git@vger.kernel.org mailing list mirror (one of many)
 help / color / mirror / code / Atom feed
From: Junio C Hamano <gitster@pobox.com>
To: Patrick Steinhardt <ps@pks.im>
Cc: Christian Couder <christian.couder@gmail.com>,
	git@vger.kernel.org, John Cai <johncai86@gmail.com>,
	Jonathan Tan <jonathantanmy@google.com>,
	Jonathan Nieder <jrnieder@gmail.com>,
	Taylor Blau <me@ttaylorr.com>, Derrick Stolee <stolee@gmail.com>,
	Christian Couder <chriscool@tuxfamily.org>
Subject: Re: [PATCH v4 2/3] repack: add --filter=<filter-spec> option
Date: Thu, 05 Jan 2023 10:39:20 +0900	[thread overview]
Message-ID: <xmqqa62xu5dj.fsf@gitster.g> (raw)
In-Reply-To: <Y7WTuQvoHEWRlEA4@ncase> (Patrick Steinhardt's message of "Wed, 4 Jan 2023 15:56:57 +0100")

Patrick Steinhardt <ps@pks.im> writes:

> While this is a nice safeguard, I wonder whether it is sufficient.
> Suppose you for example have a non-bare repository that already has
> blobs checked out that would become removed by the filtering repack --
> does Git handle this situation gracefully?
>
> A quick check seems to indicate that it does. But not quite as well as
> I'd have hoped: when I switch to a detached HEAD with an arbitrary
> commit and then execute `git repack --filter=blob:none` then it also
> removes blobs that are referenced by the currently checked-out commit.
> This may or may not be what the user is asking for, but I'd rather lean
> towards this behaviour being surprising.

Hmph, the user asked not to have blobs that came from remote locally
and instead refetch them from the promisor on-demand, so I would
expect some pruning to happen (I am not a lazy-clone user, though).

As long as we do the pruning sensibly, that is.

Unless you are always following somebody else without doing any work
on your own, you are likely to have objects that exist only locally
and nowhere else.  It would be unexpected and surprising, if we lost
them only because they are of type 'blob' and because there is a
promisor remote configured.

Even if that is documented, that would be an unacceptable foot-gun
misfeature.  It is not just a local repository corruption that can
be recovered by cloning from elsewhere.  We are looking at lost
work that cannot be recovered.

I wonder if this topic can be salvaged by making it less aggressive
in pruning, perhaps by traversing from the tips of remote-tracking
branches of the promisor remote to identify which blobs can safely
be pruned (by definition, promisor remote cannot lose objects that
it once published, or its cloners will immediately have corrupt
repositories).  That may turn this from a misfeature into a feature.

Thanks.

  reply	other threads:[~2023-01-05  1:39 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-10-12 13:51 [PATCH 0/3] Implement filtering repacks Christian Couder
2022-10-12 13:51 ` [PATCH 1/3] pack-objects: allow --filter without --stdout Christian Couder
2022-10-12 13:51 ` [PATCH 2/3] repack: add --filter=<filter-spec> option Christian Couder
2022-10-12 13:51 ` [PATCH 3/3] repack: introduce --force to force filtering Christian Couder
2022-10-14 16:46 ` [PATCH 0/3] Implement filtering repacks Junio C Hamano
2022-10-20 11:23   ` Christian Couder
2022-10-28 19:49     ` Taylor Blau
2022-10-28 20:26       ` Junio C Hamano
2022-11-07  9:12         ` Christian Couder
2022-11-07  9:00       ` Christian Couder
2022-10-25 12:28 ` [PATCH v2 0/2] " Christian Couder
2022-10-25 12:28   ` [PATCH v2 1/2] pack-objects: allow --filter without --stdout Christian Couder
2022-10-25 12:28   ` [PATCH v2 2/2] repack: add --filter=<filter-spec> option Christian Couder
2022-10-28 19:54   ` [PATCH v2 0/2] Implement filtering repacks Taylor Blau
2022-11-07  9:29     ` Christian Couder
2022-11-22 17:51   ` [PATCH v3 " Christian Couder
2022-11-22 17:51     ` [PATCH v3 1/2] pack-objects: allow --filter without --stdout Christian Couder
2022-11-22 17:51     ` [PATCH v3 2/2] repack: add --filter=<filter-spec> option Christian Couder
2022-11-23  0:31     ` [PATCH v3 0/2] Implement filtering repacks Junio C Hamano
2022-12-21  3:53       ` Christian Couder
2022-11-23  0:35     ` Junio C Hamano
2022-12-21  4:04     ` [PATCH v4 0/3] " Christian Couder
2022-12-21  4:04       ` [PATCH v4 1/3] pack-objects: allow --filter without --stdout Christian Couder
2023-01-04 14:56         ` Patrick Steinhardt
2022-12-21  4:04       ` [PATCH v4 2/3] repack: add --filter=<filter-spec> option Christian Couder
2023-01-04 14:56         ` Patrick Steinhardt
2023-01-05  1:39           ` Junio C Hamano [this message]
2022-12-21  4:04       ` [PATCH v4 3/3] gc: add gc.repackFilter config option Christian Couder
2023-01-04 14:57         ` Patrick Steinhardt
2024-05-15 13:25 ` [PATCH v2 0/3] upload-pack: support a missing-action Christian Couder
2024-05-15 13:25   ` [PATCH v2 1/3] rev-list: refactor --missing=<missing-action> Christian Couder
2024-05-15 16:16     ` Junio C Hamano
2024-05-15 13:25   ` [PATCH v2 2/3] pack-objects: use the missing action API Christian Couder
2024-05-15 16:46     ` Junio C Hamano
2024-05-15 13:25   ` [PATCH v2 3/3] upload-pack: allow configuring a missing-action Christian Couder
2024-05-15 17:08     ` Junio C Hamano
2024-05-15 13:59   ` [PATCH v2 0/3] upload-pack: support " Christian Couder

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

  List information: http://vger.kernel.org/majordomo-info.html

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=xmqqa62xu5dj.fsf@gitster.g \
    --to=gitster@pobox.com \
    --cc=chriscool@tuxfamily.org \
    --cc=christian.couder@gmail.com \
    --cc=git@vger.kernel.org \
    --cc=johncai86@gmail.com \
    --cc=jonathantanmy@google.com \
    --cc=jrnieder@gmail.com \
    --cc=me@ttaylorr.com \
    --cc=ps@pks.im \
    --cc=stolee@gmail.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
Code repositories for project(s) associated with this public inbox

	https://80x24.org/mirrors/git.git

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).