Re: pg_basebackup from cascading standby after timeline switch

On Tue, Dec 18, 2012 at 8:09 PM, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
> On 18 December 2012 00:53, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> Simon Riggs <simon(at)2ndQuadrant(dot)com> writes:
>>> On 17 December 2012 14:16, Heikki Linnakangas <hlinnakangas(at)vmware(dot)com> wrote:
>>>> I also wonder if pg_basebackup should
>>>> include *all* timeline history files in the backup, not just the latest one
>>>> strictly required to restore.
>>
>>> Why? the timeline history file includes the previous timelines already.
>>
>> The original intention was that the WAL archive might contain multiple
>> timeline files corresponding to various experimental recovery attempts;
>> furthermore, such files might be hand-annotated (that's why there's a
>> comment provision). So they would be at least as valuable from an
>> archival standpoint as the WAL files proper. I think we ought to just
>> copy all of them, period. Anything less is penny-wise and
>> pound-foolish.
>
> What I'm saying is that the new history file is created from the old
> one, so the latest file includes all the history as a direct copy. The
> only thing new is one line of information.

The timeline history file includes only ancestor timelines history. So
the latest one might not include all the history.

Regards,

--
Fujii Masao