Mnesia -- multiple schemas?

Dan Gudmundsson <>
Fri Feb 22 09:20:14 CET 2002

Chris Pressey writes:
 > What I would really like would be if Mnesia could add or remove nodes from
 > its schema after the schema has been created (perhaps I am living in a
 > fantasy world though.)  All nodes must be up and have mnesia stopped while
 > creating or destroying a schema (but they must have mnesia started when
 > creating tables.)  This is a bit tiresome to manually set up on a large
 > number of nodes, and pretty much rules out ad hoc deployment.  If anyone
 > knows a nifty trick to make this more painless, I'm all ears  :)

To add a node 
On one of existing nodes
mnesia:add_table_copy(schema, Node, ram_copies),
mnesia:change_table_copy(schema, Node, disc_copies).

Or on the new node 
or mnesia:change_config(extra_db_nodes, [Nodes]),
mnesia:change_table_copy(schema, node(), disc_copies).

Delete the replica of every table on that node
and then delete the schema.
mnesia:del_table_copy(schema, Node)


Dan Gudmundsson               Project:    Mnesia, Erlang/OTP
Ericsson Utvecklings AB       Phone:      +46  8 727 5762 
UAB/F/P                       Mobile:     +46 70 519 9469
S-125 25 Stockholm            Visit addr: Armborstv 1 

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