class Query

class Query extends QueryBase {
    
    /**
     * The key value factory.
     *
     * @var \Drupal\Core\KeyValueStore\KeyValueFactoryInterface
     */
    protected $keyValueFactory;
    
    /**
     * Constructs a new Query.
     *
     * @param \Drupal\Core\Entity\EntityTypeInterface $entity_type
     *   The entity type.
     * @param string $conjunction
     *   - AND: all of the conditions on the query need to match.
     *   - OR: at least one of the conditions on the query need to match.
     * @param array $namespaces
     *   List of potential namespaces of the classes belonging to this query.
     * @param \Drupal\Core\KeyValueStore\KeyValueFactoryInterface $key_value_factory
     *   The key value factory.
     */
    public function __construct(EntityTypeInterface $entity_type, $conjunction, array $namespaces, KeyValueFactoryInterface $key_value_factory) {
        parent::__construct($entity_type, $conjunction, $namespaces);
        $this->keyValueFactory = $key_value_factory;
    }
    
    /**
     * {@inheritdoc}
     */
    public function execute() {
        // Load the relevant records.
        $records = $this->keyValueFactory
            ->get('entity_storage__' . $this->entityTypeId)
            ->getAll();
        // Apply conditions.
        $result = $this->condition
            ->compile($records);
        // Apply sort settings.
        foreach ($this->sort as $sort) {
            $direction = $sort['direction'] == 'ASC' ? -1 : 1;
            $field = $sort['field'];
            uasort($result, function ($a, $b) use ($field, $direction) {
                return $a[$field] <= $b[$field] ? $direction : -$direction;
            });
        }
        // Let the pager do its work.
        $this->initializePager();
        if ($this->range) {
            $result = array_slice($result, $this->range['start'], $this->range['length'], TRUE);
        }
        if ($this->count) {
            return count($result);
        }
        // Create the expected structure of entity_id => entity_id.
        $entity_ids = array_keys($result);
        return array_combine($entity_ids, $entity_ids);
    }

}