From: Junio C Hamano <gitster@pobox.com>
Date: Wed, 13 Feb 2019 21:12:25 GMT
Subject: Re: How to get next commit that just after a specified commit
Message-ID: <xmqqimxnbdfq.fsf@gitster-ct.c.googlers.com>
In-Reply-To: <87mun0j9vv.fsf@evledraar.gmail.com>

Ævar Arnfjörð Bjarmason <avarab@gmail.com> writes:

> (Replying to
> https://public-inbox.org/git/383c14cc.9289.168e61d39e8.Coremail.wuzhouhui14@mails.ucas.ac.cn/
> which curiously I can see there, but not in my inbox (or spam))
>
> Git's data format doesn't make it easy to find "C" given "B" in a commit
> chain like A->B->C (also there could be any number of "C"
> successors). We need to walk the graph. This shows how to do it:
>
> https://sqlite.org/whynotgit.html#git_makes_it_difficult_to_find_successors_descendents_of_a_check_in

Of course, the history is not necessarily linear.  Even though you
*MUST* know all your parents before having a commit (which means
that when you ask "what came before this commit", there is a
definitive answer that everybody in the world would agree on), you
by definition cannot know all the commits that are children of a
commit (simply because somebody else may be creating a new one), so
the question "what's the next commit" does not make any sense from
that point of view ;-)