Add queued timestamp.
function aggregator_update_7002() {
db_add_field('aggregator_feed', 'queued', array(
'type' => 'int',
'not null' => TRUE,
'default' => 0,
'description' => 'Time when this feed was queued for refresh, 0 if not queued.',
));
db_add_index('aggregator_feed', 'queued', array(
'queued',
));
}