Re: [RFC PATCH] multi-pack-index: allow operating without pack files

From: Johannes Berg <johannes@sipsolutions.net>
Date: Aug 23, 2021, 08:21 UTC
Message-ID: <dc146642f6aa9ac49d02cca47779071258e7541e.camel@sipsolutions.net>
In-Reply-To: <3649958.14eQuSAvaI@mfick-lnx>

On Sun, 2021-08-22 at 19:11 -0600, Martin Fick wrote:

Show 12 quoted lines

> On Sunday, August 22, 2021 8:34:43 PM MDT Derrick Stolee wrote:
> > On 8/20/2021 3:55 PM, Johannes Berg wrote:
> > > Technically, multi-pack-index doesn't need pack files to exist,
> > > but add_packed_git() today checks whether it exists or not.
> > 
> > Having a multi-pack-index is supposed to indicate that we have
> > these objects in the objects/pack directory within the specified
> > pack-files.
> 
> Hmm, isn't it a normal supported use case for repacking to potentially delete 
> packfiles which are in the MIDX (I'm specifically thinking about when someone 
> runs git gc with an older git version which knows nothing about MIDX files)?

Yeah, the multi-pack-index contains all the pack names that are there (and then which one the object is in), and when git tries to use it, then it doesn't really seem to have any issues?

You can "git repack -a -d" with an old version, or save the multi-pack- index temporarily elsewhere and copy it back after repack, and things work just fine, except of course "git multi-pack-index verify" will complain loudly.

johannes