From: Tom Lane <tgl@sss.pgh.pa.us>
To: Tomas Vondra <tomas@vondra.me>
cc: Tender Wang <tndrwang@gmail.com>, 503699317@qq.com,
        pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #18705: Segmentation fault when create brin index on
 user-defined type.
In-reply-to: <e47f0a40-f778-4165-90fb-3fa1be786234@vondra.me>
References: <18705-29cc90ff31682f19@postgresql.org>
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 <e47f0a40-f778-4165-90fb-3fa1be786234@vondra.me>
Comments: In-reply-to Tomas Vondra <tomas@vondra.me>
	message dated "Fri, 15 Nov 2024 16:38:45 +0100"
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Date: Fri, 15 Nov 2024 10:47:14 -0500
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Tomas Vondra <tomas@vondra.me> writes:
> On 11/15/24 07:17, Tender Wang wrote:
>> Can we report errors not crash if users pass an unexpected function?

Read up on the halting problem.

> I think it might be improved to do some checks, yes. The CREATE OPERATOR
> CLASS should be able to signatures of the functions - it's AM-specific,
> and there's a limit how much can be checked. For example these functions
> have "internal" arguments, which can be an arbitrary pointer.

We already have amvalidate, which would certainly have caught anything
as egregiously wrong as this example.  I do not remember why that's
not a forced step of CREATE OPERATOR CLASS, but I'm sure there
was a good reason for making it separate.

			regards, tom lane