fix flat search doesn't use gpu bug

CHANGELOG.md

@@ -6,6 +6,7 @@ Please mark all change in change log and use the ticket from JIRA.
 ## Bug
 - \#246 - Exclude src/external folder from code coverage for jenkin ci
 - \#248 - Reside src/external in thirdparty
+- \#327 - Search does not use GPU when index type is FLAT
 
 ## Feature
 - \#12 - Pure CPU version for Milvus

core/src/scheduler/optimizer/OnlyGPUPass.cpp

@@ -34,7 +34,8 @@ OnlyGPUPass::Run(const TaskPtr& task) {
 
     auto search_task = std::static_pointer_cast<XSearchTask>(task);
     if (search_task->file_->engine_type_ != (int)engine::EngineType::FAISS_IVFSQ8 &&
-        search_task->file_->engine_type_ != (int)engine::EngineType::FAISS_IVFFLAT) {
+        search_task->file_->engine_type_ != (int)engine::EngineType::FAISS_IVFFLAT &&
+        search_task->file_->engine_type_ != (int)engine::EngineType::FAISS_IDMAP) {
         return false;
     }