Re: Changing the setting of wal_sender_timeout per standby

On Thu, Sep 13, 2018 at 01:14:12AM +0000, Tsunakawa, Takayuki wrote:
> Some customer wants to change the setting per standby, i.e., a shorter
> timeout for a standby in the same region to enable faster detection
> failure and failover, and a longer timeout for a standby in the remote
> region (for disaster recovery) to avoid mis-judging its health.

This argument is sensible.

> The current PGC_HUP allows to change the setting by editing
> postgresql.conf or ALTER SYSTEM and then sending SIGHUP to a specific
> walsender.  But that's not easy to use.  The user has to do it upon
> every switchover and failover. 
> 
> With PGC_BACKEND, the user would be able to tune the timeout as follows:
> 
> [recovery.conf]
> primary_conninfo = '... options=''-c wal_sender_timeout=60000'' ...'
> 
> With PGC_USERSET, the user would be able to use different user
> accounts for each standby, and tune the setting as follows: 
> 
> ALTER USER repluser_remote SET wal_sender_timeout = 60000;

It seems to me that switching to PGC_BACKENDwould cover already all the
use-cases you are mentioning, as at the end one would just want to
adjust the WAL sender timeout on a connection basis depending on the
geographical location of the receiver and the latency between primary
and standby.
--
Michael