From: Stefan Beller <sbeller@google.com>
To: Shawn Pearce <spearce@spearce.org>
Cc: git <git@vger.kernel.org>,
Michael Haggerty <mhagger@alum.mit.edu>,
Junio C Hamano <gitster@pobox.com>,
David Borowitz <dborowitz@google.com>, Jeff King <peff@peff.net>
Subject: Re: reftable [v7]: new ref storage format
Date: Tue, 15 Aug 2017 23:15:45 -0700 [thread overview]
Message-ID: <CAGZ79kZ4m0-KBFs1pbOvRqkR=0vn-Jbn1FATL_KzW+km0K-S2A@mail.gmail.com> (raw)
In-Reply-To: <CAJo=hJsZcAM9sipdVr7TMD-FD2V2W6_pvMQ791EGCDsDkQ033w@mail.gmail.com>
On Tue, Aug 15, 2017 at 7:48 PM, Shawn Pearce <spearce@spearce.org> wrote:
> 7th iteration of the reftable storage format.
>
> You can read a rendered version of this here:
> https://googlers.googlesource.com/sop/jgit/+/reftable/Documentation/technical/reftable.md
>
> Changes from v6:
> - Blocks are variable sized, and alignment is optional.
> - ref index is required on variable sized multi-block files.
>
> - restart_count/offsets are again at the end of the block.
> - value_type = 0x3 is only for symbolic references.
> - "other" files cannot be stored in reftable.
>
> - object blocks are explicitly optional.
> - object blocks use position (offset in bytes), not block id.
> - removed complex log_chained format for log blocks
>
> - Layout uses log, ref file extensions
> - Described reader algorithm to obtain a snapshot
- back to the old "intra-block index is last"
for all block types. ok.
- changed (only ref?) indexes to start char + 3 byte size:
Which starting char do object/log indexes have?
"Unaligned files must include the ref index to support fast lookup."
Why this? I would imagine the client (which has ~5 branches),
would not need this, but only a ref block, that's it.
Ctrl-F for 'block_size' reveals nothing is computed
relative to the block_size in this format, yet we can
set it to an arbitrary number. If following the spec,
the reader at $DAY_JOB needs to be able to read
both aligned and unaligned reftables, despite our plan
to ever write aligned ref tables, what would the reader
use the block_size for? (I think we can omit that field
from the header/footer now, no?)
next prev parent reply other threads:[~2017-08-16 6:15 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-16 2:48 reftable [v7]: new ref storage format Shawn Pearce
2017-08-16 6:15 ` Stefan Beller [this message]
2017-08-16 15:54 ` Shawn Pearce
2017-08-16 21:05 ` Junio C Hamano
2017-08-17 8:06 ` Michael Haggerty
2017-08-17 18:22 ` Junio C Hamano
2017-08-18 0:52 ` Shawn Pearce
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