Re: Clarification on when _PG_init() is invoked for extensions

From: Ayush Vatsa <ayushvatsa1810(at)gmail(dot)com>
To: Rahila Syed <rahilasyed90(at)gmail(dot)com>
Cc: PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Clarification on when _PG_init() is invoked for extensions
Date: 2025-11-20 17:52:41
Message-ID: CACX+KaMdJ7Avd945971cZQyD5dQF7ypJqrKL9dLSy45bNfkaYg@mail.gmail.com
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Hi,

CREATE extension does not automatically load or ensure that _PG_init() is
> run.
> It mainly runs the .sql script in your extension.
>
Thanks for the clarification. However, in my testing, _PG_init() did run
when I executed
CREATE EXTENSION. I suspect this might be happening because the SQL script
defines
C functions using MODULE_PATHNAME, which triggers the library load.
In a new session, _PG_init() seems to run again when any of those C
functions are executed.

*My use case:*
My use case is that I’m building an experimental extension that will be
installed only in a few
databases. I want the hooks initialized by this extension to apply only to
those specific
databases, while all other databases should continue with the default
PostgreSQL behavior.

Thank you,
Ayush

>

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