public function createMigrationCollection()
    {
        $this->validate();

        if (true !== $this->migrationCollectionCreated) {
            $collection = $this->getCollection();
            $collection->ensureIndex(['v' => -1], ['name' => 'version', 'unique' => true]);
            $this->migrationCollectionCreated = true;
        }

        return true;
    }