Another nice new function that comes with mysqlnd: return all rows of

Another nice new function that comes with mysqlnd: return all rows of
a result set in one array. This is handy if want to fetch all results and
pass the data directly to a template engine, for example. In this case
you save a loop.

1) Currently:
  $all_rows = array();
  while ($row = mysqli_fetch_assoc($res))
   $all_rows[] = $row;

2) With mysqli_fetch_all:
  $all_rows = mysqli_fetch_all($res, MYSQL_ASSOC)

Note: if you need the loop for processing each row, try variant 1) for
performance reasons.