### Question:
RMap extends RCollection { public void deleteFast(String key) throws KitDBException { checkTxStart(); try (CloseLock ignored = checkClose()) { LockEntity lockEntity = lock(key); try { byte[] key_b = getKey(key); Meta metaV = getMeta(key_b); if (metaV == null) { checkTxCommit(); return; } deleteFast(key_b, metaV); } finally { unlock(lockEntity); } checkTxCommit(); } catch (KitDBException e) { checkTxRollBack(); throw e; } } protected  RMap(DB db); void put(String key, String mkey, byte[] value); void putTTL(String key, String mkey, byte[] value, int ttl); void put(String key, Map<String, byte[]> map); void putMayTTL(String key, int ttl, Map<String, byte[]> map); void putMayTTL(String key, int ttl, String mkey, byte[] value); Map<String, byte[]> get(String key, String... keys); byte[] get(String key, String mkey); void remove(String key, String... keys); @Override void delete(String key); @Override KeyIterator getKeyIterator(); void deleteFast(String key); @Override RIterator<RMap> iterator(String key); @Override Entry getEntry(RocksIterator iterator); @Override int getTtl(String key); @Override void delTtl(String key); @Override void ttl(String key, int ttl); @Override boolean isExist(String key); @Override int size(String key); static byte[] HEAD_B; final static byte[] HEAD_KEY_B; }### Answer:
@Test public void deleteFast() throws KitDBException { String head = "deleteFast1"; RMap map = db.getMap(); int num = 1000; for (int i = 0; i < num; i++) { map.put(head, "hello" + i, ("world" + i).getBytes()); } map.deleteFast(head); }