Date: Thu, 3 Feb 2022 22:42:32 -0300
From: Alvaro Herrera <alvherre@alvh.no-ip.org>
To: Pavel Stehule <pavel.stehule@gmail.com>
Cc: Julien Rouhaud <rjuju123@gmail.com>,
	Swaha Miller <swaha.miller@gmail.com>,
	PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Subject: Re: support for CREATE MODULE
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On 2022-Feb-03, Pavel Stehule wrote:

> The biggest problem is coexistence of Postgres's SEARCH_PATH  object
> identification, and local and public scopes used in MODULEs or in Oracle's
> packages.
> 
> I can imagine MODULES as third level of database unit object grouping with
> following functionality
> 
> 1. It should support all database objects like schemas

I proposed a way for modules to coexist with schemas that got no reply,
https://postgr.es/m/202106021908.ddmebx7qfdld@alvherre.pgsql

I still think that that idea is valuable; it would let us create
"private" routines, for example, which are good for encapsulation.
But the way it interacts with schemas means we don't end up with a total
mess in the namespace resolution rules.  I argued that modules would
only have functions, and maybe a few other useful object types, but not
*all* object types, because we don't need all object types to become
private.  For example, I don't think I would like to have data types or
casts to be private, so they can only be in a schema and they cannot be
in a module.

Of course, that idea of modules would also ease porting large DB-based
applications from other database systems.

What do others think?

-- 
Álvaro Herrera              Valdivia, Chile  —  https://www.EnterpriseDB.com/