From: Tom Lane <tgl@sss.pgh.pa.us>
To: haydenwillsim@gmail.com
cc: pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #18544: Setting local config_parameter to DEFAULT behaves
 unexpectedly when using period in config name
In-reply-to: <18544-60e74dd413b155f1@postgresql.org>
References: <18544-60e74dd413b155f1@postgresql.org>
Comments: In-reply-to PG Bug reporting form <noreply@postgresql.org>
	message dated "Thu, 18 Jul 2024 09:34:25 -0000"
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Date: Thu, 18 Jul 2024 09:55:18 -0400
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PG Bug reporting form <noreply@postgresql.org> writes:
> When a connection is initialised, calling `SELECT
> current_setting('hasura.user', 't');`, as expected will return a NULL.
> However if you call `SET "hasura.user" TO DEFAULT;`, this will actually
> intitialise the value to an empty string. 

That's a side effect of SET causing such a custom GUC to spring
into existence --- with an empty-string default, because there
is no better value.

> This presents a huge problem,

If you don't like it, don't use custom GUCs.  They're not officially
supported --- the only reason this is allowed at all is to allow
setting of an extension's GUCs before the extension is loaded.
See

https://www.postgresql.org/docs/current/runtime-config-custom.html

			regards, tom lane