Re: pg_system_identifier()

On 2013-08-22 21:51:22 +0900, Fujii Masao wrote:
> On Thu, Aug 22, 2013 at 6:43 AM, Vik Fearing <vik(dot)fearing(at)dalibo(dot)com> wrote:
> > After someone in IRC asked if there was an equivalent to MySQL's
> > server_id, it was noted that we do have a system identifier but it's not
> > very accessible.
> >
> > The attached patch implements a pg_system_identifier() function that
> > exposes it.
>
> What's the use case?
>
> IIUC, PostgreSQL's system identifier is not equal to MySQL server-id.
> In PostgreSQL, in replication, the master and all the standbys must
> have the same system identifier. OTOH, in MySQL, they have the different
> server-ids. No?

FWIW I've wished for that function repeatedly. Mostly just to make sure
I am actually connected to the same "network" of replicas and not some
other.
It's also useful if you're providing support for a limited number of
machines and you want some form of identifying a node.

Greetings,

Andres Freund

--
Andres Freund http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services