Load all nodes by type
$nids = db_select('node', 'n')
->fields('n', array('nid'))
->condition('n.type', 'NODE_TYPE')
->execute()->fetchCol();
$nodes = node_load_multiple($nids);
$nids = db_select('node', 'n')
->fields('n', array('nid'))
->condition('n.type', 'NODE_TYPE')
->execute()->fetchCol();
$nodes = node_load_multiple($nids);