Received-SPF: pass (sog-mx-3.v43.ch3.sourceforge.com: domain of gmail.com
	designates 209.85.213.170 as permitted sender)
	client-ip=209.85.213.170; envelope-from=laanwj@gmail.com;
	helo=mail-ig0-f170.google.com; 
MIME-Version: 1.0
In-Reply-To: <CANEZrP04O7EqB=TqyTiC7O1K2A9R0nKJ_ssANHKg=Byum8-LtA@mail.gmail.com>
References: <CANEZrP04O7EqB=TqyTiC7O1K2A9R0nKJ_ssANHKg=Byum8-LtA@mail.gmail.com>
Date: Thu, 10 Apr 2014 13:57:00 +0200
Message-ID: <CA+s+GJDbYjwhpsV15a+7kCO_vTstEewVrwvqbnB=a5zOSwFC6Q@mail.gmail.com>
From: Wladimir <laanwj@gmail.com>
To: Mike Hearn <mike@plan99.net>
Content-Type: multipart/alternative; boundary=047d7b10caa93386b404f6aeea51
Cc: Bitcoin Dev <bitcoin-development@lists.sourceforge.net>
Subject: Re: [Bitcoin-development] Chain pruning
Precedence: list

--047d7b10caa93386b404f6aeea51
Content-Type: text/plain; charset=UTF-8

On Thu, Apr 10, 2014 at 1:37 PM, Mike Hearn <mike@plan99.net> wrote:

> Chain pruning is probably a separate thread, changing subject.
>
>
>> Reason is that the actual blocks available are likely to change
>> frequently (if
>> you keep the last week of blocks
>
>
> I doubt anyone would specify blocks to keep in terms of time. More likely
> it'd be in terms of megabytes, as that's the actual resource constraint on
> nodes.
>

Well with bitcoin, (average) time, number of blocks and (maximum) size are
all related to each other so it doesn't matter how it is specified, it's
always possible to give estimates of all three.

As for implementation it indeed makes most sense to work with block ranges.


> Given a block size average it's easy to go from megabytes to num_blocks,
> so I had imagined it'd be a new addr field that specifies how many blocks
> from the chain head are stored. Then you'd connect to some nodes and if
> they indicate their chain head - num_blocks_stored is higher than your
> current chain height, you'd do a getaddr and go looking for nodes that are
> storing far enough back.
>

This assumes that nodes will always be storing the latest blocks. For
dynamic nodes that take part in the consensus this makes sense.

Just wondering: Would there be a use for a [static] node that, say, always
serves only the first 100000 blocks? Or, even, a static range like block
100000 - 200000?

Wladimir

--047d7b10caa93386b404f6aeea51
Content-Type: text/html; charset=UTF-8
Content-Transfer-Encoding: quoted-printable

<div dir=3D"ltr"><div class=3D"gmail_extra"><br><div class=3D"gmail_quote">=
On Thu, Apr 10, 2014 at 1:37 PM, Mike Hearn <span dir=3D"ltr">&lt;<a href=
=3D"mailto:mike@plan99.net" target=3D"_blank">mike@plan99.net</a>&gt;</span=
> wrote:<br>
<blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1p=
x #ccc solid;padding-left:1ex"><div dir=3D"ltr"><div class=3D"gmail_extra">=
<div class=3D"gmail_quote"><div>Chain pruning is probably a separate thread=
, changing subject.</div>
<div>=C2=A0</div><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8=
ex;border-left:1px #ccc solid;padding-left:1ex">
Reason is=C2=A0that the actual blocks available are likely to change freque=
ntly (if<br>
you keep the last week of blocks</blockquote><div><br></div><div>I doubt an=
yone would specify blocks to keep in terms of time. More likely it&#39;d be=
 in terms of megabytes, as that&#39;s the actual resource constraint on nod=
es. </div>
</div></div></div></blockquote><div><br></div><div>Well with bitcoin, (aver=
age) time, number of blocks and (maximum) size are all related to each othe=
r so it doesn&#39;t matter how it is specified, it&#39;s always possible to=
 give estimates of all three.<br>
<br></div><div>As for implementation it indeed makes most sense to work wit=
h block ranges.<br></div><div>=C2=A0</div><blockquote class=3D"gmail_quote"=
 style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><d=
iv dir=3D"ltr">
<div class=3D"gmail_extra"><div class=3D"gmail_quote"><div>Given a block si=
ze average it&#39;s easy to go from megabytes to num_blocks, so I had imagi=
ned it&#39;d be a new addr field that specifies how many blocks from the ch=
ain head are stored. Then you&#39;d connect to some nodes and if they indic=
ate their chain head - num_blocks_stored is higher than your current chain =
height, you&#39;d do a getaddr and go looking for nodes that are storing fa=
r enough back.</div>
</div></div></div></blockquote><div><br></div><div>This assumes that nodes =
will always be storing the latest blocks. For dynamic nodes that take part =
in the consensus this makes sense.<br><br></div><div>Just wondering: Would =
there be a use for a [static] node that, say, always serves only the first =
100000 blocks? Or, even, a static range like block 100000 - 200000?<br>
</div><div><br>Wladimir<br></div></div><br></div></div>

--047d7b10caa93386b404f6aeea51--