Re: Clean switchover

On Wed, Jun 12, 2013 at 9:48 PM, Stephen Frost <sfrost(at)snowman(dot)net> wrote:
> * Magnus Hagander (magnus(at)hagander(dot)net) wrote:
>> On Wed, Jun 12, 2013 at 1:48 PM, Andres Freund <andres(at)2ndquadrant(dot)com> wrote:
>> > On 2013-06-12 07:53:29 +0900, Fujii Masao wrote:
>> >> The attached patch fixes this problem. It just changes walsender so that it
>> >> waits for all the outstanding WAL records to be replicated to the standby
>> >> before closing the replication connection.
>> >
>> > Imo this is a fix that needs to get backpatched... The code tried to do
>> > this but failed, I don't think it really gives grounds for valid *new*
>> > concerns.
>>
>> +1 (without having looked at the code itself, it's definitely a
>> behaviour that needs to be fixed)
>
> Yea, I was also thinking it would be reasonable to backpatch this; it
> really looks like a bug that we're allowing this to happen today.
>
> So, +1 on a backpatch for me.

+1. I think that we can backpatch to 9.1, 9.2 and 9.3.

In 9.0, the standby doesn't send back any message to the master and
there is no way to know whether replication has been done up to
the specified location, so I don't think that we can backpatch.

One note is, even if we backpatch, controlled switchover may require
the backup in order to follow the timeline switch, in 9.1 and 9.2.
If we want to avoid the backup in that case, we need to set up
the shared archive area between the master and the standby and
set recovery_target_timeline to 'latest'.

Regards,

--
Fujii Masao