From: Shawn Pearce <spearce@spearce.org>
To: Dave Borowitz <dborowitz@google.com>
Cc: Michael Haggerty <mhagger@alum.mit.edu>, git <git@vger.kernel.org>
Subject: Re: reftable: new ref storage format
Date: Sun, 16 Jul 2017 14:31:20 -0700 [thread overview]
Message-ID: <CAJo=hJue2MYcE-xc9qjRXfMCf5f5+QPzmZQwHtqgr_zALeQziA@mail.gmail.com> (raw)
In-Reply-To: <CAD0k6qSpNTWkn-97nQQ1DJrh=sd3dppTXytfbafqj-eVsWDTFg@mail.gmail.com>
On Sun, Jul 16, 2017 at 2:13 PM, Dave Borowitz <dborowitz@google.com> wrote:
> On Sun, Jul 16, 2017 at 3:43 PM, Shawn Pearce <spearce@spearce.org> wrote:
>> True... but... in my "android" example repository we have 866,456 live
>> refs. A block size of 64k needs only 443 blocks, and a 12k index, to
>> get the file to compress to 28M (vs. 62M packed-refs).
>>
>> Index records are averaging 28 bytes per block. That gives us room for
>> about 1955 blocks, or 4,574,700 refs before the index block exceeds
>> 64k.
>
> That's only a 5x increase over the current number of refs in this
> android repo. I would not be so sure this repo doesn't grow another 5x
> in the next few years. Especially as the other optimizations for
> working with large repos start to be applied, so it won't be
> prohibitively painful to work with such a repo.
>
> Are we ok with increasing the block size when this eventually happens?
> (At least I think that's what we would have to do, I haven't been
> following closely the discussion on scaling limits.)
I think I'd try letting the index grow to 4 blocks (256k) before I
considered increasing the block size. Remember pack idx files are much
larger, and are loaded wholesale into memory by JGit. A ref idx at
256k might not be problematic.
next prev parent reply other threads:[~2017-07-16 21:31 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-13 0:17 reftable: new ref storage format Shawn Pearce
2017-07-13 19:32 ` Jeff King
2017-07-13 19:56 ` Stefan Beller
2017-07-13 20:35 ` Jeff King
2017-07-13 21:51 ` Eric Wong
2017-07-14 0:27 ` Shawn Pearce
2017-07-14 20:10 ` Jeff King
2017-07-14 0:11 ` Shawn Pearce
2017-07-14 14:27 ` Dave Borowitz
2017-07-14 15:31 ` Shawn Pearce
2017-07-14 20:08 ` Jeff King
2017-07-16 6:01 ` Shawn Pearce
2017-07-16 10:01 ` Jeff King
2017-07-16 8:07 ` Johannes Sixt
2017-07-16 10:03 ` Jeff King
2017-07-16 10:10 ` Johannes Sixt
2017-07-16 17:33 ` Michael Haggerty
2017-07-16 19:43 ` Shawn Pearce
2017-07-16 21:12 ` Shawn Pearce
2017-07-16 21:13 ` Dave Borowitz
2017-07-16 21:31 ` Shawn Pearce [this message]
2017-07-18 1:43 ` Michael Haggerty
2017-07-18 18:53 ` Junio C Hamano
2017-07-23 22:56 ` Shawn Pearce
2017-07-23 23:03 ` Shawn Pearce
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