From mboxrd@z Thu Jan  1 00:00:00 1970
From: ludo@gnu.org (Ludovic =?UTF-8?Q?Court=C3=A8s?=)
Subject: bug#20137: number of generation doesn't always rise monotonically
Date: Wed, 18 Mar 2015 21:36:26 +0100
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References: <20150318173550.GE525@venom.suse.cz>
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	("=?UTF-8?Q?Tom=C3=A1=C5=A1_?= =?UTF-8?Q?=C4=8Cech?="'s message of
	"Wed, 18 Mar 2015 18:35:51 +0100")
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Tom=C3=A1=C5=A1 =C4=8Cech <sleep_walker@gnu.org> skribis:

> 1] install some package (you'll have N and N+1)
> 2] install some other package (you'll have N, N+1 and N+2)
> 3] delete generation N+1 (you'll have N and N+2)
> 4] switch to generation N
> 5] install some package - you'll get generation N+1 again
>   (you'll have N, N+1 and N+2 again)

That=E2=80=99s expected, yes.  What makes you think it=E2=80=99s a problem?

When implementing that, there were several possible choices:

  1. Upon rollback to N, remove all generations above N.  Rejected
     because it gratuitously prevents useful use cases.

  2. Upon rollback from P to N, keep all the generations, but use P+1
     for the next generation number.  Doesn=E2=80=99t work, because rolling=
 back
     from P+1 would bring you back to P instead of N.

  3. The current behavior.

See <http://lists.gnu.org/archive/html/bug-guix/2013-01/msg00325.html>
for part of the discussion.

Thanks,
Ludo=E2=80=99.