migrate/database/mongodb/examples/migrations/002_create_indexes.up.json

[{
  "createIndexes": "mycollection",
  "indexes": [
    {
      "key": {
        "username": 1,
        "created": -1
      },
      "name": "username_sort_by_asc_created",
      "background": true
    },
    {
      "key": {
        "email": 1
      },
      "name": "unique_email",
      "unique": true,
      "background": true
    }
  ]
}]