Changes between Version 2 and Version 3 of NifDB

Timestamp:

Apr 17, 2012, 10:03:40 AM (14 years ago)

Author:

manualwiki

Comment:

added some more example to NifDB

NifDB

@@ -34 +34 @@
 }}}
 
+After the system started, you can use is it like with the MNESIA database backend,
+but with the NIF graph backend there are some extra functions.
+(For further informations see: [[ErlangShellInterface|ri]])
+
+= Backup-system example =
+
 After the system is started, the following operations work on the full database.
 
@@ -66 +72 @@
 ri:ls_backups().
 
-% Undo all changes made since the last backup.
+% Undo all changes made since the last backup. So it will load backup.2.
 ri:undo().
+
+% You can restore a certain backup.
+% Here you can specify the backup as in ri:backup_info/1.
+ri:restore(1).
 
 % Removes all backups.
@@ -73 +83 @@
 }}}
 
-You can also use all [[SemanticQuery|querying]] and [[RefactoringSteps|refactoring functionalities]].
+= Graph operations example =
+With the NIF database, you may have more graphs.
+The graphs does not affect each other, so every graph has its own database, and
+backups, etc. After restarting the tool, the last used graph will be loaded.
+Let's see an example:
+
+{{{
+% By default a refactorerl_0 named graph created.
+% So after the first startup, the ri:actual_graph/0
+% operation should print refactorerl_0. 
+ri:actual_graph().
+refactorerl_0
+
+% Now create a graph. The name of the graph must be an atom.
+ri:create_graph(graph_name).
+
+% You can list the created graphs.
+ri:ls_graphs().
+[graph_name, refactorerl_0]
+
+% Load the previously created graph.
+ri:load_graph(graph_name).
+ok
+ri:actual_graph().
+graph_name
+
+% You may want rename the refactorerl_0 graph to someting else.
+% You can even rename the actual graph.
+ri:rename_graph(refactorerl_0, some_other_name).
+ok
+ri:ls_graphs().
+[graph_name, some_other_name]
+
+% Now delete the graph which is not loaded.
+% Of course, you cannot delete the actual graph.
+% Warning: It deletes the whole graph from the disk,
+% so it cannot be recovered later.
+ri:delete_graph(some_other_name).
+
+% Or you can just delete all graphs.
+% After the deletion, it creates the default refactorerl_0 graph.
+ri:delete_all_graphs().
+ok
+ri:ls_graphs().
+refactorerl_0
+
+}}}
+
+If something happened to database, then after startup you will get a message about it
+and a new default graph will be created. If refactorerl_0 exists, then refactorerl_1 will
+be created, and so on. The corrupted database will not be deleted by the system.
+If the user wants to load a corrupted backup, then the system will print an error message,
+and the backup will have a 'corrutped_' prefix (so the system renames it), and the graph
+will remain the same.
 
 = Comparison with the Mnesia back-end =