[erlang-questions] mnesia fallbacks with local_content

Håkan Mattsson <>
Thu Jan 9 13:51:47 CET 2014


It is a bit complicated and partly undocumented. You need to do it in
several steps:

1. Activate a global checkpoint (mnesia:activate_checkpoint/1).
2. Perform a local backup on each node (mnesia:backup_checkpoint/3)
3. Dectivate the checkpoint (mnesia:deactivate_checkpoint/1)
4. Install a local fallback (from the local backup) on each node
(mnesia:install_fallback/2)

See mnesia_log:check_backup_arg_type/2 for details of the third
(partly undocumented) argument of mnesia:backup_checkpoint/3.

/Håkan

On Wed, Jan 8, 2014 at 7:48 PM, Anders Nygren <> wrote:
> I am trying to figure out if it is possible to use mnesia fallbacks with
> tables with local_content. The documentation does not provide much
> information on this and my experiments seems to imply that it is not
> possible.
>
> Running erlang 5.9.1, mnesia 4.7, I have two nodes A and B.
>
> I have a table t1, that has {local_content, true},
> If I take a backup on node A and install that as a fallback and then restart
> mnesia, the content of table t1 on node B gets replaced with the contents
> from t1 on node A.
>
> Is there any way to get this to work, i.e. to get the local contents
> restored correctly on all nodes from a fallback?
>
> /Anders
>
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