Mnesia：以{local_content，true}模式读取远程节点数据
有没有办法使用 mnesia 进行本地写入和全局读取（没有复制）。例如：节点 A 写入其本地 DB，节点 B 从节点 A 的 DB 读取。 除了本地存储的模式信息之外，节点 B 没有自己的任何数据。
根据文档， {local_content, true} 似乎是我需要使用的，但我一直未能成功尝试让节点 B 读取节点 A 的数据。
我的架构和表配置如下所示：
在nodeA@ip1上：
net_adm:ping('nodeB@ip2').
rd(user, {name, nick}).
mnesia:create_schema([node()|nodes()]).
mnesia:start().
mnesia:create_table(user, [ {local_content, true},
{disc_copies, [node()]},
{attributes,record_info(fields, user) }]).
%% insert data and list rows on nodeA
%% WORKS
在nodeB@ip2上：
mnesia:start().
%% code to list rows from user table on nodeA
%% throws an ERROR saying table does not exist.
配置是否错误或者可以通过其他方式完成吗？
Is there a way to do local writes and and global reads ( without replication ) using mnesia. Eg: node A writes to its local DB and node B reads from node A's DB.
Node B does not have any data of its own, apart from the schema information stored locally.
According to the documentation, {local_content, true} seems like what I need to use, but I have been unsuccessful trying to get node B to read node A's data.
My schema and table configuration look like this:
On nodeA@ip1:
net_adm:ping('nodeB@ip2').
rd(user, {name, nick}).
mnesia:create_schema([node()|nodes()]).
mnesia:start().
mnesia:create_table(user, [ {local_content, true},
{disc_copies, [node()]},
{attributes,record_info(fields, user) }]).
%% insert data and list rows on nodeA
%% WORKS
On nodeB@ip2:
mnesia:start().
%% code to list rows from user table on nodeA
%% throws an ERROR saying table does not exist.
Is the configuration wrong or can this be done in any other way?
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我认为你不能按照你提到的方式做到这一点。另一种方法可能是对节点 A 进行 rpc 调用并以这种方式获取数据。使用 mnesia 从节点 B 进行读取是没有意义的，因为无论如何它本质上只是执行 RPC。
所以节点 B 应该是：
希望这是你[某种程度上]需要的。
编辑：
哦，我忘了提一下，您不需要两个节点上的架构才能正常工作。这是假设节点 B 并不真正关心与节点 A 共享任何其他数据，它只是读取这些数据；换句话说，只需将所有 mnesia 内容保留在节点 A 上，并从节点 B 进行 RPC 调用即可。
I don't think you can do it the way you mention. Another way of doing it would probably be to make an rpc call to node A and get the data that way. There is no point in using mnesia to do the read from node B because it will essentially just do an RPC anyway.
So node B should be:
Hope this is what you [somewhat] needs.
EDIT:
Oh and I forgot to mention that you don't need the schema on both nodes for this to work. This is assuming that Node B doesn't really care about sharing any other data with Node A it just reads it; In other words just keep all the mnesia stuff on Node A and just do RPC calls from Node B.
您可能需要将节点 B 添加到架构的 extra_db_nodes 配置中。如果它是基于光盘的数据库，则不必这样做，但在 RAM 中，必须使其执行您想要的操作。
不确定具体细节，我可能会混淆把东西放在哪里。我对记忆症不太有经验，但文档表明你应该这样做。
You may need to add node B to the schema's extra_db_nodes config thingy. You shouldn't have to do that if it's a disc based db, but in RAM it's mandatory to make it do what you want.
Not sure about the specifics, i may be confusing where to put stuff. I'm not too experienced with mnesia, but the docs indicate that you should do this.