Aggregate throws error when execute returns more than 1000 events.

[thomasdziedzic]

I have the following pseudo code:

defmodule Aggregate
  def execute(_state, cmd) do
    cmd.lots_of_events
    |> Enum.take(1000)
  end
end

Which works as expected, but when I try taking 1001:

defmodule Aggregate
  def execute(_state, cmd) do
    cmd.lots_of_events
    |> Enum.take(1001)
  end
end

I get an error:

[debug] Appended 1000 event(s) to stream "0"
[warning] Failed to append events to stream "0" due to: :duplicate_stream_uuid
[debug] Appended 1000 event(s) to stream "0"
[warning] Failed to append events to stream "0" due to: :duplicate_stream_uuid
** (MatchError) no match of right hand side value: {:error, :already_retried_once}

This is on a brand new database (reproduced it right after running mix do ecto.drop, ecto.create, ecto.migrate, event_store.create, event_store.init)