Use named OpContext trace span guard

Signed-off-by: jamesgao-jpg <james.gao@zilliz.com>

Author: jamesgao-jpg

src/index/index.cc

@@ -156,8 +156,7 @@ Index<T>::Search(const DataSetPtr dataset, const Json& json, const BitsetView& b
         span_ptr->SetAttribute(meta::DIM, Dim());
         span_ptr->SetAttribute(meta::NQ, dataset->GetRows());
     }
-    [[maybe_unused]] auto trace_span = span_ptr != nullptr ? milvus::tracer::SetTraceSpan(op_context, span_ptr)
-                                                           : milvus::tracer::ScopedTraceSpan{};
+    auto op_context_trace_span_guard = milvus::tracer::SetTemporaryOpContextTraceSpan(op_context, span_ptr);
     // LCOV_EXCL_STOP
 
     TimeRecorder rc("Search");
@@ -249,8 +248,7 @@ Index<T>::RangeSearch(const DataSetPtr dataset, const Json& json, const BitsetVi
         span_ptr->SetAttribute(meta::DIM, Dim());
         span_ptr->SetAttribute(meta::NQ, dataset->GetRows());
     }
-    [[maybe_unused]] auto trace_span = span_ptr != nullptr ? milvus::tracer::SetTraceSpan(op_context, span_ptr)
-                                                           : milvus::tracer::ScopedTraceSpan{};
+    auto op_context_trace_span_guard = milvus::tracer::SetTemporaryOpContextTraceSpan(op_context, span_ptr);
     // LCOV_EXCL_STOP
 
     TimeRecorder rc("Range Search");