Re: Replication failure, slave requesting old segments

Greetings,

* Phil Endecott (spam_from_pgsql_lists(at)chezphil(dot)org) wrote:
> Adrian Klaver wrote:
> >On 08/12/2018 03:54 PM, Stephen Frost wrote:
> >>Greetings,
> >>
> >>* Phil Endecott (spam_from_pgsql_lists(at)chezphil(dot)org) wrote:
> >>>OK. I think this is perhaps a documentation bug, maybe a missing
> >>>warning when the master reads its configuration, and maybe (as you say)
> >>>a bad default value.
> >>
> >>If we consider it to be an issue worthy of a change then we should
> >>probably just change the default value, and maybe not even allow it to
> >>be set lower than '1'.
> >
> >I would say leave the default at 0 as it leaves no doubt that you are
> >performing without a net. A setting of '1' implies you are covered and for
> >a fast moving cluster or slow moving one with sufficient downtime that
> >would not be the case.
>
> Can you explain how it can fail in the case of a "slow moving cluster with
> sufficient downtime"?

I'm guessing 'sufficient downtime' here is, basically, 'offline until
the next checkpoint', which isn't actually all *that* much time.

> It seems to me that if I have correctly understood what happened in this
> case then 0, the default, really cannot ever work properly when you have
> enabled WAL archiving plus streaming.

Well, it's not like it'd work without WAL archiving either, though
that's perhaps more obviously true.

Thanks!

Stephen