Re: [GENERAL] RE: [GENERAL] Re: [GENERAL] A simple extension immitating pg_notify‏

> On 26 Jul 2016, at 2:52, Mehran Ziadloo <mehran20@hotmail.com> wrote:
>
> Sorry if my terminology is not accurate. But by an instance, I mean a PostgreSQL
> installation. And I call it an instance (and not a database) not to confuse it
> with the concept of databases (as in databases / schemas). Even when I'm trying
> to clarify the terminology, it's hard due to lack of distinguishable words!
>
> And here, I'm not talking about the cluster version of PostgreSQL. Simple, old
> fashion PostgreSQL will do.

Nobody here is talking about some clustered version of PG.

What you call an 'instance' (or 'installation') is called a cluster. A cluster contains databases, which contain
schema'setc. In database terms, a cluster is a single database server, a single 'installation' in your terms. 

If you would install multiple PG servers in separate directories, running on separate port numbers, you would have
multipleclusters. Same if you distribute those servers over several hosts, what you seem to think a cluster means. That
isthe difference between a cluster of databases and a cluster of servers. 

Alban Hertroys
--
If you can't see the forest for the trees,
cut the trees and you'll find there is no forest.