# UPGRADE FROM 2.1 to 2.2 ## Aggregation The new `Doctrine\ODM\MongoDB\Aggregation\Builder::getAggregation()` method returns an `Doctrine\ODM\MongoDB\Aggregation\Aggregation` instance, comparable to the `Query` class. The `Doctrine\ODM\MongoDB\Aggregation\Builder::execute()` method was deprecated and will be removed in ODM 3.0. The `Doctrine\ODM\MongoDB\Aggregation\Stage\Match` and `Doctrine\ODM\MongoDB\Aggregation\Stage\GraphLookup\Match` classes were deprecated and replaced by `Doctrine\ODM\MongoDB\Aggregation\Stage\MatchStage` and `Doctrine\ODM\MongoDB\Aggregation\Stage\GraphLookup\MatchStage` respectively. This change was necessary due to `match` being a reserved keyword in PHP 8. You must replace any usage of this class before you migrate to PHP 8. ## Document indexes (annotations) Using `@Index` annotation(s) on a class level is a preferred way for defining indexes for documents. Using `@Index` in the `@Indexes` annotation or an `indexes` property of other annotations was deprecated and will be removed in ODM 3.0.