mnesia:start()启动数据库 - Erlang中文论坛

%% 前面调用了mnesia:start().
add_extra_nodes([Node | Tail]) ->
case mnesia:change_config(extra_db_nodes, [Node]) of
{ok, [Node]} ->
{atomic, ok} = mnesia:add_table_copy(schema, node(), ram_copies),%% 这里报错了

         Tables = mnesia:system_info(tables),
         mnesia:wait_for_tables(Tables, ?WAIT_FOR_TABLES);
      _ ->
         add_extra_nodes(Tail)
end.

Rs = mnesia:add_table_copy(schema, node(), ram_copies),

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(test@localhost)1> mnesia:start().
ok
(test@localhost)2> mnesia:change_config(extra_db_nodes, ['contact1@localhost']).
{ok,[contact1@localhost]}
(test@localhost)3> mnesia:add_table_copy(schema, node(), ram_copies).
{aborted,{already_exists,schema,test@localhost}}
(test@localhost)4> mnesia:system_info().
===> System info in version "4.14.3", debug level = none <===
opt_disc. Directory "/data/opensource/my_try/Mnesia.test@localhost" is NOT used.
use fallback at restart = false
running db nodes = [contact1@localhost,contact2@localhost,test@localhost]
stopped db nodes = []
master node tables = []
remote = []
ram_copies = [schema]
disc_copies = []
disc_only_copies = []
[{contact1@localhost,ram_copies},
{contact2@localhost,ram_copies},
{test@localhost,ram_copies}] = [schema]
4 transactions committed, 1 aborted, 0 restarted, 0 logged to disc
0 held locks, 0 in queue; 0 local transactions, 0 remote
0 transactions waits for other nodes: []

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