repo: add migration to fill recipient_users column

priv/repo/migrations/20190825233255_fill_recipient_users_in_activities.exs

@@ -0,0 +1,31 @@
+defmodule Pleroma.Repo.Migrations.FillRecipientUsersInActivities do
+  use Ecto.Migration
+
+  alias Pleroma.RepoStreamer
+  alias Pleroma.User
+
+  import Ecto.Query
+
+  def up do
+    # copy users without as:Public
+    execute("""
+    update activities set recipient_users = array_remove(recipients, 'https://www.w3.org/ns/activitystreams#Public');
+    """)
+
+    # strip followers collections
+    from(
+      u in User,
+      where: not(is_nil(u.follower_address))
+    )
+    |> RepoStreamer.chunk_stream(512)
+    |> Stream.each(fn chunk ->
+      chunk
+      |> Enum.each(fn %User{} = u ->
+        execute("update activities set recipient_users = array_remove(recipient_users, '#{u.follower_address}') where recipient_users && array['#{u.follower_address}'::varchar]")
+      end)
+    end)
+    |> Stream.run()
+  end
+
+  def down, do: :ok
+end