Patroni Postgres Cluster，'TL'在'patronictl list'的输出中是什么意思

执行。

patronictl list

生产

+ Cluster: psql-core03-uat-kong (6867488892458676291) ------+----+-----------+
|         Member         |      Host     |  Role  |  State  | TL | Lag in MB |
+------------------------+---------------+--------+---------+----+-----------+
| psql-podname-blahbla-0 |  ##.##.###.## | Leader | running | 46 |           |
| psql-podname-blahbla-1 |  ##.##.###.## |        | running | 21 |     14288 |
| psql-podname-blahbla-2 |  ##.##.###.## |        | running | 46 |         0 |
+------------------------+---------------+--------+---------+----+-----------+

有谁知道'TL'栏代表什么意思？翻遍了手册，但没有乐趣。

谢谢