[erlang-questions] Mnesia schema replicas
Mon Feb 8 10:13:17 CET 2016
Once upon a time, change_config didn't exist and you added new nodes with
add_table_copy, I do think that is still works.
The call to the mnesia:add_table_copy(schema, slaveNode, ram_copies), must
on the server before change_config is done.
On Mon, Feb 8, 2016 at 9:59 AM Vimal Kumar <vimal7370@REDACTED> wrote:
> Hi Dan,
> On Mon, Feb 8, 2016 at 2:11 PM, Dan Gudmundsson <dgud@REDACTED> wrote:
>> When you start mnesia without calling create_schema, mnesia will create
>> an empty ram_copies schema for you.
>> change_config(extra_db_nodes, ..) will connect and merge schema with the
>> What you probably want is to call mnesia:change_table_copy_type(schema,
>> disc_copies, node)) after change_config.
> True, and that is what I normally do. However, the documentation says:
> "The functions mnesia:add_table_copy/3 and mnesia:del_table_copy/2 can be
> used to add and delete replicas of the schema table."
> Is this statement correct, or a bug in documentation? Has anyone tried to
> add replica of schema table using mnesia:add_table_copy/3 and succeeded?
>> On Sun, Feb 7, 2016 at 7:52 PM Vimal Kumar <vimal7370@REDACTED> wrote:
>>> Hello list,
>>> Ref (Section 6.6): http://erlang.org/doc/apps/mnesia/Mnesia_chap5.html
>>> The functions mnesia:add_table_copy/3 and mnesia:del_table_copy/2 can be
>>> used to add and delete replicas of the schema table. Adding a node to the
>>> list of nodes where the schema is replicated affects the following:
>>> It allows other tables to be replicated to this node.
>>> It causes Mnesia to try to contact the node at startup of disc-full
>>> -END QUOTE-
>>> I can use the functions mnesia:add_table_copy/3 and
>>> mnesia:del_table_copy/2 to add and delete replicated copies of other tables
>>> successfully, but not table 'schema'. In fact I am not sure at what point
>>> in initialization process of a new mnesia node should this be run. Please
>>> $ erl -mnesia -sname slave
>>> Erlang/OTP 18 [erts-7.0] [source] [64-bit] [smp:4:4] [async-threads:10]
>>> [hipe] [kernel-poll:false]
>>> Eshell V7.0 (abort with ^G)
>>> (slave@REDACTED)1> mnesia:start().
>>> (slave@REDACTED)3> mnesia:change_config(extra_db_nodes,
>>> (slave@REDACTED)5> mnesia:add_table_copy(schema, node(),
>>> erlang-questions mailing list
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