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From: "Ævar Arnfjörð Bjarmason" <>
To: Junio C Hamano <>
Cc: "Derrick Stolee" <>,
	"Git List" <>, "Jeff King" <>,
	"Jakub Narębski" <>,
	"Derrick Stolee" <>
Subject: Re: [RFC] Generation Number v2
Date: Wed, 31 Oct 2018 13:54:48 +0100	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On Tue, Oct 30 2018, Junio C Hamano wrote:

> Derrick Stolee <> writes:
>> In contrast, maximum generation numbers and corrected commit
>> dates both performed quite well. They are frequently the top
>> two performing indexes, and rarely significantly different.
>> The trade-off here now seems to be: which _property_ is more important,
>> locally-computable or backwards-compatible?
> Nice summary.
> As I already said, I personally do not think being compatible with
> currently deployed clients is important at all (primarily because I
> still consider the whole thing experimental), and there is a clear
> way forward once we correct the mistake of not having a version
> number in the file format that tells the updated clients to ignore
> the generation numbers.  For longer term viability, we should pick
> something that is immutable, reproducible, computable with minimum
> input---all of which would lead to being incrementally computable, I
> would think.

I think it depends on what we mean by backwards compatibility. None of
our docs are saying this is experimental right now, just that it's
opt-in like so many other git-config(1) options.

So if we mean breaking backwards compatibility in that we'll write a new
file or clobber the existing one with a version older clients can't use
as an optimization, fine.

But it would be bad to produce a hard error on older clients, but
avoiding that seems as easy as just creating a "commit-graph2" file in

  parent reply	other threads:[~2018-10-31 12:54 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-29 16:55 [RFC] Generation Number v2 Derrick Stolee
2018-10-29 19:22 ` Stefan Beller
2018-10-29 20:06   ` Derrick Stolee
2018-11-01 20:06   ` Jakub Narebski
2018-11-02  9:30     ` Jakub Narebski
2018-11-03 17:27       ` Jakub Narebski
2018-10-29 20:25 ` Derrick Stolee
2018-11-01 22:13   ` Jakub Narebski
2018-10-30  3:59 ` Junio C Hamano
2018-10-31 12:30   ` Derrick Stolee
2018-11-02 13:33     ` Jakub Narebski
2018-10-31 12:54   ` Ævar Arnfjörð Bjarmason [this message]
2018-10-31 13:04     ` Derrick Stolee
2018-11-02 17:44       ` Jakub Narebski
2018-11-01 12:27 ` Jakub Narebski
2018-11-01 13:29   ` Derrick Stolee
2018-11-03 12:33     ` Jakub Narebski

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