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From: Jonathan S. Katz <[email protected]>
To: Magnus Hagander <[email protected]>
Cc: Alvaro Herrera <[email protected]>
Cc: Pg Docs <[email protected]>
Cc: Bruce Momjian <[email protected]>
Subject: Re: retroactive pg10 relnotes: sequence changes
Date: Tue, 28 Aug 2018 13:43:03 -0400
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
References: <[email protected]>
	<CABUevEy3vxzC7w20R-SbMb1H0RMo6HprZXAhDrm7QbvVt2UCBQ@mail.gmail.com>
	<[email protected]>


> On Aug 28, 2018, at 1:09 PM, Jonathan S. Katz <[email protected]> wrote:
> 
> 
>> On Aug 28, 2018, at 1:02 PM, Magnus Hagander <[email protected] <mailto:[email protected]>> wrote:
>> 
>> 
>> 
>> On Tue, Aug 28, 2018 at 6:34 PM, Alvaro Herrera <[email protected] <mailto:[email protected]>> wrote:
>> Hello
>> 
>> A customer of ours was taken by surprise by a change in Postgres 10 on a
>> trial upgrade from 9.6.  They were using sequences from SERIAL columns a
>> little unorthodoxly, and their stuff stopped working: essentially, they
>> hacked the default expression so that it'd automatically use negative
>> numbers when the sequence reached INT_MAX.  Since pg10 changed sequences
>> to stop emitting values at that point, it raised an error rather than
>> emit the negative numbers.
>> 
>> (In 9.6 and prior, the sequence would emit values past INT_MAX; it was
>> the column that raised the error.  In pg10 things were changed so that
>> it is now the sequence that raises the error.)
>> 
>> My proposal now is to document this issue in the Postgres 10 release
>> notes.  "It's a little late for that!" I hear you say, but keep this in
>> mind: many users have *not* yet upgraded to 10, and they'll keep doing
>> it for years to come still.  So I disagree that now is too late.  We
>> failed to warn people that already upgraded, but we're still on time to
>> alert people yet to upgrade.
>> 
>> I attach both the patch and a screenshot to show how minor the visual
>> effect of the change is.
>> 
>> (If people hate this, another option is to make it a separate bullet
>> point.)
>> 
>> Looks reasonable to me. And I definitely think we should do it -- people will be upgrading to 10 for years to come, so claiming it's too late is definitely not correct.
> 
> +1.
> 
> I have attached patch where I suggested some alternate wording and
> remove the parenthetical comment, as I don’t believe that should be
> an aside.

Per off-list discussion from Bruce, re-attaching the patch. Apparently
it was only available in HTML mimepart. Hopefully this gets it into
the archives.

Jonathan




Attachments:

  [application/octet-stream] sequences-10-v2.patch (755B, 3-sequences-10-v2.patch)
  download | inline diff:
diff --git a/doc/src/sgml/release-10.sgml b/doc/src/sgml/release-10.sgml
index f1b0f2e0bf..09e5d0c593 100644
--- a/doc/src/sgml/release-10.sgml
+++ b/doc/src/sgml/release-10.sgml
@@ -4716,6 +4716,13 @@ Branch: REL_10_STABLE [5159626af] 2017-11-03 14:14:16 -0400
       more compatible with existing code.
      </para>
 
+     <para>
+      Also, sequences created for <literal>SERIAL</literal> columns now generate
+      positive 32-bit wide values, whereas previous versions generated 64-bit
+      wide values.  This has no visible effect if the values are only stored in
+      a column.
+     </para>
+
      <para>
       The output of <application>psql</application>'s <command>\d</command> command for a
       sequence has been redesigned, too.


  [application/pgp-signature] signature.asc (833B, 5-signature.asc)
  download

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