2017-03-19 17:52 GMT+13:00 lin <jlu...@163.com>: > Hi, > everyone. I am puzzled > <https://www.baidu.com/link?url=jInEDezMLuMV_corXvCP8CETViLH7RBG45m-C91WcPScwzYDdIWsiKilkG-4jIwgFGyxoIYaKbkbt5ijJc4m1qnl5ESOYdXggHLBeBmpDmC&wd=&eqid=b06a8963001f680e0000000358ce0b14> > about > the question: the master A has two slave slave_1 , slave_2 , the version of > postgres is 9.3. I want to promote one slave to master, and the other slave > as the new master's slave, but which slave should can promote ? > > get the master-slave information from old master: > postgres=# select * from pg_stat_replication; > -[ RECORD 1 ]----+------------------------------ > pid | 15377 > usesysid | 10 > usename | postgres > *application_name | slave_1* > client_addr | 10.20.16.201 > client_hostname | > client_port | 46086 > backend_start | 2017-03-19 12:42:02.026278+08 > state | streaming > sent_location | 1/34FB0000 > write_location | 1/34EB0000 > flush_location | 1/34DB0000 > replay_location | 1/34C4FFD8 > sync_priority | 0 > sync_state | async > -[ RECORD 2 ]----+------------------------------ > pid | 15411 > usesysid | 10 > usename | postgres > *application_name | slave_2* > client_addr | 10.20.16.200 > client_hostname | > client_port | 51102 > backend_start | 2017-03-19 12:42:12.477886+08 > state | streaming > sent_location | 1/414FD320 > write_location | 1/414FD320 > flush_location | 1/414FD320 > replay_location | 1/3DD91468 > sync_priority | 0 > sync_state | async > > 1. which one can promote to master ,slave_1 or slave_2 ? > :: I think it is slave_2, because write_location slave_2 1/414FD320 > > slave_1 (1/34FB0000), it is right? > > 2. If the slave_1 is sync state, which one can promote to master? I am > puzzled. > > You can promote any slave server to become a master server. It's up to you which one to do it; more info can be found here [1].
*Example:* slave_1 will be the new master and slave_2 will be the slave of that new master. Make sure to have all the wal files and history files copied to the slave_2 server otherwise it won't be able to switch timeline. [1] https://www.postgresql.org/docs/9.3/static/warm-standby-failover.html Lucas
