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From: "Ben Peart" <>
To: "'Stefan Beller'" <>,
	"'Martin Fick'" <>
Cc: "'Shawn Pearce'" <>,
	"'git'" <>, <>
Subject: RE: [RFC] Add support for downloading blobs on demand
Date: Wed, 18 Jan 2017 13:27:09 -0500	[thread overview]
Message-ID: <002801d271b8$7b909600$72b1c200$> (raw)
In-Reply-To: <>

We actually pursued trying to make submodules work for some time and 
even built tooling around trying to work around some of the issues we 
ran into (not but along a similar line) before determining that 
we would be better served by having a single repo and solving the scale 
issues.  I don't want to rehash the arguments for/against a single repo 
- suffice it to say, we have opted for a single large repo. :)


> -----Original Message-----
> From: Stefan Beller []
> Sent: Tuesday, January 17, 2017 5:24 PM
> To: Martin Fick <>
> Cc: Ben Peart <>; Shawn Pearce
> <>; git <>;
> Subject: Re: [RFC] Add support for downloading blobs on demand
> On Tue, Jan 17, 2017 at 2:05 PM, Martin Fick <>
> wrote:
> > On Tuesday, January 17, 2017 04:50:13 PM Ben Peart wrote:
> >> While large files can be a real problem, our biggest issue today is
> >> having a lot (millions!) of source files when any individual
> >> developer only needs a small percentage of them.  Git with 3+ million
> >> local files just doesn't perform well.
> >
> > Honestly, this sounds like a problem better dealt with by using git
> > subtree or git submodules, have you considered that?
> >
> > -Martin
> >
> I cannot speak for subtrees as I have very little knowledge on them.
> But there you also have the problem that *someone* has to have a whole
> tree? (e.g. the build bot)
> submodules however comes with a couple of things attached, both positive
> as well as negative points:
> * it offers ACLs along the way. ($user may not be allowed to
>   clone all submodules, but only those related to the work)
> * The conceptual understanding of git just got a lot harder.
>   ("Yo dawg, I heard you like git, so I put git repos inside
>   other git repos"), it is not easy to come up with reasonable
>   defaults for all usecases, so the everyday user still has to
>   have some understanding of submodules.
> * typical cheap in-tree operations may become very expensive:
>   -> moving a file from one location to another (in another
>      submodule) adds overhead, no rename detection.
> * We are actively working on submodules, so there is
>   some momentum going already.
> * our experiments with Android show that e.g. fetching (even
>   if you have all of Android) becomes a lot faster for everyday
>   usage as only a few repositories change each day). This
>   comparision was against the repo tool, that we currently
>   use for Android. I do not know how it would compare against
>   single repo Git, as having such a large repository seemed
>   complicated.
> * the support for submodules in Git is already there, though
>   not polished. The positive side is to have already a good base,
>   the negative side is to have support current use cases.
> Stefan

  reply	other threads:[~2017-01-18 18:57 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-01-13 15:52 [RFC] Add support for downloading blobs on demand Ben Peart
2017-01-13 21:07 ` Shawn Pearce
2017-01-17 21:50   ` Ben Peart
2017-01-17 22:05     ` Martin Fick
2017-01-17 22:23       ` Stefan Beller
2017-01-18 18:27         ` Ben Peart [this message]
2017-01-17 18:42 ` Jeff King
2017-01-17 21:50   ` Ben Peart
2017-02-05 14:03     ` Christian Couder
2017-02-07 18:21       ` Ben Peart
2017-02-07 21:56         ` Jakub Narębski
2017-02-08  2:18           ` Ben Peart
2017-02-23 15:39         ` Ben Peart

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