From: Taylor Blau <me@ttaylorr.com>
To: Derrick Stolee <stolee@gmail.com>
Cc: Johannes Berg <johannes@sipsolutions.net>,
git@vger.kernel.org, bup-list@googlegroups.com
Subject: Re: [RFC PATCH] multi-pack-index: allow operating without pack files
Date: Mon, 23 Aug 2021 00:05:50 -0400 [thread overview]
Message-ID: <YSMenndGYr14okwv@nand.local> (raw)
In-Reply-To: <edb9c412-70c8-4fc6-04ab-417eca05ee15@gmail.com>
On Sun, Aug 22, 2021 at 08:34:43PM -0400, 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.
>
> I understand your goal to relax a condition of the multi-pack-index
> file, but it's triggered by a flag during write and that choice
> isn't persisted into the file. There is no way for a later Git
> process to understand that the multi-pack-index doesn't actually
> guarantee object existence.
We're going to run into problems much earlier than that, though: the
MIDX needs to load information about objects from packs in order to
break ties when multiple copies of the same object exist in multiple
packs (according to that pack's mtime).
So I'm not sure how we would even write a MIDX without physical packs on
disk that we can open and stat, let along how we would teach Git to
handle a situation where packs that did exist when writing a MIDX went
away when we tried to read from the same MIDX later on.
Thanks,
Taylor
next prev parent reply other threads:[~2021-08-23 4:05 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-20 19:55 [RFC PATCH] multi-pack-index: allow operating without pack files Johannes Berg
2021-08-23 0:34 ` Derrick Stolee
2021-08-23 1:11 ` Martin Fick
2021-08-23 8:21 ` Johannes Berg
2021-08-23 4:05 ` Taylor Blau [this message]
2021-08-23 8:23 ` Johannes Berg
2021-08-23 9:22 ` Johannes Berg
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