From: Johannes Schindelin <Johannes.Schindelin@gmx.de>
To: Richard Hipp <drh@sqlite.org>
Cc: git@vger.kernel.org
Subject: Re: git-fast-import yields huge packfile
Date: Thu, 21 Mar 2019 15:09:40 +0100 (STD) [thread overview]
Message-ID: <nycvar.QRO.7.76.6.1903211503030.41@tvgsbejvaqbjf.bet> (raw)
In-Reply-To: <CALwJ=MzrqPUNw=jc0NRtaJaJG+ErXNb577JNSN66GiGY4UFtRw@mail.gmail.com>
Hi Richard,
On Sat, 16 Mar 2019, Richard Hipp wrote:
> I'm trying to transform a repository from another VCS into a Git
> repository using "git fast-import". It appears to work, but the
> resulting Git repository is huge relative to the original - 18 times
> larger. Most of the space seems to be taken up by a single large
> packfile. That packfile is about 967 MB which is about 1/4th the
> total uncompressed size of all 41785 distinct Blobs in the original
> repository. The source VCS is able to compress this down to 52 MB by
> comparison.
I feel your pain, as I had the same problem back in the day. My use case
was mirroring an upstream Mercurial repository to a Git repository. This
use case went away, so I do not do that anymore (and there are more, less
happy reasons why I would no longer work on that git-remote-hg project,
but that's off topic). As one of the last rem(a)inders, Git for Windows
carries this patch:
https://github.com/git-for-windows/git/commit/b91911ff8d3e2cf279b4708be89de2e3bc8e9e87
Essentially, it *always* runs `git gc --auto` after running `fast-import`.
Which is a lot more high-level advice than the rather low-level `git
repack` hint given elsewhere in this thread.
Now, I wonder whether we should integrate this into `fast-import` proper
(with a knob to turn it off), maybe even offer to run `git gc --auto`
every <N> imported commits?
Ciao,
Johannes
> Maybe I'm doing something wrong with the fast-import stream that is
> defeating Git's attempts at delta compression....
>
> Are there any utility programs available for analyzing packfiles so
> that I try to figure out where the inefficiencies are cropping up, so
> that I can try to address them?
>
> Anybody have any suggestions on what I should be looking for?
>
> If anyone would care to see this oversized packfile and perhaps offer
> suggestions on how I can make it more space-efficient, it can be
> cloned from https://github.com/drhsqlite/fossil-mirror.git - at least
> for now - surely I will delete that repo and regenerate it once I
> figure out this problem.
>
> --
> D. Richard Hipp
> drh@sqlite.org
>
next prev parent reply other threads:[~2019-03-21 14:10 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-16 20:31 git-fast-import yields huge packfile Richard Hipp
2019-03-16 21:04 ` Linus Torvalds
2019-03-16 22:12 ` Mike Hommey
2019-03-16 23:22 ` Richard Hipp
2019-03-21 14:09 ` Johannes Schindelin [this message]
2019-03-21 14:23 ` Ævar Arnfjörð Bjarmason
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