On 31 March 2017 at 12:49, Craig Ringer <craig@2ndquadrant.com> wrote:
> On 31 March 2017 at 01:16, Andres Freund <andres@anarazel.de> wrote:
>> The comment and code don't quite square to me - it's far from obvious
>> that LogStandbySnapshot does something like that. I'd even say it's a
>> bad idea to have it do that.
>
> So you prefer the prior approach with separate xl_catalog_xmin advance records?
Alternately, we can record the creation timeline on slots, so we know
if there's been a promotion. It wouldn't make sense to do this if that
were the only use of timelines on slots. But I'm aware you'd rather
keep slots timeline-agnostic and I tend to agree.
Anyway, per your advice will split out the validation step.
(I'd like replication origins to be able to track time alongside lsn,
and to pass the timeline of each LSN to output plugin callbacks so we
can detect if a physical promotion results in us backtracking down a
fork in history, but that doesn't affect slots.)
-- Craig Ringer http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training & Services