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The "--stdin-packs" option can be used to merge objects from multiple
packfiles given via stdin into a new packfile. One big upside of this
option is that we don't have to perform a complete rev walk to enumerate
objects. Instead, we can simply enumerate all objects that are part of
the specified packfiles, which can be significantly faster in very large
repositories.
There is one downside though: when we don't perform a rev walk we also
don't have a good way to learn about the respective object's names. As a
consequence, we cannot use the name hashes as a heuristic to get better
delta selection.
We try to offset this downside though by performing a localized rev
walk: we queue all objects that we're about to repack as interesting,
and all objects from excluded packfiles as uninteresting. We then
perform a best-effort rev walk that allows us to fill in object names.
There is one gotcha here though: when "--exclude-promisor-objects" has
not been given we will perform backfill fetches for any promised objects
that are missing. This used to not be an issue though as this option was
mutually exclusive with "--stdin-packs". But that has changed recently,
and starting with dcc9c7ef47 (builtin/repack: handle promisor packs with
geometric repacking, 2026-01-05) we will now repack promisor packs
during geometric compaction. The consequence is that a geometric repack
may now perform a bunch of backfill fetches.
We of course cannot pass "--exclude-promisor-objects" to fix this
issue -- after all, the whole intent is to repack objects part of a
promisor pack. But arguably we don't have to: the rev walk is intended
as best effort, and we already configure it to ignore missing links to
other objects. So we can adapt the walk to unconditionally disable
fetching any missing objects.
Do so and add a test that verifies we don't backfill any objects.
Reported-by: Lukas Wanko <lwanko@gitlab.com>
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Git - fast, scalable, distributed revision control system
Git is a fast, scalable, distributed revision control system with an unusually rich command set that provides both high-level operations and full access to internals.
Git is an Open Source project covered by the GNU General Public License version 2 (some parts of it are under different licenses, compatible with the GPLv2). It was originally written by Linus Torvalds with help of a group of hackers around the net.
Please read the file INSTALL for installation instructions.
Many Git online resources are accessible from https://git-scm.com/ including full documentation and Git related tools.
See Documentation/gittutorial.adoc to get started, then see
Documentation/giteveryday.adoc for a useful minimum set of commands, and
Documentation/git-<commandname>.adoc for documentation of each command.
If git has been correctly installed, then the tutorial can also be
read with man gittutorial or git help tutorial, and the
documentation of each command with man git-<commandname> or git help <commandname>.
CVS users may also want to read Documentation/gitcvs-migration.adoc
(man gitcvs-migration or git help cvs-migration if git is
installed).
The user discussion and development of Git take place on the Git mailing list -- everyone is welcome to post bug reports, feature requests, comments and patches to git@vger.kernel.org (read Documentation/SubmittingPatches for instructions on patch submission and Documentation/CodingGuidelines).
Those wishing to help with error message, usage and informational message
string translations (localization l10) should see po/README.md
(a po file is a Portable Object file that holds the translations).
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Issues which are security relevant should be disclosed privately to the Git Security mailing list git-security@googlegroups.com.
The maintainer frequently sends the "What's cooking" reports that list the current status of various development topics to the mailing list. The discussion following them give a good reference for project status, development direction and remaining tasks.
The name "git" was given by Linus Torvalds when he wrote the very first version. He described the tool as "the stupid content tracker" and the name as (depending on your mood):
- random three-letter combination that is pronounceable, and not actually used by any common UNIX command. The fact that it is a mispronunciation of "get" may or may not be relevant.
- stupid. contemptible and despicable. simple. Take your pick from the dictionary of slang.
- "global information tracker": you're in a good mood, and it actually works for you. Angels sing, and a light suddenly fills the room.
- "goddamn idiotic truckload of sh*t": when it breaks