Re: Keeping unreachable objects in a separate pack instead of loose?

["Hallvard B Furuseth" <h.b.furuseth@usit.uio.no>]

On Sun, June 10, 2012 14:31, Theodore Ts'o wrote:
> I recently noticed that after a git gc, I had a huge number of loose
> objects that were unreachable.  In fact, about 4.5 megabytes worth of
> objects.

I got gigabytes once, and a full disk.  See thread
"git gc == git garbage-create from removed branch", May 3 2012.

> When I packed them, via:
>
>    cd .git/objects ; find [0-9a-f][0-9a-f] -type f | git pack-objects pack
>
> the resulting pack file was 244k.
>
> Which got me thinking.... the whole point of leaving the objects loose
> is to make it easier to expire them, right?   But given how expensive it
> is to have loose objects lying around, why not:
>
> a)  Have git-pack-objects have an option which writes the unreachable
>     objects into a separate pack file, instead of kicking them loose?

I think this should be the default.  It's very unintuitive that
gc can eat up lots of disk space instead of saving space.

Until this is fixed, this behavior needs to be documented -
along with how to avoid it.

> b)  Have git-prune delete a pack only if *all* of the objects in the
>     pack meet the expiry deadline?
>
> What would be the downsides of pursueing such a strategy?  Is it worth
> trying to implement as proof-of-concept?

Hallvard