diff --git a/src/core/config/CMakeLists.txt b/src/core/config/CMakeLists.txt
index dc30d259..a2b181b6 100644
--- a/src/core/config/CMakeLists.txt
+++ b/src/core/config/CMakeLists.txt
@@ -25,7 +25,7 @@ OPTION(CONFIG_FAST_BREAKPOINTS          "Enable fast breakpoints (requires break
 OPTION(CONFIG_FAST_WATCHPOINTS          "Enable fast watchpoints (requires memory access events to be enabled)" OFF)
 SET(SERVER_COMM_HOSTNAME        "localhost"  CACHE STRING "Job-server hostname or IP")
 SET(SERVER_COMM_TCP_PORT        "1111"       CACHE STRING "Job-server TCP port")
-SET(SERVER_OUT_QUEUE_SIZE       "10000"      CACHE STRING "Queue size for outbound jobs (0 = unlimited)")
+SET(SERVER_OUT_QUEUE_SIZE       "0"      CACHE STRING "Queue size for outbound jobs (0 = unlimited)")
 SET(SERVER_PERF_LOG_PATH        "perf.log"   CACHE STRING "A file name for storing the server's performance log (CSV)")
 SET(SERVER_PERF_STEPPING_SEC    "1"          CACHE STRING "Stepping of performance measurements in seconds")
 SET(CLIENT_RAND_BACKOFF_TSTART  "3"          CACHE STRING "Lower limit of client's backoff phase in seconds")
diff --git a/src/core/cpn/DatabaseCampaign.cc b/src/core/cpn/DatabaseCampaign.cc
index b9832275..5e32d81d 100644
--- a/src/core/cpn/DatabaseCampaign.cc
+++ b/src/core/cpn/DatabaseCampaign.cc
@@ -200,6 +200,16 @@ bool DatabaseCampaign::run_variant(Database::Variant variant) {
 			log_send << "pushed " << sent_pilots << " pilots into the queue" << std::endl;
 		}
 	}
+
+	if (*mysql_error(db->getHandle())) {
+		log_send << "MYSQL ERROR: " << mysql_error(db->getHandle()) << std::endl;
+		return false;
+	}
+
+	assert(experiment_count == sent_pilots && "ERROR: not all unfinished experiments pushed to queue");
+
+	mysql_free_result(pilots);
+
 	return true;
 
 }