gistfile1.perl

UPDATE node_items
SET payload = $5
FROM nodes
JOIN users ON (users.user_id = nodes.node_id)
JOIN hosts ON (hosts.host_id = users.host_id)
WHERE 
    hosts.name = $1 AND
    users.id = $2 AND
    nodes.name = $3 AND
    node_items.node_id = nodes.id AND
    node_items.user_id = users.id;