Content-Type: text/plain; charset=utf-8
Mime-Version: 1.0 (Mac OS X Mail 8.2 \(2104\))
From: Peter R <peter_r@gmx.com>
In-Reply-To: <CAAS2fgTLE1cpDqKTiy0r1VMex7zTAB8tgUC=Y0WXmbNBJL42xQ@mail.gmail.com>
Date: Sat, 14 Nov 2015 17:45:03 -0800
Content-Transfer-Encoding: quoted-printable
Message-Id: <6DAD1D38-A156-4507-B506-BF66F26E6594@gmx.com>
References: <5631C363.5060705@neomailbox.net>
	<201510290803.52734.luke@dashjr.org>
	<5632DE33.7030600@bitcartel.com>
	<CAAS2fgTga_vTfOKrFu_hEzXSfTfg9FRfJ6aL6ginuGFqnbm7=w@mail.gmail.com>
	<3CB90C47-293E-4C18-A381-E5203483D68F@gmx.com>
	<CAAS2fgRdK4bDr3x_y9UpdH234PQSfD7U539HBLA==+hLQJ_7Fw@mail.gmail.com>
	<571D9B7F-077D-4B80-B577-1C18FF2ECF31@gmx.com>
	<CAAS2fgTLE1cpDqKTiy0r1VMex7zTAB8tgUC=Y0WXmbNBJL42xQ@mail.gmail.com>
To: Gregory Maxwell <gmaxwell@gmail.com>
Sender: Peter_R@gmx.com
Cc: Bitcoin Dev <bitcoin-dev@lists.linuxfoundation.org>,
	telemaco <telemaco@neomailbox.net>
Subject: Re: [bitcoin-dev] [patch] Switching Bitcoin Core to sqlite db
Precedence: list


> On Nov 14, 2015, at 5:08 PM, Gregory Maxwell <gmaxwell@gmail.com> =
wrote:
>=20
> On Sun, Nov 15, 2015 at 1:02 AM, Peter R <peter_r@gmx.com> wrote:
>> Hi Greg,
>>=20
>> Like you said, the issue with using more than one database technology =
is not that one node would prove that Block X is valid while the another =
node proves that Block X is NOT valid.  Instead, the problem is that one =
node might say =E2=80=9Cvalid=E2=80=9D while the other node says =E2=80=9C=
I don=E2=80=99t know.=E2=80=9D
>=20
> Sometimes errors are such that you can catch them (if you're super
> vigilant and know an error is even possible in that case)-- and
> indeed, in that case you can get a "I don't know, something is
> wrong.", other times errors are undetectable.

Agreed.  There are two cases to consider:

Type 1.  One implementation says =E2=80=9Cyes=E2=80=9D or =E2=80=9Cno,=E2=80=
=9D while the other says =E2=80=9CI don=E2=80=99t know=E2=80=9D, and

Type 2.  One implementation says =E2=80=9Cyes=E2=80=9D and the other =
says =E2=80=9Cno,=E2=80=9D because of a bug. =20

My previous email described how Type 1 consensus failures can be safely =
dealt with.  These include many kinds of database exceptions (e.g., the =
LevelDB fork at block #225,430), or consensus mismatches regarding the =
max size of a block. =20

Type 2 consensus failures are more severe but also less likely (I=E2=80=99=
m not aware of a Type 2 consensus failure besides the 92 million bitcoin =
bug from August 2010).  If Core was to accept a rogue TX that created =
another 92 million bitcoins, I think it would be a good thing if the =
other implementations forked away from it (we don=E2=80=99t want =
bug-for-bug compatibility here).  =20

This once again reveals the benefits of multiple competing =
implementations. =20

Sincerely,
Peter=20