Subject: Re: Add A Glossary
To: Alvaro Herrera <alvherre@2ndquadrant.com>
Cc: Erik Rijkers <er@xs4all.nl>, Laurenz Albe <laurenz.albe@cybertec.at>,
 Fabien COELHO <coelho@cri.ensmp.fr>,
 Peter Eisentraut <peter.eisentraut@2ndquadrant.com>,
 Corey Huinker <corey.huinker@gmail.com>, Justin Pryzby
 <pryzby@telsasoft.com>, Roger Harkavy <rogerharkavy@gmail.com>,
 pgsql-hackers@postgresql.org, Michael Paquier <michael@paquier.xyz>
References: <20200517065126.GA20730@alvherre.pgsql>
From: =?UTF-8?Q?J=c3=bcrgen_Purtz?= <juergen@purtz.de>
Message-ID: <68649dfb-3c99-d5ca-2edc-e96f3848a890@purtz.de>
Date: Sun, 17 May 2020 10:09:48 +0200
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On 17.05.20 08:51, Alvaro Herrera wrote:
> Any object that
> exists in a database is local, regardless of whether it exists in a
> schema or not.
This implies that the term "local" is unnecessary, just call them "SQL 
object".
> "Extensions" is one type of object that does not belong
> in a schema.  "Foreign data wrapper" is another type of object that does
> not belong in a schema.  ...  They are*not*
> global objects.
postgres_fdw is a module among many others. It's only an example for 
"extensions" and has no different nature. Yes, they are not global SQL 
objects because they don't belong to the cluster.

In summary we have 3 types of objects: belonging to a schema, to a 
database, or to the cluster (global). Maybe, we can avoid the use of the 
different names 'local SQL object' and 'global SQL object' at all and 
just call them 'SQL object'. 'global SQL object' is used only once. We 
could rephrase "A set of databases and accompanying global SQL objects 
... " to "A set of databases and accompanying SQL objects, which exists 
at the cluster level, ... "

> TBH I'm not sure of this term at all.  I think we sometimes use the
> term "bloat" to talk about the dead rows only, ignoring the free space.

That's a good example for the necessity of the glossary. Currently we 
don't have a common understanding about all of our used terms. The 
glossary shall fix that and give a mandatory definition - after a 
clearing discussion.

--

Jürgen Purtz