Now when trying to understand this and get everything right, shouldn't 
"$driver = 'memcache';" be set after setting the "$persistent_params" 
array to which "$driver" is passed? When I read the code above, then 
"memcache" is passed to this array, is this intended?



Sorry if this question is stupid, but I couldn't figure out something 
else that causes my sessions not to be saved in the sql session table.

...ok thanks and sorry for the noise, I was definitely not awake :-)

Why do we need to define 'persistent_params' in conf.xml?  All this 
code is doing is saving the original params (for the persistent 
driver) so that the memcache driver can later pass these params on to 
the persistent driver.  It's just a temporary holding place to allow 
us to pass driver information between classes.  $driver is replaced 
with 'memcache' and $params is replaced with the params needed for the 
'memcache' driver, so we need a way to make sure the original values 
aren't blown away.



Nowhere are we trying to load 'persistent_params' from the conf.xml, 
and there is absolutely no reason we would ever want to.

When using e.g. the sql session handler together with memcache 
conf.xml is not setting or asking for the persistent_params used in 
SessionHandler.php.



         if ($driver == 'memcached') {

             // Trap for old driver name.

             $driver = 'memcache';

         } elseif (($driver != 'memcache') && !empty($params['memcache'])) {

             $driver = 'memcache';

             unset($params['memcache']);

             $persistent_params = array('persistent_driver' => 
$driver, 'persistent_params' => $params);

             $params = null;

         }







This causes that the sessions are actually not stored in the sql 
database and therefore the are not persisted.