Re: git gc --aggressive led to about 40 times slower "git log --raw"

From: Duy Nguyen <pclouds@gmail.com>
Date: Feb 20, 2014, 23:35 UTC
Message-ID: <CACsJy8AeZWPz=39ySQr9MrSUiLyJDQbs02sumS9VjbbGWzP9pw@mail.gmail.com>
In-Reply-To: <xmqqd2ij9be1.fsf@gitster.dls.corp.google.com>

On Thu, Feb 20, 2014 at 1:59 AM, Junio C Hamano <gitster@pobox.com> wrote:

Show 12 quoted lines

> Philippe Vaucher <philippe.vaucher@gmail.com> writes:
>
>>> fwiw this is the thread that added --depth=250
>>>
>>> http://thread.gmane.org/gmane.comp.gcc.devel/94565/focus=94626
>>
>> This post is quite interesting:
>> http://article.gmane.org/gmane.comp.gcc.devel/94637
>
> Yes, it most clearly says that --depth=250 was *not* a
> recommendation, with technical background to explain why such a long
> delta chain is a bad idea.

On the other hand, the size reduction is really nice (320MB vs 500MB). I don't know if we can do this, but does it make sense to apply --depth=250 for old commits only and shallow depth for recent commits?

For old projects, commits older than 1-2 years is probably less often accessed and could use some aggressive packing. This still hits git-blame badly. We could even make sure all objects "on the blame surface" have short delta chain. But that may be pushing pack-objects too much.

-- 
Duy