Re: Hot standby and b-tree killed items

Simon Riggs wrote:
> On Sat, 2008-12-20 at 09:21 +0200, Heikki Linnakangas wrote:
>> Gregory Stark wrote:
>>> Simon Riggs <simon(at)2ndQuadrant(dot)com> writes:
>>>
>>>> Increasing the waiting time increases the failover time and thus
>>>> decreases the value of the standby as an HA system. Others value high
>>>> availability higher than you and so we had agreed to provide an option
>>>> to allow the max waiting time to be set.
>>> Sure, it's a nice option to have. But I think the default should be to pause
>>> WAL replay.
>> I think I agree that pausing should be the default. If for no other
>> reason, because I can't think of a good default for max_standby_delay.
>
> I would rather err on the side of caution. If we do as you suggest,
> somebody will lose their database and start shouting "stupid default".

Even if we stop applying the WAL, it should still be archived safely,
right? So no data should be lost, although the standby can fall very
much behind, and it can take a while to catch up.

> So I would suggest we set it to say 5 seconds to start with and let
> people that read the manual set it higher, or at least read the manual
> after they receive their first query cancellation.

I don't feel strongly either way...

--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com