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git clone ignores GIT_ALTERNATE_OBJECT_DIRECTORIES

Subject: git clone ignores GIT_ALTERNATE_OBJECT_DIRECTORIES

## tl;dr

3 messages between Jul 30, 2009 and Jul 31, 2009.

replies: 2people: 2as markdown or json

Brian Ristuccia· Jul 30, 2009, 17:58 UTC · lore

When running git clone, it seems that GIT_ALTERNATE_OBJECT_DIRECTORIES is not considered. Even though most of the needed objects are in GIT_ALTERNATE_OBJECT_DIRECTORIES, I still wind up with a ton of traffic over the network and a huge .git/objects hierarchy.

Running "git gc" later pares down the .git/objects to a more reasonable size, so it seems the problem is limited to git clone. Using "git clone --reference" also seems to do the right thing.

Is this behavior intentional for some good reason I've overlooked, or have I stumbled on a bug?

-- 
Brian Ristuccia
brian@ristuccia.com
Junio C Hamano· Jul 30, 2009, 20:04 UTC · re: Brian Ristuccia · lore

Re: git clone ignores GIT_ALTERNATE_OBJECT_DIRECTORIES

Brian Ristuccia <brian@ristuccia.com> writes:
> Is this behavior intentional for some good reason I've overlooked, or have I
> stumbled on a bug?
Most likely not a bug.

When you talk about "clone", you need to realize that there actually are two repositories (and two object databases) involved: cloned source and destination.

Which repository should GIT_ALTERNATE_OBJECT_DIRECTORIES affect?

If you are making a clone from a remote over the network, and if you already have another local repository of a related project that has necessary objects, you may want to look at

    "git clone --reference"
Brian Ristuccia· Jul 31, 2009, 12:55 UTC · re: Junio C Hamano · lore

Re: git clone ignores GIT_ALTERNATE_OBJECT_DIRECTORIES

On Thu, Jul 30, 2009 at 01:04:31PM -0700, Junio C Hamano wrote:
Show 13 quoted lines
> Brian Ristuccia <brian@ristuccia.com> writes:
> 
> > Is this behavior intentional for some good reason I've overlooked, or have I
> > stumbled on a bug?
> 
> Most likely not a bug.
> 
> When you talk about "clone", you need to realize that there actually are
> two repositories (and two object databases) involved: cloned source and
> destination.
> 
> Which repository should GIT_ALTERNATE_OBJECT_DIRECTORIES affect?
>

Whichever one git is currently working in. (Even if git picks the "wrong" repository, object f1d2d2f924e986ac86fdf7b36c94bcdf32beec15 is still f1d2d2f924e986ac86fdf7b36c94bcdf32beec15 regardless of which repo it appears in and the end result will be consistent). 

My understanding after reading gitrepository-layout(5), git-fsck(1),  is
that the effect of listing a directory in GIT_ALTERNATE_OBJECT_DIRECTORIES
should be roughly the same as listing it in the .git/objects/info/alternates
of whatever repository git happens to be working on.
Show 6 quoted lines
> If you are making a clone from a remote over the network, and if you
> already have another local repository of a related project that has
> necessary objects, you may want to look at
> 
>     "git clone --reference"
>

Yes, this does the right thing as I mentioned in my previous message. (Behind the scenes, it's setting up .git/objects/info/alternates). My question is why doesn't GIT_ALTERNATE_OBJECT_DIRECTORIES behave the same as .git/objects/info/alternatives in all cases?

-- 
Brian Ristuccia
brian@ristuccia.com

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