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From: Jakub Narebski <jnareb@gmail.com>
To: Brandon Williams <bmwill@google.com>
Cc: Jeff Hostetler <git@jeffhostetler.com>,
	Ævar Arnfjörð Bjarmason  <avarab@gmail.com>,
	Alex Vandiver <alexmv@dropbox.com>,
	git@vger.kernel.org, jonathantanmy@google.com, stolee@gmail.com,
	sbeller@google.com, peff@peff.net, johannes.schindelin@gmx.de,
	Jonathan Nieder <jrnieder@gmail.com>,
	Michael Haggerty <mhagger@alum.mit.edu>
Subject: Re: Git Merge contributor summit notes
Date: Sat, 07 Apr 2018 22:37:37 +0200
Message-ID: <86tvsmeory.fsf@gmail.com> (raw)
In-Reply-To: <20180326180517.GA205538@google.com>

Brandon Williams <bmwill@google.com> writes:
> On 03/26, Jeff Hostetler wrote:

[...]
>> All of these cases could be eliminated if the type/size were available
>> in the OID.
>> 
>> Just a thought.  While we are converting to a new hash it seems like
>> this would be a good time to at least discuss it.
>
> Echoing what Stefan said.  I don't think its a good idea to embed this
> sort of data into the OID.  There are a lot of reasons but one of them
> being that would block having access to this data behind completing the
> hash transition (which could very well still be years away from
> completing).
>
> I think that a much better approach would be to create a meta-data data
> structure, much like the commit graph that stolee has been working on)
> which can store this data along side the objects (but not in the
> packfiles themselves).  It could be a stacking structure which is
> periodically coalesced and we could add in a wire feature to fetch this
> meta data from the server upon fetching objects.

Well, the type of the object is available, from what I remember, in the
bitmap file for a packfile (if one does enable creaating them).  There
are four compressed bit vectors, one for each type, with bit set to 1 on
i-th place if i-th object in packfile is of given type.

Just FYI.
--
Jakub Narębski

  reply index

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-10  0:06 Alex Vandiver
2018-03-10 13:01 ` Ævar Arnfjörð Bjarmason
2018-03-11  0:02   ` Junio C Hamano
2018-03-12 23:40   ` Jeff King
2018-03-13  0:49     ` Brandon Williams
2018-03-12 23:33 ` Jeff King
2018-03-25 22:58 ` Ævar Arnfjörð Bjarmason
2018-03-26 17:33   ` Jeff Hostetler
2018-03-26 17:56     ` Stefan Beller
2018-03-26 18:54       ` Jeff Hostetler
2018-03-26 18:05     ` Brandon Williams
2018-04-07 20:37       ` Jakub Narebski [this message]
2018-03-26 21:00     ` Including object type and size in object id (Re: Git Merge contributor summit notes) Jonathan Nieder
2018-03-26 21:42       ` Jeff Hostetler
2018-03-26 22:40       ` Junio C Hamano
2018-03-26 20:54   ` Per-object encryption " Jonathan Nieder
2018-03-26 21:22     ` Ævar Arnfjörð Bjarmason

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