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I am writing data to Mnesia from one erlang VM, now I started another erlang VM on same machine, can second VM read the data written to mnesia by first VM.

nitinjain110588
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  • Possible duplicate of [How to add a node to an mnesia cluster?](https://stackoverflow.com/questions/787755/how-to-add-a-node-to-an-mnesia-cluster) – Dániel Szoboszlay Jan 17 '19 at 23:06

2 Answers2

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To share Mnesia tables the nodes must be part of the same distributed Erlang system.

The schema defines which nodes contain the data base, cf. http://erlang.org/doc/apps/mnesia/Mnesia_chap3.html#define-a-schema

Mnesia database replication is described here: http://erlang.org/doc/apps/mnesia/Mnesia_chap5.html#distribution-and-fault-tolerance.

You can use mnesia:set_master_nodes() to define where to find a table.

Xypron
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Ofcourse you can, here is some basic way to do it:

  1. Start the two nodes - iex --name nodeA@127.0.0.1 and iex --name nodeB@127.0.0.1
  2. From the terminal of node A - Node.connect :"nodeB@127.0.0.1"
  3. From the terminal of node A - :mnesia.create_schema [node(), :"nodeB@127.0.0.1"]
  4. For node A and node B - :mnesia.start
  5. From the terminal of node A - create_table(Person, [attributes: [:id, :name]])
  6. From the terminal of node B - :mnesia.dirty_write({Person, 1, "John"})
  7. Now you can get the information that node B has written from node A through doing basic selection - :mnesia.dirty_read({Person, 1})

References: https://elixirschool.com/en/lessons/specifics/mnesia/# http://erlang.org/doc/apps/mnesia/

Tano
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