| From: | "Pavan Deolasee" <pavan(dot)deolasee(at)gmail(dot)com> |
|---|---|
| To: | "Heikki Linnakangas" <heikki(dot)linnakangas(at)enterprisedb(dot)com> |
| Cc: | "Fujii Masao" <masao(dot)fujii(at)gmail(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: How should pg_standby get over the gap of timeline? |
| Date: | 2008-11-20 15:15:21 |
| Message-ID: | 2e78013d0811200715q36ab6ab5x8ec03fa2d712157c@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Thu, Nov 20, 2008 at 8:36 PM, Heikki Linnakangas <
heikki(dot)linnakangas(at)enterprisedb(dot)com> wrote:
>
> That seems like a dangerous assumption. What if the standby had fallen
> behind before the failover? It's not safe to failover back to the original
> primary in that case. We'd need some kind of safeguards against that.
>
>
For synchronous replication, what if we ensure that the standby has received
the WAL (atleast in its buffers) before writing it to disk on the primary ?
If we do that, I think the old standby can never fall behind the primary and
it would be easy for the old primary to join back the replication without a
fresh backup.
Of course, this doesn't work for async replication.
Thanks,
Pavan
--
Pavan Deolasee
EnterpriseDB http://www.enterprisedb.com
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