Postgresql 檢查數(shù)據(jù)庫主從復制進度的操作

更新時間：2020年12月30日 15:42:27 作者：ChuckChen1222

這篇文章主要介紹了Postgresql 檢查數(shù)據(jù)庫主從復制進度的操作，具有很好的參考價值，希望對大家有所幫助。一起跟隨小編過來看看吧

如何查看主從復制的狀態(tài)，且備庫應用落后了多少字節(jié)

這些信息要在主庫中查詢

查看流復制的信息可以使用主庫上的視圖

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

pg_stat_replication中幾個字斷記錄了發(fā)送wal的位置及備庫接收到的wal的位置、

sent_location--發(fā)送wal的位置

write_location--備庫接收到的wal的位置

flush_location—備庫寫wal日志到磁盤的位置

replay_location—備庫應用日志的位置

查看備庫落后主庫多少字節(jié)

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;

級聯(lián)復制

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

補充：pgsql之查看主備復制延遲

查看復制延遲：

10.0及以上：

SELECT 
  pg_wal_lsn_diff(A .c1, replay_lsn) /(1024 * 1024) AS slave_latency_MB,
  pg_wal_lsn_diff(A .c1, sent_lsn) /(1024 * 1024) AS send_latency_MB,
  pg_wal_lsn_diff(A .c1, flush_lsn) /(1024 * 1024) AS flush_latency_MB,
  state,
  backend_start,
  now()::timestamp with time zone
 FROM pg_stat_replication, pg_current_wal_lsn() AS A(c1)
 WHERE client_addr='192.168.46.173' and application_name = 'standby1'
 ORDER BY slave_latency_MB, send_latency_MB DESC
 LIMIT 1;

注：

192.168.46.173 表示從庫ip地址。

pg_wal_lsn_diff(lsn pg_lsn, lsn pg_lsn):計算兩個預寫式日志位置間的差別。

pg_current_wal_lsn()：獲得當前預寫式日志寫入位置

小于10.0版本：

SELECT 
  pg_xlog_location_diff(A .c1, replay_lsn) /(1024 * 1024) AS slave_latency_MB,
  pg_xlog_location_diff(A .c1, sent_lsn) /(1024 * 1024) AS send_latency_MB,
  pg_xlog_location_diff(A .c1, flush_lsn) /(1024 * 1024) AS flush_latency_MB,
  state,
  backend_start,
  now()::timestamp with time zone
 FROM pg_stat_replication, pg_current_xlog_location AS A(c1)
 WHERE client_addr='192.168.46.173' and application_name = 'standby1'
 ORDER BY slave_latency_MB, send_latency_MB DESC
 LIMIT 1;

注：

192.168.46.173 表示從庫ip地址。

pg_xlog_location_diff(lsn pg_lsn, lsn pg_lsn):計算兩個預寫式日志位置間的差別。

pg_current_xlog_location ()：獲得當前預寫式日志寫入位置

以上為個人經驗，希望能給大家一個參考，也希望大家多多支持腳本之家。如有錯誤或未考慮完全的地方，望不吝賜教。

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