From: Liu Yubao <yubao.liu@gmail.com>
To: Junio C Hamano <gitster@pobox.com>
Cc: git list <git@vger.kernel.org>
Subject: Re: two questions about the format of loose object
Date: Mon, 01 Dec 2008 17:28:53 +0800 [thread overview]
Message-ID: <4933AE55.2090007@gmail.com> (raw)
In-Reply-To: <7voczws3np.fsf@gitster.siamese.dyndns.org>
Junio C Hamano wrote:
> Liu Yubao <yubao.liu@gmail.com> writes:
>
>
> A hint for understanding why loose objects are compressed is that
> packfiles were invented much later in the history of git.
>
> These are both good questions, and it might have made a difference if they
> were posed in early April 2005.
>
> At this point, the plain and clear answer to both of these "Why not"
> questions is "because that is the way it is and it is costly to change
> them now in thousands of repositories people use every day."
>
> In other words, it is not interesting anymore to raise these questions
> now, especially as a suggestion to change the system, unless they are
> accompanied by arguments that convinces everybody that the cost of such a
> change outweighs the benefits, and a clear transition plans how to upgrade
> everybody's existing repositories without any pain.
>
Thanks for your explanation, but I doubt if it's too costly to change the
format of loose object, after all this doesn't change the format of pack
file and affect git-pull/fetch of old git client.
I ask the "why not" questions because I doubt if I miss some technical points
that the change isn't worth at all in fact.
If no severe technical problem will occur, I think it's worth breaking
*forward* compatibility for better performance and I'm willing to implement
it.
Some cons and pros.
cons:
* old git client can't read loose objects in new format
(People degrade git rarely and old git can read pack files
generated by new git, so it's not a big problem)
pros:
* avoid compressing and uncompressing loose objects that are likely
frequently used when you are coding/merging
* share loose objects among multipe git processes
* the new code path is simpler although we will have more code paths for
compatibility
Best regards,
Liu Yubao
next prev parent reply other threads:[~2008-12-01 9:30 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-12-01 8:00 two questions about the format of loose object Liu Yubao
2008-12-01 8:25 ` Junio C Hamano
2008-12-01 9:28 ` Liu Yubao [this message]
2008-12-01 11:32 ` Jakub Narebski
2008-12-02 2:19 ` Liu Yubao
2008-12-01 15:21 ` Shawn O. Pearce
2008-12-02 2:43 ` Liu Yubao
2008-12-02 1:48 ` [PATCH 0/5] support reading and writing uncompressed " Liu Yubao
2008-12-02 1:51 ` [PATCH 1/5] avoid parse_sha1_header() accessing memory out of bound Liu Yubao
2008-12-02 15:42 ` Shawn O. Pearce
2008-12-03 3:49 ` Liu Yubao
2008-12-02 1:53 ` [PATCH 2/5] don't die immediately when convert an invalid type name Liu Yubao
2008-12-02 1:55 ` [PATCH 3/5] optimize parse_sha1_header() a little by detecting object type Liu Yubao
2008-12-02 15:53 ` Shawn O. Pearce
2008-12-03 4:06 ` Liu Yubao
2008-12-02 1:56 ` [PATCH 4/5] support reading uncompressed loose object Liu Yubao
2008-12-02 15:58 ` Shawn O. Pearce
2008-12-03 4:09 ` Liu Yubao
2008-12-02 2:03 ` [PATCH 5/5] support writing " Liu Yubao
2008-12-02 16:07 ` Shawn O. Pearce
2008-12-03 4:22 ` Liu Yubao
2008-12-02 3:11 ` [PATCH 0/5] support reading and " Liu Yubao
2008-12-01 12:16 ` two questions about the format of " Nick Andrew
2008-12-02 2:26 ` Liu Yubao
2008-12-01 15:32 ` Shawn O. Pearce
2008-12-02 3:05 ` Liu Yubao
2008-12-04 0:54 ` Nicolas Pitre
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=4933AE55.2090007@gmail.com \
--to=yubao.liu@gmail.com \
--cc=git@vger.kernel.org \
--cc=gitster@pobox.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).