From: Tom Lane <tgl@sss.pgh.pa.us>
To: "David G. Johnston" <david.g.johnston@gmail.com>
cc: glen.edmonds@gmail.com,
        PostgreSQL mailing lists <pgsql-bugs@lists.postgresql.org>
Subject: Re: BUG #17428: last_value incorrect for uninitialized sequence
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References: <17428-848dee31a3b899ab@postgresql.org>
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Comments: In-reply-to "David G. Johnston" <david.g.johnston@gmail.com>
	message dated "Mon, 07 Mar 2022 06:35:24 -0700"
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Date: Mon, 07 Mar 2022 09:48:05 -0500
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"David G. Johnston" <david.g.johnston@gmail.com> writes:
> On Mon, Mar 7, 2022 at 12:15 AM PG Bug reporting form <
> noreply@postgresql.org> wrote:
>> For a freshly defined sequence, the following:
>> select last_value from mytable_id_seq
>> should return 0, but returns 1.

> One seems as good a choice as zero if a non-null value is to be returned.

The larger point here is that any change is much more likely to
break applications expecting the historical behavior than it is
to make anyone's life better.  In a green field I'd tend to
agree that returning NULL (and dispensing with is_called) would
be a better design, but that opportunity was missed decades ago.

			regards, tom lane