Message-ID: <45555a7a-f987-44d5-9f8a-593063f37ae2@yeah.net>
Date: Thu, 23 Oct 2025 08:19:46 +0800
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Subject: Re: Include extension path on pg_available_extensions
To: Matheus Alcantara <matheusssilv97@gmail.com>,
 Pg Hackers <pgsql-hackers@postgresql.org>
References: <DCTSKQAVOXIG.3A05JM1YORARK@gmail.com>
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From: Quan Zongliang <quanzongliang@yeah.net>
In-Reply-To: <DCTSKQAVOXIG.3A05JM1YORARK@gmail.com>
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On 9/16/25 8:18 AM, Matheus Alcantara wrote:

> Any opinions on this?
> 
> [1] https://www.postgresql.org/message-id/CAKFQuwbR1Fzr8yRuMW%3DN1UMA1cTpFcqZe9bW_-ZF8%3DBa2Ud2%3Dw%40mail.gmail.com
> 
Just as the discussion here. Adding extension location is a good idea.
Suppose there is an amcheck 1.5 located in the $system directory. There 
is also an amcheck 1.4.5 located in another path.

Strange results will then occur:
postgres=# SHOW extension_control_path;
  extension_control_path
------------------------
  $system
(1 row)

postgres=# CREATE EXTENSION amcheck;
CREATE EXTENSION
postgres=# select * from pg_available_extensions; 
  
                                name    | default_version | 
installed_version |                  comment                   | location
------------+-----------------+-------------------+--------------------------------------------+----------
  amcheck    | 1.5             | 1.5               | functions for 
verifying relation integrity | $system

This seems to be fine.

However, if another path is added, strange results will occur.

postgres=# SET extension_control_path TO 
'/Users/quanzl/build/pg-availext:$system';
SET
postgres=# select * from pg_available_extensions;
     name    | default_version | installed_version | 
comment                   |                 location
------------+-----------------+-------------------+--------------------------------------------+-------------------------------------------
  amcheck    | 1.4.5           | 1.5               | functions for 
verifying relation integrity | /Users/quanzl/build/pg-availext/extension

The results shown here will cause confusion. It is better to show the 
path used at creation.

So, it would be a better option to add a new column to the pg_extension 
table.

--
Quan Zongliang