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From: Johnson Lau <jl2012@xbt.hk>
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Date: Sun, 9 Apr 2017 03:23:29 +0800
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To: Tomas <tomas@tomasvdw.nl>,
	bitcoin-dev <bitcoin-dev@lists.linuxfoundation.org>
Subject: Re: [bitcoin-dev] Using a storage engine without UTXO-index
Precedence: list


> On 8 Apr 2017, at 15:28, Tomas via bitcoin-dev =
<bitcoin-dev@lists.linuxfoundation.org> wrote:
>>=20
>=20
> 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.=20
>=20
> 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.
>=20
> Tomas
>=20

I don=E2=80=99t fully understand your storage engine. So the following =
deduction is just based on common sense.

a) It is possible to make unlimited number of 1-in-100-out txs

b) The maximum number of 100-in-1-out txs is limited by the number of =
previous 1-in-100-out txs

c) Since bitcrust performs not good with 100-in-1-out txs, for anti-DoS =
purpose you should limit the number of previous 1-in-100-out txs.=20

d) Limit 1-in-100-out txs =3D=3D Limit UTXO growth

I=E2=80=99m not surprised that you find an model more efficient than =
Core. But I don=E2=80=99t believe one could find a model that doesn=E2=80=99=
t become more efficient with UTXO growth limitation.

Maybe you could try an experiment with regtest? Make a lot 1-in-100-out =
txs with many blocks, then spend all the UTXOs with 100-in-1-out txs. =
Compare the performance of bitcrust with core. Then repeat with =
1-in-1-out chained txs (so the UTXO set is always almost empty)

One more question: what is the absolute minimum disk and memory usage in =
bitcrust, compared with the pruning mode in Core?=