This class provides several approaches for querying data from the database:

1. Async queries: Used under MySQLi with MySQLnd.
2. Parallel queries: Used under HPHP.
3. Multi queries: Used under MySQLi or HPHP.
4. Single queries: Used under MySQL.

The class automatically decides which approach to use. Usage is like with other futures:

$futures = array();
$futures[] = new QueryFuture($conn1, 'SELECT 1');
$futures[] = new QueryFuture($conn1, 'DELETE FROM table');
$futures[] = new QueryFuture($conn2, 'SELECT 2');

foreach (new FutureIterator($futures) as $future) {
  try {
    $result = $future->resolve();
  } catch (AphrontQueryException $ex) {
  }
}

$result contains a list of dicts for select queries or number of modified rows for modification queries.