Re: git: uh-oh

From: Max Bowsher <maxb(at)f2s(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Magnus Hagander <magnus(at)hagander(dot)net>, Robert Haas <robertmhaas(at)gmail(dot)com>, Michael Haggerty <mhagger(at)alum(dot)mit(dot)edu>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: git: uh-oh
Date: 2010-08-20 18:38:18
Message-ID: 4C6ECB9A.9090007@f2s.com
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On 20/08/10 19:30, Tom Lane wrote:
> Max Bowsher <maxb(at)f2s(dot)com> writes:
>> My guess at this point is that there may be a (very old?) version of cvs
>> which, when adding a file to a branch, actually misrecorded the file as
>> having existed on the branch from the moment it was first added to trunk
>> - this would explain this anomaly.
>
> I have no idea what version of CVS is running on our master server.
> I have noticed that it sometimes generates its own synthetic commit
> messages for cases related to this, for example these events on HEAD:
>
> 2010-05-13 12:40 adunstan
>
> * src/pl/plperl/sql/plperlu_plperl.sql: file plperlu_plperl.sql was
> initially added on branch REL8_4_STABLE.
>
> 2010-05-13 12:40 adunstan
>
> * src/pl/plperl/expected/plperlu_plperl.out: file
> plperlu_plperl.out was initially added on branch REL8_4_STABLE.

This is actually what's supposed to occur, and cvs2git will elide these
synthetic entries, which exist to represent the concept of adding a file
to a branch after the initial creation of the branch, within the fairly
arcane constraints of the RCS file format.

> I don't see one of these for plperl_opmask.pl in particular, so there
> may be more than one anomaly involved.

Just the one anomaly - the absence of one of those for plperl_opmask.pl
is the original anomaly.

> However, the bottom line here is that we don't want the history that
> cvs2git is preparing for these events, because it doesn't correspond to
> what we did. Whether this is the "most faithful" representation of the
> CVS history is academic; it simply is not reality. What we would like
> is for the history to look like the file got added to the branch as of
> the first commit that touched it on that branch. That is reality, as
> it appears from our neck of the woods anyway.

Michael, what's your take on this? I have a feeling that such a thing is
*not* going to be a quick hack in cvs2svn.

Max.

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