boolean prune(final Key key) throws PersistitException {
        Buffer buffer = null;
        Debug.$assert1.t(_tree.isValid());
        try {
            search(key, true);
            buffer = _levelCache[0]._buffer;
            if (buffer != null) {
                return buffer.pruneMvvValues(_tree, true);
            } else {
                return false;
            }
        } finally {
            if (buffer != null) {
                buffer.release();
            }
        }
    }