How to add mnesia node to existing cluster

Question

I have mnesia installed on a node a. I have already defined a schema and a table. Now i do not know how can i add another node b so that mnesia now can run distributed.

By distributed i mean :

• issue a insert of a record in mnesia from node a
• be able to fetch the record when querying mnesia of node b

What i have tried:

• Start node a and start mnesia
• create_schema and create_table on node a
• dirty_insert in node a

Then

• Start node b

• connect node b to node a

• from node a issue : mnesia:change_config(extra_db_nodes,[nodes()]). // doesnt matter if i issue this command from node a or node b i get the following error :

  (a@DESKTOP-GOMS8S8)7> mnesia:change_config(extra_db_nodes,[nodes()]). =ERROR REPORT==== 3-Jul-2021::13:33:16.147000 === Error in process <0.138.0> on node 'a@DESKTOP-GOMS8S8' with exit value: {function_clause, [{gen_server,do_abcast, [[['b@DESKTOP-GOMS8S8']], mnesia_controller, {'$gen_cast',{merging_schema,'a@DESKTOP-GOMS8S8'}}], [{file,"gen_server.erl"},{line,263}]}, {mnesia_controller,connect_nodes2,3, [{file,"mnesia_controller.erl"},{line,486}]}]}

  ** exception exit: function_clause in function gen_server:do_abcast/3 called as gen_server:do_abcast([['b@DESKTOP-GOMS8S8']], mnesia_controller, {'$gen_cast', {merging_schema,'a@DESKTOP-GOMS8S8'}})
  in call from mnesia_controller:connect_nodes2/3 (mnesia_controller.erl, line 486)

I just want any operation i do upon mnesia of a given node to be reflected on the others

Answer 1

nodes() already returns a list, so there is no need to wrap the return value in a list. Try this:

mnesia:change_config(extra_db_nodes,nodes()).