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From: Shawn Pearce <spearce@spearce.org>
To: Dave Borowitz <dborowitz@google.com>
Cc: git <git@vger.kernel.org>, Jeff King <peff@peff.net>,
	Michael Haggerty <mhagger@alum.mit.edu>,
	Junio C Hamano <gitster@pobox.com>
Subject: Re: reftable [v4]: new ref storage format
Date: Tue, 1 Aug 2017 08:27:26 -0700	[thread overview]
Message-ID: <CAJo=hJvsBTDO-8OxrxwfV-=4XWW1w-616DGu31aVb5EU7DWcDA@mail.gmail.com> (raw)
In-Reply-To: <CAD0k6qTFV2AAbWiKvi4=OoodoXEgxswLEbraC3xP1LzvtRRaGg@mail.gmail.com>

On Tue, Aug 1, 2017 at 6:54 AM, Dave Borowitz <dborowitz@google.com> wrote:
> On Sun, Jul 30, 2017 at 11:51 PM, Shawn Pearce <spearce@spearce.org> wrote:
>> - Ref-like files (FETCH_HEAD, MERGE_HEAD) also use type 0x3.
>
>> - Combine reflog storage with ref storage for small transactions.
>> - Separate reflog storage for base refs and historical logs.
>
> How is the stash implemented in reftable? In particular, "git stash
> drop" needs to be able to remove an arbitrary single entry from a
> reflog.
>
> I don't think the current proposal supports writing tombstones for
> reflog entries, so this maybe implies that "stash drop" would have to
> be implemented by rewriting the whole reflog for the stash ref during
> compaction. Can the current compaction algorithm support this?

Yes, the reftable holding the stash would have to be completely
rewritten for a "stash drop" command to be able to remove a reflog
entry.

> I suppose there are more exotic alternatives:
> * Go back to the normal ref(log) format for refs/stash. I figure you
> probably don't want to do this, given that you already moved other
> ref-like files into the reftable in a later revision of this proposal.
> * Implement the whole stash storage/command in some other way that
> doesn't depend on reflog.

I think the simplest is just put refs/stash in its own reftable, and
put that reftable in the stack somewhere. Editing refs/stash reflog
requires rewriting and replacing that reftable in the stack, but
otherwise doesn't impact any other (possibly much larger) reflog.

Pushing things onto refs/stash would be creating new small transaction
reftables on the top of the stack, which should be compacted with the
lower refs/stash table. I guess that means refs/stash needs special
handling in some of the compaction code to keep it isolated.

  reply	other threads:[~2017-08-01 15:27 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-07-31  3:51 Shawn Pearce
2017-07-31 17:41 ` Dave Borowitz
2017-07-31 19:01 ` Stefan Beller
2017-07-31 23:05   ` Shawn Pearce
2017-07-31 19:42 ` Junio C Hamano
2017-07-31 23:43   ` Shawn Pearce
2017-08-01 16:08     ` Shawn Pearce
2017-08-01  6:41 ` Michael Haggerty
2017-08-01 20:23   ` Shawn Pearce
2017-08-02  0:49     ` Michael Haggerty
2017-08-01 23:27   ` Shawn Pearce
2017-08-01 23:54     ` Shawn Pearce
2017-08-02  1:51     ` Michael Haggerty
2017-08-02  2:38       ` Shawn Pearce
2017-08-02  9:28         ` Jeff King
2017-08-02 15:17           ` Shawn Pearce
2017-08-02 16:51             ` Junio C Hamano
2017-08-02 17:28             ` Jeff King
2017-08-02 12:20         ` Dave Borowitz
2017-08-02 17:18           ` Jeff King
2017-08-03 18:38         ` Michael Haggerty
2017-08-03 22:26           ` Shawn Pearce
2017-08-03 22:48             ` Michael Haggerty
2017-08-04  2:50               ` Shawn Pearce
2017-08-05 21:00       ` Shawn Pearce
2017-08-01 13:54 ` Dave Borowitz
2017-08-01 15:27   ` Shawn Pearce [this message]
2017-08-02 19:50 ` Junio C Hamano
2017-08-02 20:28   ` Jeff King
2017-08-03 22:17     ` Shawn Pearce
2017-08-03  1:50   ` Junio C Hamano
2017-08-03  2:21     ` Shawn Pearce
2017-08-03  2:36       ` Junio C Hamano
2017-08-02 19:54 ` Stefan Beller

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