From: Tom Lane <tgl@sss.pgh.pa.us>
To: =?GBK?B?tcK45w==?= <digoal@126.com>
cc: "David G. Johnston" <david.g.johnston@gmail.com>,
        "pgsql-bugs@lists.postgresql.org" <pgsql-bugs@lists.postgresql.org>
Subject: Re: BUG #17036: generated column cann't modifyed auto when update
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Comments: In-reply-to =?GBK?B?tcK45w==?= <digoal@126.com>
	message dated "Thu, 27 May 2021 17:21:34 +0800"
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Date: Thu, 27 May 2021 09:45:57 -0400
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=3D?GBK?B?tcK45w=3D=3D?=3D <digoal@126.com> writes:
> If the value of the immutable function changes, the immutable function s=
hould be recalculated.

You misunderstand completely.  An immutable marking on a function is a
promise from you to the system that the function's value does NOT change.
Therefore, the predicate of your statement is vacuous, and we need not
discuss whether the conclusion is interesting.  If there's some behavior
that you don't like as a consequence of your lie, then stop lying.

			regards, tom lane