Add controldb_name GUC

src/backend/distributed/shared_library_init.c

@@ -1023,6 +1023,16 @@ RegisterCitusConfigVariables(void)
 		GUC_STANDARD,
 		NULL, NULL, NULL);
 
+	DefineCustomStringVariable(
+		"citus.controldb_name",
+		gettext_noop("Which database is designated as the controldb"),
+		NULL,
+		&ControlDbName,
+		"",
+		PGC_SU_BACKEND,
+		GUC_STANDARD,
+		NULL, NULL, NULL);
+
 	DefineCustomEnumVariable(
 		"citus.coordinator_aggregation_strategy",
 		gettext_noop("Sets the strategy for when an aggregate cannot be pushed down. "

src/backend/distributed/utils/maintenanced.c

@@ -99,6 +99,7 @@ int Recover2PCInterval = 60000;
 int DeferShardDeleteInterval = 15000;
 int BackgroundTaskQueueCheckInterval = 5000;
 int MaxBackgroundTaskExecutors = 4;
+char *ControlDbName = "";
 
 /* config variables for metadata sync timeout */
 int MetadataSyncInterval = 60000;
@@ -146,6 +147,12 @@ InitializeMaintenanceDaemon(void)
 void
 InitializeMaintenanceDaemonForAdminDB(void)
 {
+	if (strcmp(ControlDbName, "") == 0)
+	{
+		elog(LOG, "There is no designated control database.");
+		return;
+	}
+
 	BackgroundWorker worker;
 
 	memset(&worker, 0, sizeof(worker));
@@ -335,7 +342,7 @@ CitusMaintenanceDaemonMain(Datum main_arg)
 	if (databaseOid == 0)
 	{
 		/* TODO : Get the admin database name from GUC contro_db*/
-		char *databaseName = "postgres";
+		char *databaseName = ControlDbName;
 
 		BackgroundWorkerInitializeConnection(databaseName, NULL, 0);
 

src/include/distributed/maintenanced.h

@@ -20,6 +20,7 @@
 
 /* config variable for */
 extern double DistributedDeadlockDetectionTimeoutFactor;
+extern char *ControlDbName;
 
 extern void StopMaintenanceDaemon(Oid databaseId);
 extern void TriggerNodeMetadataSync(Oid databaseId);