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syncasyncpotential
1个 primary, 3个 standby.
postgresql.confsynchronous_standby_names = 'test1,test2,test3'standby1配置
primary_conninfo = 'application_name=test1 host=127.0.0.1 port=1999 user=postgres keepalives_idle=60'standby2配置
primary_conninfo = 'application_name=test2 host=127.0.0.1 port=1999 user=postgres keepalives_idle=60'standby3配置
primary_conninfo = 'application_name=test3 host=127.0.0.1 port=1999 user=postgres keepalives_idle=60'primary查询
digoal=# select pid,application_name,client_addr,sync_state from pg_stat_replication; pid | application_name | client_addr | sync_state ------+------------------+-------------+------------ 6311 | test1 | 127.0.0.1 | sync 6321 | test2 | 127.0.0.1 | potential 6391 | test3 | 127.0.0.1 | potential(3 rows)如果sync节点挂掉, 按synchronous_standby_names的顺序, 第一个potential节点会变成sync状态.
pg_ctl stop -m fast -D /pgdata11999digoal=# select pid,application_name,client_addr,sync_state from pg_stat_replication; pid | application_name | client_addr | sync_state ------+------------------+-------------+------------ 6564 | test2 | 127.0.0.1 | sync 6568 | test3 | 127.0.0.1 | potential(2 rows)当test1重新起来后又会变成sync状态.
pg93@db-172-16-3-33-> pg_ctl start -D /pgdata11999server startingdigoal=# select pid,application_name,client_addr,sync_state from pg_stat_replication; pid | application_name | client_addr | sync_state ------+------------------+-------------+------------ 6564 | test2 | 127.0.0.1 | potential 6605 | test1 | 127.0.0.1 | sync 6568 | test3 | 127.0.0.1 | potential(3 rows)
synchronous_standby_names = 'test1,test2'
digoal=# select pid,application_name,client_addr,sync_state from pg_stat_replication; pid | application_name | client_addr | sync_state ------+------------------+-------------+------------ 6470 | test1 | 127.0.0.1 | sync 6472 | test3 | 127.0.0.1 | async 6474 | test2 | 127.0.0.1 | potential(3 rows)
synchronous_standby_names = 'test1'
digoal=# select pid,application_name,client_addr,sync_state from pg_stat_replication; pid | application_name | client_addr | sync_state ------+------------------+-------------+------------ 6519 | test2 | 127.0.0.1 | async 6521 | test3 | 127.0.0.1 | async 6523 | test1 | 127.0.0.1 | sync(3 rows)
/* * Returns activity of walsenders, including pids and xlog locations sent to * standby servers. */Datumpg_stat_get_wal_senders(PG_FUNCTION_ARGS){...略 /* * More easily understood version of standby state. This is purely * informational, not different from priority. */ if (sync_priority[i] == 0) values[7] = CStringGetTextDatum("async"); else if (i == sync_standby) values[7] = CStringGetTextDatum("sync"); else values[7] = CStringGetTextDatum("potential");...略 转载地址：http://pymja.baihongyu.com/