Oh, I didn't mean to imply that I am confused. It is clear that there are two 
concepts here, sharing a term. I was trying to communicate that the manual does 
not always make it immediately clear from context which concept is meant in a 
particular sentence.

A garage is a good analogy. A garage is a container for cars rather than a 
collection of cars. You wouldn't say "I sold my garage" to mean "I sold my car 
collection". Containers and collections are different things.

Here's a simple example In our context: "remove the cluster" could mean "delete 
the folder containing the databases", or "drop the databases". Those actions 
are not identical. I would think we would want to be clear to our users which 
we mean.

Paul

________________________________
From: David G. Johnston <david.g.johns...@gmail.com>
Sent: Friday, January 3, 2020 12:21 AM
To: lib...@hotmail.com <lib...@hotmail.com>; pgsql-docs@lists.postgresql.org 
<pgsql-docs@lists.postgresql.org>
Subject: Re: the concept of a database cluster

On Thursday, January 2, 2020, PG Doc comments form 
<nore...@postgresql.org<mailto:nore...@postgresql.org>> wrote:
The following documentation comment has been logged on the website:

Page: https://www.postgresql.org/docs/12/creating-cluster.html
Description:

In 18.2, a database cluster is said to be "a database storage area on disk",
and then shortly afterward is is defined as "a collection of databases that
is managed by a single instance of a running database server". Those seem
very different things. Sometimes in the manual I can't tell which usage is
intended.

A garage is a “car storage area for a house”. A garage can (typically) store 
multiple cars just as a database cluster can store multiple databases.  The 
files are only useful if there is a running instance and all databases stored 
in the cluster are managed by a single shared instance.  You will need to 
better explain your confusion because the documentation is describing a complex 
system accurately but in parts that are related - two sides of the same coin, 
if you will.

David J.

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