Show error when user tries to use wrong database

Author: kelvich

multimaster.c

@@ -218,6 +218,7 @@ char const* const MtmTxnStatusMnem[] =
 bool  MtmDoReplication;
 char* MtmDatabaseName;
 char* MtmDatabaseUser;
+Oid   MtmDatabaseId;
 
 int   MtmNodes;
 int   MtmNodeId;
@@ -938,6 +939,12 @@ MtmPrePrepareTransaction(MtmCurrentTrans* x)
 	bool found;
 	MTM_TXTRACE(x, "PrePrepareTransaction Start");
 
+	if (!MtmDatabaseId)
+		MtmDatabaseId = get_database_oid(MtmDatabaseName, false);
+
+	if (MtmDatabaseId != MyDatabaseId)
+		MTM_ELOG(ERROR, "Refusing to work. Multimaster configured to work with database '%s'", MtmDatabaseName);
+
 	if (!x->isDistributed) {
 		return;
 	}