PostgreSQL延迟备库

[postgres@rhel6lhr data]$ cat recovery.conf |grep recovery_min
recovery_min_apply_delay = 2min
[postgres@rhel6lhr data]$ pg_ctl restart
waiting for server to shut down........ done
server stopped
waiting for server to start....2020-10-26 23:37:15.975 CST [27436] LOG:  listening on IPv4 address "0.0.0.0", port 5432
2020-10-26 23:37:15.975 CST [27436] LOG:  listening on IPv6 address "::", port 5432
2020-10-26 23:37:15.977 CST [27436] LOG:  listening on Unix socket "/tmp/.s.PGSQL.5432"
2020-10-26 23:37:15.988 CST [27436] LOG:  redirecting log output to logging collector process
2020-10-26 23:37:15.988 CST [27436] HINT:  Future log output will appear in directory "log".
 done
server started
--主库切换wal日志
postgres=# select pg_switch_wal();
-[ RECORD 1 ]-+-----------
pg_switch_wal | 1/CF000158
postgres=# SELECT pid,usename,client_addr,state,write_lag,flush_lag,replay_lag FROM pg_stat_replication; 
-[ RECORD 1 ]----------------
pid         | 2176
usename     | repuser
client_addr | 192.168.59.172
state       | streaming
write_lag   | 00:00:00.000402
flush_lag   | 00:00:00.000697
replay_lag  | 00:02:02.77061
--可以看到这里的replay_log是
postgres=# select now(),* from test_delay;
ERROR:  relation "test_delay" does not exist
LINE 1: select now(),* from test_delay;
                            ^
postgres=# select now(),* from test_delay;
              now              | id |     create_time     
-------------------------------+----+---------------------
 2020-10-26 23:57:51.150388+08 |  1 | 2020-10-26 23:55:36
 这里也可以看到要2分钟后才能查询到