Add FK to repositories_changed_event_id column on geo_event_log table

db/migrate/20170801201439_add_geo_repositories_changed_events_foreign_key.rb

+class AddGeoRepositoriesChangedEventsForeignKey < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  disable_ddl_transaction!
+
+  def up
+    add_concurrent_foreign_key :geo_event_log, :geo_repositories_changed_events,
+                               column: :repositories_changed_event_id, on_delete: :cascade
+  end
+
+  def down
+    remove_foreign_key :geo_event_log, column: :repositories_changed_event_id
+  end
+end

db/schema.rb

@@ -1988,6 +1988,7 @@ ActiveRecord::Schema.define(version: 20170803130232) do
   add_foreign_key "environments", "projects", name: "fk_d1c8c1da6a", on_delete: :cascade
   add_foreign_key "events", "projects", name: "fk_0434b48643", on_delete: :cascade
   add_foreign_key "forked_project_links", "projects", column: "forked_to_project_id", name: "fk_434510edb0", on_delete: :cascade
+  add_foreign_key "geo_event_log", "geo_repositories_changed_events", column: "repositories_changed_event_id", name: "fk_4a99ebfd60", on_delete: :cascade
   add_foreign_key "geo_event_log", "geo_repository_deleted_events", column: "repository_deleted_event_id", name: "fk_c4b1c1f66e", on_delete: :cascade
   add_foreign_key "geo_event_log", "geo_repository_renamed_events", column: "repository_renamed_event_id", name: "fk_86c84214ec", on_delete: :cascade
   add_foreign_key "geo_event_log", "geo_repository_updated_events", column: "repository_updated_event_id", on_delete: :cascade