I have a Postgres 9.3 Master-Slave stream replication setup on Ubuntu.
I would like to just convert the Slave into read-write by breaking the replication. However, I do not want the Master to be impacted in any way, as its a critical Production. All I want is to have a clone of the Master, so that I can test pg_upgrade.
Can I just run a "pg_ctl promote" on the slave, and open the Slave for read/writes? Does running "pg_ctl promote" on the Slave have any impact on the Master?
Thanks very much.
from docs:
To trigger failover of a log-shipping standby server, run pg_ctl promote or create a trigger file with the file name and path specified by the trigger_file setting in recovery.conf. If you're planning to use pg_ctl promote to fail over, trigger_file is not required.
so both pg_ctl promote -D data_dir and touch trigger_file promote slave equally. Master is affected by slave being promoted in sense that sender stops sending. Other slaves streaming from master are affected in same manner. Promoting is a standard action.
The only specific case would be cascaded replication:
If an upstream standby server is promoted to become new master, downstream servers will continue to stream from the new master if recovery_target_timeline is set to 'latest'.
If you don't have any downstream "subslaves", promote it with courage.