Mnesia with Memento lost all records for all tables

[Exadra37]

@JeyHey

Maybe it was some race condition caused by trying to create a schema that already exists… who knows now???

I took a quick look on how Memento creates the schema. It checks that the path exists and then simply calls mnesia:create_schema which does never delete or overwrite an existing schema.

Thanks for the update. I had started to inspect my self the Memento code some minutes ago, but had not went that far yet

@JeyHey

Given the age and robustness of Mnesia, I would also exclude almost certainly a bug in Mnesia.

Well, Mnesia is known for a lot of quirks, but to be honest all databases have them, thus a bug cannot be put aside, or even this being an unexpected behavior, like this one:

Unexpected behaviour with mnesia - not actually durable?

I’m observing behavior with mnesia that is unexpected by me and could use some help understanding what’s going on. I’ve tested this with erlang 21.0.1 and 21.2.2, and elixir 1.7.4. Given two scripts: write.exs IO.puts "Creating schema..." :ok = :mnesia.create_schema([node()]) IO.puts "Starting mnesia..." :ok = :mnesia.start() IO.puts "Creating table..." {:atomic, :ok} = :mnesia.create_table(:example, [{:disc_only_copies, [node()]}, type: :set, attributes: [:name, :value]]) IO.puts "Setting :f…

@JeyHey

I can only guess the problem but I would say that either the environment variables changed (something you already checked though) or somewhere else in your pipeline the target directory gets deleted.

As far as I am aware nothing have changed. The app is running from a folder in my laptop that was created with:

git clone my_repo
cd my_repo
git checkout dev-branch
mix deps.get
mix phx.server

This server is only stopped when I restart my laptop(forced by the OS) or by me when doing ctrl c + c.

If, I do a git diff I can confirm that nothing have changed in the folder, and I have not done a git pull to update the branch in months.