item_insert_order
item_insert_order(tree, 0, order);
item_insert_order(tree, 3 << RADIX_TREE_MAP_SHIFT, 0);
item_insert_order(tree, 2 << RADIX_TREE_MAP_SHIFT, 0);
item_insert_order(tree, index, order);
err = item_insert_order(xa, index[i], order[i]);
assert(!item_insert_order(xa, index[i], order[i]));