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This article focuses on "how to achieve Postgresql stream replication active / standby switching", interested friends may wish to take a look. The method introduced in this paper is simple, fast and practical. Next let the editor to take you to learn "how to achieve Postgresql stream replication active / standby switching"!

-- operating system command to determine whether the sending process or the receiving process ps-ef | grep "wal" | grep-v "grep"-- data view select pid,usename,application_name,client_addr,state,sync_state from pg_stat_replication;--or slave library select pid,status,last_msg_send_time,last_msg_receipt_time,conninfo from pg_stat_wal_receiver;-- system function view select pg_is_in_recovery () -- Database control information pg_controldata | grep cluster-- view recovery.conf configuration file-- version before 9.0 trigger mode of master / slave switch file-- 1. Configure standby library file, add trigger_file parameter recovery.conftrigger_file='/pgdata/data/.postgresql.trigger.5432'--2, close main library pg_ctl stop-m fast--3, create trigger file, restart backup library Observe whether the recovery.conf becomes recovery.donetouch / pgdata/data/.postgresql.trigger.5432--4 and the old master library becomes the standby library-- edit the recovery.conf file recovery_target_timeline='latest'standby_mode=onprimary_conninfo='host=192.168.8.25 port=5432 user=repuser'-- password file cat .pgpass192.168.25: 5432:replication:repuser:re12a345192.168.8.81:5432:replication:repuser:re12a345chmod 0600 .pgpass-- switch the pg_ctl promote mode between the master and the slave-1, Close the main library pg_ctl stop-m fash--2, execute pg_ctl promote--3 for the standby library, switch the old master library to the standby library-- pg_rewind stream replication maintenance data synchronization tool-- when the standby library is activated as the master library If the old master library is not closed, then the old master library cannot be switched to a standby library and does not need to be re-backed up. Pg_rewind replication changes (incremental refresh synchronization)-- prerequisites can be met. 1. The wal_log_hints parameter in the postgresql.conf configuration file is set to on, and database 2 needs to be restarted.-- data-checksums is used during database installation, and io error is found. There is a loss in enabling performance-- node2 activation slave library-- node1 closes the slave library, and use pg_rewind incremental synchronization pg_rewind-- target-pgdata $PGDATA-- source-server='host=192.168.8.25 posrt=5432 user=postgres dbname=postgres'-P-- the above command is executed successfully The postgres user password will be written to ~ / .pgpass-- modify recovery.conf to start a new slave library-- delay the addition parameter of recovery.conf. Currently, it supports srecoverystarting minewriting application yearly delayflows 1min replication, delay parameter priority synchronous_commit=on recovery_min_apply_delay=1min # priority-remote_aplysynchronous_commit=remote_apply # main database operation blocked for 1 minute The result returned after the slave application is completed recovery_min_apply_delay=1min # priority-synchronous replication is preferably submitted with one master and two slaves. Note that when there is a downtime in the synchronous library, the primary database will block synchronous_standby_names=db1,db2 # the first slave library list is synchronous slave library, and the second potential synchronous slave library synchronous_standby_names='FIRST 2 (db1,db2,db3)'# the first two are synchronous slave library The third is the potential synchronization repository synchronous_standby_names='ANY 2 (db1,db2,db3)'# any two are the synchronization repository, and the other are the potential synchronization repository-cascade replication a > b > Cmure 1, asynchronous flow replication, deployment standby library b, replication is normal Start deploying the standby library C, execute-h apg_basebackup-D / pgdata/data-Fp-Xs-v-P-h 192.168.28.74-p 5432-U repuser--2, configure c recovery.conf file, host brecovery_target_timeline='latest'standby_mode=onprimary_conninfo='host=192.168.8.25 port=5432 user=repuser application_name=c'--3, start c so far, I believe you have a deeper understanding of "how to achieve Postgresql stream replication master / slave switch" You might as well do it in practice. Here is the website, more related content can enter the relevant channels to inquire, follow us, continue to learn!

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