How to tell variable_get to get the value from the database and not the $conf array? variable_get seems to always used $conf array which is fetched a single time.  In a long running process where the value of a variable may have changed during operations this causes problems.  Is there a simple mechanism in Drupal to tell variable_get to refetch the array from the database rather than using the in-memory variable?
I don't think Drupal core has anything like that, no. For speed and efficiency, the variables array is in memory pretty much as soon as settings.php has been processed.

You've always got db_query():

$var = db_query('SELECT value FROM {variable} WHERE name = :name', array(':name' =&gt; 'var_name'))-&gt;fetchField();
$var = unserialize($var);


It would be trivial to build up an efficient variable_get_from_db function based on that.