repmgr出现双主，并且时间线分叉，删除了最新的时间线节点

 遇到的问题如下：

2023-08-17 20:24:21.566 CST [1556001] LOG:  database system was interrupted; last known up at 2023-08-17 20:21:41 CST
2023-08-17 20:24:21.770 CST [1556001] LOG:  restored log file "00000009.history" from archive
cp: 无法获取'/home/postgres/pgarch/0000000A.history' 的文件状态(stat): 没有那个文件或目录
2023-08-17 20:24:21.771 CST [1556001] LOG:  entering standby mode
2023-08-17 20:24:21.772 CST [1556001] LOG:  restored log file "00000009.history" from archive
cp: 无法获取'/home/postgres/pgarch/000000090000010200000066' 的文件状态(stat): 没有那个文件或目录
2023-08-17 20:24:21.784 CST [1556001] LOG:  restored log file "000000080000010200000066" from archive
2023-08-17 20:24:21.851 CST [1556001] FATAL:  requested timeline 9 is not a child of this server's history
2023-08-17 20:24:21.851 CST [1556001] DETAIL:  Latest checkpoint is at 102/66000060 on timeline 8, but in the history of the requested timeline, the server forked off from that timeline at 102/580000A0.
2023-08-17 20:24:21.851 CST [1555991] LOG:  startup process (PID 1556001) exited with exit code 1
2023-08-17 20:24:21.851 CST [1555991] LOG:  aborting startup due to startup process failure
2023-08-17 20:24:21.851 CST [1555991] LOG:  database system is shut down
 

出现上面的原因是repmgr出现了双主。

在db206的主机上修改了shared_preload_libraries = 'pg_stat_statements'，试图重启，发现无法启动（没有提前创建pg_stat_statements扩展）导致。

[postgres@db206 data]$ vi postgresql.conf
[postgres@db206 data]$ pg_ctl restart
waiting for server to shut down...... done
server stopped
waiting for server to start....2023-08-17 18:11:53.086 CST [6497] FATAL:  could not access file "pg_stat_statements": 没有那个文件或目录
2023-08-17 18:11:53.086 CST [6497] LOG:  database system is shut down
 stopped waiting
pg_ctl: could not start server

这个时候 vi postgresql.conf 把shared_preload_libraries = 'pg_stat_statements'去掉，再次启动数据库，可以启动，试图创建，这个时候备机已经接管主机了

这个时候想起来先去修改db223的shared_preload_libraries = 'pg_stat_statements'（先在备机上给加上）

[postgres@db223 ~]$ vi pg14/data/postgresql.conf

这个时候发现出现了双主（暂时还不知道为什么会出现双主），这个时候时间线也不一样，新主是9，旧主是8

[postgres@db206 data]$  repmgr -f ~/repmgr/repmgr.conf  cluster show
 ID | Name  | Role    | Status               | Upstream | Location | Priority | Timeline | Connection string
----+-------+---------+----------------------+----------+----------+----------+----------+------------------------------------------------------------------------