Re: [ANNOUNCE] Example Cogito Addon - cogito-bundle

On Wed, 18 Oct 2006, Petr Baudis wrote:

By the way, originally I just wanted to index and save the pack, but
when trying to feed it to git-index-pack, I kept getting

	fatal: packfile '.git/objects/pack/pack-b2ab684daebea5b9c5a6492fa732e0d2e1799c8e.pack' has unresolved deltas

while feeding it to git-unpack-objects works fine. Any idea what's wrong?

Since you created a "thin" pack (that's what the "--objects-edge" means), 
the pack actually contains deltas to objects that are _not_ in the pack. 

In other words, it's not a valid stand-alone pack, it's only a valid thin 
pack, useful to transfer data to the other end (and the other end had 
better have the objects that the deltas are against already).

As a result, index-file refuses to index it: it cannot be used as a 
stand-alone pack, it's _only_ useful as a transfer medium.

So don't even _try_ to use it as a standalone pack-file. It won't work.

(If you want somethign that actually works as a stand-alone pack-file, 
change the "--objects-edge" flag to just "--objects" - that makes the 
pack-file self-sufficient, and doesn't try to delta against "edge" 
objects).

(BTW, I got the id by sha1summing the pack file; is there an existing
way to name a pack properly if I have it lying around, unnamed? sha1sum
seems to be specific to a fairly new GNU coreutils version.)

A properly named _standalone_ pack gets named not by its actual contents, 
but by the SHA1-sum of the sorted list of objects it contains. That's so 
that a pack-file will be named the same thing regardless of how the 
contents are actually packed.

A thin pack cannot be named that way at all, for the same reason you 
cannot index it: it has a set of objects it enumerates (so you could name 
it by them), but it _also_ has a set of objects outside of it that it 
depends on. 

That said, even a thin pack internally has a SHA1 checksum of its 
contents: the last 20 bytes should be the SHA1-sum of all preceding bytes. 
So if you just want _some_ kind of name, you can use the last 20 bytes of 
a pack, which is just its internal integrity-checksum (but that is 
_different_ from the "pack-xxxxxx.idx"/"pack-xxxxxx.pack" naming).

			Linus