e0fd5ae2a9d8d8e85917a8c54c7f096900a3 100644
--- a/cpp/src/db/MemManager.inl
+++ b/cpp/src/db/MemManager.cpp
@@ -3,11 +3,10 @@
  * Unauthorized copying of this file, via any medium is strictly prohibited.
  * Proprietary and confidential.
  ******************************************************************************/
-#pragma once
-
 #include "MemManager.h"
 #include "Meta.h"
 #include "MetaConsts.h"
+#include "EngineFactory.h"
 #include "metrics/Metrics.h"
 
 #include <iostream>
@@ -19,34 +18,29 @@ namespace zilliz {
 namespace vecwise {
 namespace engine {
 
-template<typename EngineT>
-MemVectors<EngineT>::MemVectors(const std::shared_ptr<meta::Meta>& meta_ptr,
+MemVectors::MemVectors(const std::shared_ptr<meta::Meta>& meta_ptr,
         const meta::TableFileSchema& schema, const Options& options)
   : pMeta_(meta_ptr),
     options_(options),
     schema_(schema),
     pIdGenerator_(new SimpleIDGenerator()),
-    pEE_(new EngineT(schema_.dimension, schema_.location)) {
+    pEE_(EngineFactory::Build(schema_.dimension, schema_.location, (EngineType)schema_.engine_type_)) {
 }
 
-template<typename EngineT>
-void MemVectors<EngineT>::Add(size_t n_, const float* vectors_, IDNumbers& vector_ids_) {
+void MemVectors::Add(size_t n_, const float* vectors_, IDNumbers& vector_ids_) {
     pIdGenerator_->GetNextIDNumbers(n_, vector_ids_);
     pEE_->AddWithIds(n_, vectors_, vector_ids_.data());
 }
 
-template<typename EngineT>
-size_t MemVectors<EngineT>::Total() const {
+size_t MemVectors::Total() const {
     return pEE_->Count();
 }
 
-template<typename EngineT>
-size_t MemVectors<EngineT>::ApproximateSize() const {
+size_t MemVectors::ApproximateSize() const {
     return pEE_->Size();
 }
 
-template<typename EngineT>
-Status MemVectors<EngineT>::Serialize(std::string& table_id) {
+Status MemVectors::Serialize(std::string& table_id) {
     table_id = schema_.table_id;
     auto size = ApproximateSize();
     auto start_time = METRICS_NOW_TIME;
@@ -70,8 +64,7 @@ Status MemVectors<EngineT>::Serialize(std::string& table_id) {
     return status;
 }
 
-template<typename EngineT>
-MemVectors<EngineT>::~MemVectors() {
+MemVectors::~MemVectors() {
     if (pIdGenerator_ != nullptr) {
         delete pIdGenerator_;
         pIdGenerator_ = nullptr;
@@ -81,9 +74,7 @@ MemVectors<EngineT>::~MemVectors() {
 /*
  * MemManager
  */
-
-template<typename EngineT>
-typename MemManager<EngineT>::MemVectorsPtr MemManager<EngineT>::GetMemByTable(
+MemManager::MemVectorsPtr MemManager::GetMemByTable(
         const std::string& table_id) {
     auto memIt = memMap_.find(table_id);
     if (memIt != memMap_.end()) {
@@ -97,12 +88,11 @@ typename MemManager<EngineT>::MemVectorsPtr MemManager<EngineT>::GetMemByTable(
         return nullptr;
     }
 
-    memMap_[table_id] = MemVectorsPtr(new MemVectors<EngineT>(pMeta_, table_file, options_));
+    memMap_[table_id] = MemVectorsPtr(new MemVectors(pMeta_, table_file, options_));
     return memMap_[table_id];
 }
 
-template<typename EngineT>
-Status MemManager<EngineT>::InsertVectors(const std::string& table_id_,
+Status MemManager::InsertVectors(const std::string& table_id_,
         size_t n_,
         const float* vectors_,
         IDNumbers& vector_ids_) {
@@ -110,8 +100,7 @@ Status MemManager<EngineT>::InsertVectors(const std::string& table_id_,
     return InsertVectorsNoLock(table_id_, n_, vectors_, vector_ids_);
 }
 
-template<typename EngineT>
-Status MemManager<EngineT>::InsertVectorsNoLock(const std::string& table_id,
+Status MemManager::InsertVectorsNoLock(const std::string& table_id,
         size_t n,
         const float* vectors,
         IDNumbers& vector_ids) {
@@ -124,8 +113,7 @@ Status MemManager<EngineT>::InsertVectorsNoLock(const std::string& table_id,
     return Status::OK();
 }
 
-template<typename EngineT>
-Status MemManager<EngineT>::ToImmutable() {
+Status MemManager::ToImmutable() {
     std::unique_lock<std::mutex> lock(mutex_);
     for (auto& kv: memMap_) {
         immMems_.push_back(kv.second);
@@ -135,8 +123,7 @@ Status MemManager<EngineT>::ToImmutable() {
     return Status::OK();
 }
 
-template<typename EngineT>
-Status MemManager<EngineT>::Serialize(std::vector<std::string>& table_ids) {
+Status MemManager::Serialize(std::vector<std::string>& table_ids) {
     ToImmutable();
     std::unique_lock<std::mutex> lock(serialization_mtx_);
     std::string table_id;
diff --git a/cpp/src/db/MemManager.h b/cpp/src/db/MemManager.h
index 35272f4211d32e4340ad8252e9a0f963e21c1432..2503b6fb9856a17703a70c2b7093b99206cc6ba7 100644
--- a/cpp/src/db/MemManager.h
+++ b/cpp/src/db/MemManager.h
@@ -5,6 +5,7 @@
  ******************************************************************************/
 #pragma once
 
+#include "ExecutionEngine.h"
 #include "IDGenerator.h"
 #include "Status.h"
 #include "Meta.h"
@@ -23,12 +24,10 @@ namespace meta {
     class Meta;
 }
 
-template <typename EngineT>
 class MemVectors {
 public:
-    using EnginePtr = typename EngineT::Ptr;
     using MetaPtr = meta::Meta::Ptr;
-    using Ptr = std::shared_ptr<MemVectors<EngineT>>;
+    using Ptr = std::shared_ptr<MemVectors>;
 
     explicit MemVectors(const std::shared_ptr<meta::Meta>&,
             const meta::TableFileSchema&, const Options&);
@@ -54,18 +53,17 @@ private:
     Options options_;
     meta::TableFileSchema schema_;
     IDGenerator* pIdGenerator_;
-    EnginePtr pEE_;
+    ExecutionEnginePtr pEE_;
 
 }; // MemVectors
 
 
 
-template<typename EngineT>
 class MemManager {
 public:
     using MetaPtr = meta::Meta::Ptr;
-    using MemVectorsPtr = typename MemVectors<EngineT>::Ptr;
-    using Ptr = std::shared_ptr<MemManager<EngineT>>;
+    using MemVectorsPtr = typename MemVectors::Ptr;
+    using Ptr = std::shared_ptr<MemManager>;
 
     MemManager(const std::shared_ptr<meta::Meta>& meta, const Options& options)
         : pMeta_(meta), options_(options) {}
@@ -96,4 +94,3 @@ private:
 } // namespace engine
 } // namespace vecwise
 } // namespace zilliz
-#include "MemManager.inl"
diff --git a/cpp/src/db/MetaTypes.h b/cpp/src/db/MetaTypes.h
index b2fe7833236df885e28d16e4c7d1ac39f7298738..ca110be1a5d142c7518a02e4563055cc8c1ede8b 100644
--- a/cpp/src/db/MetaTypes.h
+++ b/cpp/src/db/MetaTypes.h
@@ -5,6 +5,8 @@
  ******************************************************************************/
 #pragma once
 
+#include "ExecutionEngine.h"
+
 #include <vector>
 #include <map>
 #include <string>
@@ -25,6 +27,7 @@ struct TableSchema {
     uint16_t dimension;
     std::string location;
     long created_on;
+    int engine_type_ = (int)EngineType::FAISS_IDMAP;
 }; // TableSchema
 
 struct TableFileSchema {
@@ -38,6 +41,7 @@ struct TableFileSchema {
 
     size_t id;
     std::string table_id;
+    int engine_type_ = (int)EngineType::FAISS_IDMAP;
     std::string file_id;
     int file_type = NEW;
     size_t size;
diff --git a/cpp/src/db/Traits.cpp b/cpp/src/db/Traits.cpp
deleted file mode 100644
index a30b9fc036cfb4c7e02ee6e9b79799577d07ec5d..0000000000000000000000000000000000000000
--- a/cpp/src/db/Traits.cpp
+++ /dev/null
@@ -1,20 +0,0 @@
-/*******************************************************************************
- * Copyright 上海赜睿信息科技有限公司(Zilliz) - All Rights Reserved
- * Unauthorized copying of this file, via any medium is strictly prohibited.
- * Proprietary and confidential.
- ******************************************************************************/
-#include "Traits.h"
-
-namespace zilliz {
-namespace vecwise {
-namespace engine {
-
-const char* IVFIndexTrait::BuildIndexType = "IVF";
-const char* IVFIndexTrait::RawIndexType = "IDMap,Flat";
-
-const char* IDMapIndexTrait::BuildIndexType = "IDMap";
-const char* IDMapIndexTrait::RawIndexType = "IDMap,Flat";
-
-} // namespace engine
-} // namespace vecwise
-} // namespace zilliz
diff --git a/cpp/src/db/scheduler/SearchScheduler.cpp b/cpp/src/db/scheduler/SearchScheduler.cpp
index 4d3a12fdf81b670de21c4fa0640194b721991668..9309b131e62baa3ccd6e725acff84806fe329fa2 100644
--- a/cpp/src/db/scheduler/SearchScheduler.cpp
+++ b/cpp/src/db/scheduler/SearchScheduler.cpp
@@ -10,6 +10,7 @@
 #include "utils/Log.h"
 #include "utils/TimeRecorder.h"
 #include "metrics/Metrics.h"
+#include "db/EngineFactory.h"
 
 namespace zilliz {
 namespace vecwise {
@@ -79,7 +80,9 @@ SearchScheduler::IndexLoadWorker() {
 
         server::TimeRecorder rc("Load index");
         //load index
-        IndexEnginePtr index_ptr = std::make_shared<IndexClass>(context->file_->dimension, context->file_->location);
+        ExecutionEnginePtr index_ptr = EngineFactory::Build(context->file_->dimension,
+                context->file_->location,
+                (EngineType)context->file_->engine_type_);
         index_ptr->Load();
 
         rc.Record("load index file to memory");
@@ -111,7 +114,7 @@ SearchScheduler::IndexLoadWorker() {
         }
 
         //put search task to another queue
-        SearchTaskPtr task_ptr = std::make_shared<SearchTaskClass>();
+        SearchTaskPtr task_ptr = std::make_shared<SearchTask>();
         task_ptr->index_id_ = context->file_->id;
         task_ptr->index_type_ = context->file_->file_type;
         task_ptr->index_engine_ = index_ptr;
diff --git a/cpp/src/db/scheduler/SearchTaskQueue.inl b/cpp/src/db/scheduler/SearchTaskQueue.cpp
similarity index 97%
rename from cpp/src/db/scheduler/SearchTaskQueue.inl
rename to cpp/src/db/scheduler/SearchTaskQueue.cpp
index 7816ba8878ce05dbd85efa63582acac07088d4a1..86478477d1f2008c0bb04ac2934f1f55cbe57a34 100644
--- a/cpp/src/db/scheduler/SearchTaskQueue.inl
+++ b/cpp/src/db/scheduler/SearchTaskQueue.cpp
@@ -3,8 +3,6 @@
  * Unauthorized copying of this file, via any medium is strictly prohibited.
  * Proprietary and confidential.
  ******************************************************************************/
-#pragma once
-
 #include "SearchTaskQueue.h"
 #include "utils/Log.h"
 #include "utils/TimeRecorder.h"
@@ -70,8 +68,7 @@ SearchTaskQueue::GetInstance() {
     return instance;
 }
 
-template<typename trait>
-bool SearchTask<trait>::DoSearch() {
+bool SearchTask::DoSearch() {
     if(index_engine_ == nullptr) {
         return false;
     }
diff --git a/cpp/src/db/scheduler/SearchTaskQueue.h b/cpp/src/db/scheduler/SearchTaskQueue.h
index 3b58294811e1de0dc8bd5e9247872373940a9cb1..bd8e9d7f245859d16d9720ce92ed29b772f48349 100644
--- a/cpp/src/db/scheduler/SearchTaskQueue.h
+++ b/cpp/src/db/scheduler/SearchTaskQueue.h
@@ -7,8 +7,7 @@
 
 #include "SearchContext.h"
 #include "utils/BlockingQueue.h"
-#include "../FaissExecutionEngine.h"
-#include "../Traits.h"
+#include "db/ExecutionEngine.h"
 
 #include <memory>
 
@@ -16,16 +15,6 @@ namespace zilliz {
 namespace vecwise {
 namespace engine {
 
-#ifdef GPU_VERSION
-using IndexTraitClass = IVFIndexTrait;
-#else
-using IndexTraitClass = IDMapIndexTrait;
-#endif
-
-using IndexClass = FaissExecutionEngine<IndexTraitClass>;
-using IndexEnginePtr = std::shared_ptr<IndexClass>;
-
-template <typename trait>
 class SearchTask {
 public:
     bool DoSearch();
@@ -33,12 +22,11 @@ public:
 public:
     size_t index_id_ = 0;
     int index_type_ = 0; //for metrics
-    IndexEnginePtr index_engine_;
+    ExecutionEnginePtr index_engine_;
     std::vector<SearchContextPtr> search_contexts_;
 };
 
-using SearchTaskClass = SearchTask<IndexTraitClass>;
-using SearchTaskPtr = std::shared_ptr<SearchTaskClass>;
+using SearchTaskPtr = std::shared_ptr<SearchTask>;
 
 class SearchTaskQueue : public server::BlockingQueue<SearchTaskPtr> {
 private:
@@ -58,6 +46,4 @@ private:
 
 }
 }
-}
-
-#include "SearchTaskQueue.inl"
\ No newline at end of file
+}
\ No newline at end of file
diff --git a/cpp/unittest/db/utils.cpp b/cpp/unittest/db/utils.cpp
index aa3ea560f3d2228aca0ec3535724c743f6bfb808..3e7c588ef6dcebf7338841d1fced9f7539b129bc 100644
--- a/cpp/unittest/db/utils.cpp
+++ b/cpp/unittest/db/utils.cpp
@@ -38,7 +38,7 @@ engine::Options DBTest::GetOptions() {
 void DBTest::SetUp() {
     InitLog();
     auto options = GetOptions();
-    db_ = engine::DBFactory::Build(options, "Faiss,IDMap");
+    db_ = engine::DBFactory::Build(options);
 }
 
 void DBTest::TearDown() {