Migrations: Create index after filling up the db.

priv/repo/migrations/20191007123056_add_ap_id_column_to_objects.exs

@@ -5,7 +5,5 @@ defmodule Pleroma.Repo.Migrations.AddApIdColumnToObjects do
     alter table(:objects) do
       add :ap_id, :string
     end
-
-    create unique_index(:objects, [:ap_id])
   end
 end

priv/repo/migrations/20191007160755_fill_object_ap_id_field.exs

@@ -3,5 +3,6 @@ defmodule Pleroma.Repo.Migrations.FillObjectApIdField do
 
   def change do
     execute("update objects set ap_id = data->>'id'")
+    create unique_index(:objects, [:ap_id])
   end
 end