Postgresql - 检查数据库主从复制进度

如何查看主从复制的状态，且备库应用落后了多少字节

这些信息要在主库中查询

查看流复制的信息可以使用主库上的视图

select pid,state,client_addr,sync_priority,sync_state from pg_stat_replication;

pg_stat_replication中几个字断记录了发送wal的位置及备库接收到的wal的位置、

sent_location--发送wal的位置

write_location--备库接收到的wal的位置

flush_location—备库写wal日志到磁盘的位置

replay_location—备库应用日志的位置

查看备库落后主库多少字节

select pg_xlog_location_diff(pg_current_xlog_location(),replay_location)/1024/1024 as MB from pg_stat_replication;

select pg_xlog_location_diff(pg_current_xlog_location(),replay_location)/1024/1024/1024 as GB from pg_stat_replication;

级联复制

select pg_xlog_location_diff(pg_last_xlog_replay_location(),replay_location)/1024/1024/1024 as GB from pg_stat_replication;