Hi Nima,
We have a scheduled procedure every 5 minutes on the slaves,
Here is the code:
set root_node_id [db_string get_root_node_id {select node_id from site_nodes where parent_id is null} -default {}]
if { ![empty_string_p $root_node_id] } {
site_node::update_cache -sync_children -node_id $root_node_id
}