Re: Synchronous replication question

On Tue, Jul 7, 2015 at 1:45 PM, CS DBA <cs_dba(at)consistentstate(dot)com> wrote:

> All;
>
> The docs specify this (9.4 docs):
>
> Synchronous replication offers the ability to confirm that all changes
> made by a transaction have been transferred to *one* synchronous standby
> server. This extends the standard level of durability offered by a
> transaction commit. This level of protection is referred to as 2-safe
> replication in computer science theory.
>
> Does this mean that Synchronous replication only works with one standby?
>
> Thanks in advance
>

No, it means that it requires, at minimum, one standby to confirm that the
transaction has been committed there before the master confirms it back to
the client. Look at this section of the docs

http://www.postgresql.org/docs/9.4/static/warm-standby.html#SYNCHRONOUS-REPLICATION
http://www.postgresql.org/docs/9.4/static/runtime-config-replication.html#GUC-SYNCHRONOUS-STANDBY-NAMES