mysqli-rw split driver.

Added a new MySQLI-RW driver
Make sure you have two db-groups called "rw_write" and "rw_read"

file: database.php
$db['rw_write']...
$db['rw_read]...

Use as you would normaly $db->query(...)
To force a read from write/master  use $db->query_from_master(...) instead.