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--- a/src/rcldb/rcldb.h
+++ b/src/rcldb/rcldb.h
@@ -95,7 +95,8 @@
     ~Db();
 
     enum OpenMode {DbRO, DbUpd, DbTrunc};
-    bool open(OpenMode mode);
+    enum OpenError {DbOpenNoError, DbOpenMainDb, DbOpenExtraDb};
+    bool open(OpenMode mode, OpenError *error = 0);
     bool close();
     bool isopen();