class QueryFactory

1. 8.x drupal/core/lib/Drupal/Core/Entity/Query/QueryFactory.php \Drupal\Core\Entity\Query\QueryFactory
2. 8.x drupal/core/lib/Drupal/Core/Config/Entity/Query/QueryFactory.php \Drupal\Core\Config\Entity\Query\QueryFactory
3. 8.x drupal/core/modules/field_sql_storage/lib/Drupal/field_sql_storage/Entity/QueryFactory.php \Drupal\field_sql_storage\Entity\QueryFactory

field_sql_storage.services.yml in drupal/core/modules/field_sql_storage/field_sql_storage.services.yml

drupal/core/modules/field_sql_storage/field_sql_storage.services.yml

entity.query.field_sql_storage in drupal/core/modules/field_sql_storage/field_sql_storage.services.yml

Drupal\field_sql_storage\Entity\QueryFactory

class QueryFactory {

  /**
   * Constructs a QueryFactory object.
   *
   * @param \Drupal\Core\Database\Connection $connection
   *   The database connection used by the entity query.
   */
  function __construct(Connection $connection) {
    $this->connection = $connection;
  }

  /**
   * Constructs a entity query for a certain entity type.
   *
   * @param string $entity_type
   *   The entity type.
   * @param string $conjunction
   *   - AND: all of the conditions on the query need to match.
   *   - OR: at least one of the conditions on the query need to match.
   *
   * @return \Drupal\field_sql_storage\Entity\Query
   *   The factored query.
   */
  function get($entity_type, $conjunction, EntityManager $entity_manager) {
    return new Query($entity_type, $entity_manager, $conjunction, $this->connection);
  }

  /**
   * Constructs a entity aggregation query for a certain entity type.
   *
   * @param string $entity_type
   *   The entity type.
   * @param string $conjunction
   *   - AND: all of the conditions on the query need to match.
   *   - OR: at least one of the conditions on the query need to match.
   *
   * @return \Drupal\field_sql_storage\Entity\QueryAggregate
   *   The factored aggregation query.
   */
  function getAggregate($entity_type, $conjunction, EntityManager $entity_manager) {
    return new QueryAggregate($entity_type, $entity_manager, $conjunction, $this->connection);
  }

}