From: David Lang <dlang@digitalinsight.com>
To: Jon Smirl <jonsmirl@gmail.com>
Cc: Johannes Schindelin <Johannes.Schindelin@gmx.de>,
git <git@vger.kernel.org>
Subject: Re: Compression and dictionaries
Date: Mon, 14 Aug 2006 09:32:50 -0700 (PDT) [thread overview]
Message-ID: <Pine.LNX.4.63.0608140930380.14796@qynat.qvtvafvgr.pbz> (raw)
In-Reply-To: <9e4733910608140915i728004c1p216bf3d74fcc6ab7@mail.gmail.com>
On Mon, 14 Aug 2006, Jon Smirl wrote:
> On 8/14/06, Johannes Schindelin <Johannes.Schindelin@gmx.de> wrote:
>> I still think that this is important to think through: Is it worth a
>> couple of kilobytes (I doubt that it would be as much as 1MB in _total_),
>> and be on the unsafe side?
>
> The only "unsafe" aspect I see to this is if the global dictionary
> doesn't contain any of the words in the documents being encoded. In
> that case the global dictionary will occupy the short huffman keys
> forcing longer internal keys. The keys for the words in the document
> would be longer by a about a bit on average.
the other factor that was mentioned was that a single-bit corruption in the
dictionary would make the entire pack file useless. if this is really a concern
then just store multiple copies of the dictionary. on a pack with lots of files
in it it can still be a significant win.
David Lang
next prev parent reply other threads:[~2006-08-14 16:34 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-08-14 3:37 Compression and dictionaries Jon Smirl
2006-08-14 3:56 ` Shawn Pearce
2006-08-14 4:07 ` Jon Smirl
2006-08-14 4:17 ` Shawn Pearce
2006-08-14 7:48 ` Alex Riesen
2006-08-14 10:06 ` Erik Mouw
2006-08-14 12:33 ` Johannes Schindelin
2006-08-14 14:08 ` Jon Smirl
2006-08-14 14:45 ` Johannes Schindelin
2006-08-14 16:15 ` Jon Smirl
2006-08-14 16:32 ` David Lang [this message]
2006-08-14 16:55 ` Jakub Narebski
2006-08-14 17:15 ` Jeff Garzik
2006-08-14 17:34 ` David Lang
2006-08-14 17:50 ` Jeff Garzik
2006-08-14 18:48 ` Jon Smirl
2006-08-14 19:08 ` David Lang
2006-08-14 19:38 ` Johannes Schindelin
2006-08-14 15:14 ` Alex Riesen
2006-08-14 15:26 ` Johannes Schindelin
-- strict thread matches above, loose matches on Subject: below --
2006-08-15 8:33 linux
2006-08-15 13:29 ` Jon Smirl
2006-08-15 14:55 ` Jon Smirl
2006-08-16 0:37 ` linux
[not found] ` <4b73d43f0608152243i15b37036x7aa50aa3afc2b02f@mail.gmail.com>
2006-08-16 5:50 ` Jon Smirl
2006-08-16 6:33 ` Johannes Schindelin
2006-08-16 6:55 ` Shawn Pearce
2006-08-16 7:09 ` Johannes Schindelin
2006-08-16 14:43 ` Jon Smirl
2006-08-17 22:33 ` linux
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