Re: Controlling hot standby

On Fri, 2009-01-23 at 10:35 +0200, Heikki Linnakangas wrote:
> As the patch stands, there's no way to disable hot standby. The server 
> always opens for read-only connections as soon as it can. That might not 
> be what you want.
> 
> I think we need a GUC to enable/disable hot standby. It would become 
> handy if the unimaginable happens and there's a bug in the hot standby 
> code that prevents a server from recovering.

Currently recovery processing is only active during archive recovery,
never during crash recovery, for the above reason.

> I think we need a GUC to enable/disable hot standby. 

I presume you mean something that will stop us keeping track of
snapshots and preventing users from connecting?

Suggestion: hot_standby = on | off (on is default)
(in recovery.conf)

Would that include starting the bgwriter during recovery? Or should be a
separate boolean? If needed, should this be in postgresql.conf or in
recovery.conf?

Suggestion: bgwriter_during_recovery = on | off (on is default)
(in postgresql.conf)
If we do have this it may be deprecated in later releases if code is
stable and we have no reason to de-select this.

This second option will give us a performance boost and low failover
time, just without being able to run queries.

-- Simon Riggs           www.2ndQuadrant.comPostgreSQL Training, Services and Support