btree_open
data_db = btree_open(path, BT_NOSYNC | BT_REVERSEKEY, 0644);
indx_db = btree_open(path, BT_NOSYNC, 0644);
bt = btree_open(path, BT_NOSYNC | BT_REVERSEKEY, 0644);
bt = btree_open(filename, flags | BT_NOSYNC, 0644);
struct btree *btree_open(const char *path, unsigned int flags,
ns->data_db = btree_open(ns->data_path, db_flags | BT_REVERSEKEY, 0644);
ns->indx_db = btree_open(ns->indx_path, db_flags, 0644);