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From: Sergey Vlasov <vsu@altlinux.ru>
To: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Cc: git@vger.kernel.org, junkio@cox.net
Subject: Re: [PATCH] Add '--create-index' to git-unpack-objects
Date: Wed, 12 Oct 2005 18:55:48 +0400	[thread overview]
Message-ID: <20051012145548.GA2539@master.mivlgu.local> (raw)
In-Reply-To: <Pine.LNX.4.63.0510121612340.6307@wbgn013.biozentrum.uni-wuerzburg.de>

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On Wed, Oct 12, 2005 at 04:25:22PM +0200, Johannes Schindelin wrote:
> On Wed, 12 Oct 2005, Sergey Vlasov wrote:
> > Saving unpacked objects in memory would obviously be unacceptable.
> 
> Actually, this is what git-unpack-objects does. All unresolved deltas are 
> stored in a linked list, and handled later.

Yes, this may be a problem if the pack is large and contains many
deltas.  But these stored deltas are thrown away immediately when the
base object is found; if you want to implement a streaming reindex,
you will need to store them until you reach the end of pack (or write
those objects to some temporary files).

> Of course, it would be nicer to use a seekable file if you have one. But 
> then, I am not at all sure that base objects should be allowed to come 
> later in the file: since the delta chains must not be cyclic, the objects
> can be sorted. Thus, it could be guaranteed that the base objects are 
> already unpacked when unpacking the derived object.

Hmm, pack-objects.c:write_one() does exactly the opposite - it writes
the base object _after_ writing out the delta (but it does not ensure
that ordering completely, so references to base objects can be
pointing in both directions).  Why?

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  reply	other threads:[~2005-10-12 14:56 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-10-12 11:02 [PATCH] Add '--create-index' to git-unpack-objects Johannes Schindelin
2005-10-12 13:34 ` Sergey Vlasov
2005-10-12 13:54   ` [PATCH] Add git-index-pack utility Sergey Vlasov
2005-10-12 14:33     ` Johannes Schindelin
2005-10-12 15:01       ` Sergey Vlasov
2005-10-12 23:57     ` [PATCH] Fix packname hash generation Junio C Hamano
2005-10-13  1:23       ` [PATCH] clone-pack: new option --keep to keep the pack unexploded Junio C Hamano
2005-10-13  2:46       ` [PATCH] Fix packname hash generation Junio C Hamano
2005-10-12 14:25   ` [PATCH] Add '--create-index' to git-unpack-objects Johannes Schindelin
2005-10-12 14:55     ` Sergey Vlasov [this message]
2005-10-12 15:08       ` Johannes Schindelin
2005-10-12 15:20       ` Linus Torvalds

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