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From: Tomas <tomas@tomasvdw.nl>
To: Gregory Maxwell <greg@xiph.org>
Cc: Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
Subject: Re: [bitcoin-dev] Using a storage engine without UTXO-index
Date: Sat, 08 Apr 2017 09:28:48 +0200	[thread overview]
Message-ID: <1491636528.2474173.938219072.54C44183@webmail.messagingengine.com> (raw)
In-Reply-To: <CAAS2fgTWyX5M-xcELC2vDvGfs01tbGYkpZJCSeNbvn_p4Ecjqg@mail.gmail.com>

On Sat, Apr 8, 2017, at 02:44, Gregory Maxwell wrote:
> As you note that the output costs still bound the resource
> requirements. 

Resource cost is not just a measure of storage requirement; data that
needs to be accessed during peak load induce more cost then data only
used during base load or only rarely used.

> Latency related costs in Bitcoin Core also do not depend on the number
> of outputs in transactions in a block. When a transaction is handled
> it goes into an in-memory buffer and only gets flushed later if isn't
> spent before the buffer fills.  A block will take more time to
> validate with more inputs, same as you observer, but the aggregate
> resource usage for users depends significantly on outputs (so, in fact
> there is even further misaligned incentives than just the fact that
> small outputs have a outsized long term cost).

In Core, when a block comes the inputs are checked against the UTXO set
(which grows with outputs)  even if pre-synced, to verify order. Am I
wrong there? This is not in the case in bitcrust; it is instead checked
against the spend-tree (which grows with inputs).

How "significant" this is, I neither know nor claim,  but it is an
interesting difference. 

> Then I think you may want to retract the claim that "As this solution,
> reversing the costs of outputs and inputs, [...] updates to the
> protocol addressing the UTXO growth, might not be worth considering
> *protocol improvements* "

I think you are being a bit harsh here . I am also clearly explaining
the difference only applies to peak load, and just making a suggestion.
I simply want to stress the importance of protocol / implementation
separation as even though you are correct UTXO data is always a resource
cost for script validation (as I also state), the ratio of different
costs are  not necessarily *identical* across implementation. 

Note that the converse also holds: In bitcrust, if the last few blocks
contain many inputs, the peak load verification for this block is
slower. This is not the case in Core.

Tomas


  reply	other threads:[~2017-04-08  7:28 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-04-06 22:12 [bitcoin-dev] Using a storage engine without UTXO-index Tomas
2017-04-06 23:38 ` Eric Voskuil
2017-04-07  0:17   ` Tomas
2017-04-08 22:37     ` Eric Voskuil
2017-04-08 23:58       ` Tomas
2017-04-11  1:44         ` Eric Voskuil
2017-04-11  8:43           ` Tomas
2017-04-11  9:41             ` Eric Voskuil
2017-04-11 10:04               ` Tomas
     [not found] ` <CAAS2fgTEMCkDWdhCWt1EsUrnt3+Z_8m+Y1PTsff5Rc0CBnCKWQ@mail.gmail.com>
2017-04-07  0:48   ` Tomas
2017-04-07  1:09     ` Gregory Maxwell
2017-04-07  1:29       ` Tomas
2017-04-07 18:52         ` Tom Harding
2017-04-07 19:42           ` Gregory Maxwell
2017-04-08 18:27             ` Tom Harding
2017-04-08 19:23               ` Tomas
2017-04-07  7:55 ` Marcos mayorga
2017-04-07  8:47   ` Tomas
2017-04-07 14:14     ` Greg Sanders
2017-04-07 16:02       ` Tomas
2017-04-07 18:18 ` Gregory Maxwell
2017-04-07 18:39   ` Bram Cohen
2017-04-07 19:55     ` Eric Voskuil
2017-04-07 21:44       ` Tomas
2017-04-07 23:51         ` Eric Voskuil
2017-04-07 21:14     ` Tomas
2017-04-08  0:44       ` Gregory Maxwell
2017-04-08  7:28         ` Tomas [this message]
2017-04-08 19:23           ` Johnson Lau
2017-04-08 19:56             ` Tomas
2017-04-08 20:21               ` Johnson Lau
2017-04-08 20:42                 ` Tomas
2017-04-08 22:12                 ` Gregory Maxwell
2017-04-08 22:34                   ` Tomas
2017-04-08 21:22     ` Troy Benjegerdes

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