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?
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:
rpc:call(nodeA@ip1, mnesia, read, ....).
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.