diff --git a/orm_lib/inc/drogon/orm/SqlBinder.h b/orm_lib/inc/drogon/orm/SqlBinder.h
index f8b9cc60..fb00a268 100644
--- a/orm_lib/inc/drogon/orm/SqlBinder.h
+++ b/orm_lib/inc/drogon/orm/SqlBinder.h
@@ -208,7 +208,7 @@ class SqlBinder
               typename traits = FunctionTraits<CallbackType>>
     typename std::enable_if<traits::isExceptCallback && traits::isPtr, self>::type &operator>>(CallbackType &&callback)
     {
-        LOG_DEBUG << "ptr callback";
+        //LOG_DEBUG << "ptr callback";
         _isExceptPtr = true;
         _exceptPtrCallback = std::forward<CallbackType>(callback);
         return *this;
@@ -258,6 +258,7 @@ class SqlBinder
         _parameters.push_back((char *)obj.get());
         _length.push_back(sizeof(T));
         _format.push_back(1);
+        //LOG_TRACE << "Bind parameter:" << parameter;
         return *this;
     }
     //template <>
diff --git a/orm_lib/src/postgresql_impl/PgClientImpl.cc b/orm_lib/src/postgresql_impl/PgClientImpl.cc
index 59ab6328..25a3e49a 100644
--- a/orm_lib/src/postgresql_impl/PgClientImpl.cc
+++ b/orm_lib/src/postgresql_impl/PgClientImpl.cc
@@ -109,7 +109,7 @@ void PgClientImpl::execSql(const DbConnectionPtr &conn,
                                   _loopPtr->queueInLoop([=]() {
                                       std::vector<const char *> paras;
                                       std::vector<int> lens;
-                                      for (auto p : cmd._parameters)
+                                      for (auto &p : cmd._parameters)
                                       {
                                           paras.push_back(p.c_str());
                                           lens.push_back(p.length());
@@ -147,8 +147,6 @@ void PgClientImpl::execSql(const std::string &sql,
         {
             if (_busyConnections.size() == 0)
             {
-                //std::cout<<"no connection"<<std::endl;
-                //FIXME call exception callback
                 try
                 {
                     throw BrokenConnection("No connection to postgreSQL server");
@@ -184,14 +182,23 @@ void PgClientImpl::execSql(const std::string &sql,
     }
     if (busy)
     {
-        //FIXME call except callback
+        try
+        {
+            throw Failure("Too many queries in buffer");
+        }
+        catch (...)
+        {
+            exceptCb(std::current_exception());
+        }
         return;
     }
+    //LOG_TRACE << "Push query to buffer";
     SqlCmd cmd;
     cmd._sql = sql;
     cmd._paraNum = paraNum;
     for (size_t i = 0; i < parameters.size(); i++)
     {
+        //LOG_TRACE << "parameters[" << i << "]=" << (size_t)(parameters[i]);
         cmd._parameters.push_back(std::string(parameters[i], length[i]));
     }
     cmd._format = format;