BT_NOSYNC
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);
if (!F_ISSET(bt->flags, BT_NOSYNC))
db_flags |= BT_NOSYNC;
flags |= BT_NOSYNC;