xf_session & xf_session_activity : Is it okay to have 'overhead'?


Well-known member
I'm checking out database through phpMyadmin and found out that of all the tables, xf_session, xf_session_activity & xf_session_admin are the three tables that show 'overhead's - 1 MiB, 128.3 KiB and 272 B respectively.

Is this normal? If not -

1. What causes this overhead?
2. How to fix it permanently?


Well-known member

I checked my config file and it says the following -

$config['cache']['enabled'] = true;
$config['cache']['frontend'] = 'Core';
$config['cache']['frontendOptions']['cache_id_prefix'] = 'xf_';
$config['cache']['backend'] = 'File';
$config['cache']['backend'] = 'Memcached';
$config['cache']['backendOptions'] = array(
    'compression' => false,
    'servers' => array(
            // your memcached server IP /address
            'host' => 'localhost',
            // memcached port
            'port' => 11211,


Well-known member
@Mike - I've moved from Memcache to simple file cache following the guide on the URL you provided. Yet, the xf_session table shows overhead. It's much lesser than before, but it's still there.

I'll give APC a try later tonight.

Also, the xf_session_activity seems to be a "memory" table; should I just leave it as it is - or is there anything I can do about it?


XenForo developer
Staff member
As I mentioned, if you're moving to serving sessions out of the cache, you need to truncate (or optimize) the xf_session table to save the overhead. (You're just not using it any more so all of the data is going to stay there, including the overhead.)


Well-known member
Just checked and the xf_session table overhead is now empty. Should I ignore the xf_session_activity table? It continues to show overhead.