Postgresql 检查数据库主从复制进度的操作
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
selectpid,state,client_addr,sync_priority,sync_statefrompg_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
selectpg_xlog_location_diff(pg_current_xlog_location(),replay_location)/1024/1024asMBfrompg_stat_replication; selectpg_xlog_location_diff(pg_current_xlog_location(),replay_location)/1024/1024/1024asGBfrompg_stat_replication;
级联复制
selectpg_xlog_location_diff(pg_last_xlog_replay_location(),replay_location)/1024/1024/1024asGBfrompg_stat_replication;
补充:pgsql之查看主备复制延迟
查看复制延迟:
10.0及以上:
SELECT pg_wal_lsn_diff(A.c1,replay_lsn)/(1024*1024)ASslave_latency_MB, pg_wal_lsn_diff(A.c1,sent_lsn)/(1024*1024)ASsend_latency_MB, pg_wal_lsn_diff(A.c1,flush_lsn)/(1024*1024)ASflush_latency_MB, state, backend_start, now()::timestampwithtimezone FROMpg_stat_replication,pg_current_wal_lsn()ASA(c1) WHEREclient_addr='192.168.46.173'andapplication_name='standby1' ORDERBYslave_latency_MB,send_latency_MBDESC LIMIT1;
注:
192.168.46.173表示从库ip地址。
pg_wal_lsn_diff(lsnpg_lsn,lsnpg_lsn):计算两个预写式日志位置间的差别。
pg_current_wal_lsn():获得当前预写式日志写入位置
小于10.0版本:
SELECT pg_xlog_location_diff(A.c1,replay_lsn)/(1024*1024)ASslave_latency_MB, pg_xlog_location_diff(A.c1,sent_lsn)/(1024*1024)ASsend_latency_MB, pg_xlog_location_diff(A.c1,flush_lsn)/(1024*1024)ASflush_latency_MB, state, backend_start, now()::timestampwithtimezone FROMpg_stat_replication,pg_current_xlog_locationASA(c1) WHEREclient_addr='192.168.46.173'andapplication_name='standby1' ORDERBYslave_latency_MB,send_latency_MBDESC LIMIT1;
注:
192.168.46.173表示从库ip地址。
pg_xlog_location_diff(lsnpg_lsn,lsnpg_lsn):计算两个预写式日志位置间的差别。
pg_current_xlog_location():获得当前预写式日志写入位置
以上为个人经验,希望能给大家一个参考,也希望大家多多支持毛票票。如有错误或未考虑完全的地方,望不吝赐教。