[
  {
    "createIndexes": "notifications",
    "indexes": [
      { "key": { "owner_uid": 1, "created_at": -1 }, "name": "owner_notifications_recent" },
      { "key": { "owner_uid": 1, "read_at": 1 }, "name": "owner_notifications_unread" },
      { "key": { "owner_uid": 1, "kind": 1, "ref_type": 1, "ref_id": 1, "created_at": -1 }, "name": "owner_notification_ref_recent" }
    ]
  }
]