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From: Thomas Guyot-Sionnest <dermoth@aei.ca>
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Subject: Re: [bitcoin-dev] Solving the Scalability Problem on Bitcoin
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Pruning is already implemented in the nodes... Once enabled only unspent
inputs and most recent blocks are kept. IIRC there was also a proposal
to include UTXO in some blocks for SPV clients to use, but that would be
additional to the blockchain data.
Implementing your solution is impossible because there is no way to
determine authenticity of the blockchain mid way. The proof that a block
hash leads to the genesis block is also a proof of all the work that's
been spent on it (the years of hashing). At the very least we'd have to
keep all blocks until a hard-coded checkpoint in the code, which also
means that as nodes upgrades and prune more blocks older nodes will have
difficulty syncing the blockchain.
Finally it's not just the addresses and balance you need to save, but
also each unspent output block number, tx position and script that are
required for validation on input. That's a lot of data that you're
suggesting to save every 1000 blocks (and why 1000?), and as said
earlier it doesn't even guarantee you can drop older blocks. I'm not
even going into the details of making it work (hard fork, large block
sync/verification issues, possible attack vectors opened by this...)
What is wrong with the current implementation of node pruning that you
are trying to solve?
--
Thomas
On 26/08/17 03:21 PM, Adam Tamir Shem-Tov via bitcoin-dev wrote:
>
> <B> Solving the Scalability issue for bitcoin </B> <BR>
>
> I have this idea to solve the scalability problem I wish to make public=
=2E
>
> If I am wrong I hope to be corrected, and if I am right we will all
> gain by it. <BR>
>
> Currently each block is being hashed, and in its contents are the hash
> of the block preceding it, this goes back to the genesis block.
>
> <BR>
>
> What if we decide, for example, we decide to combine and prune the
> blockchain in its entirety every 999 blocks to one block (Genesis
> block not included in count).
>
> <BR>
>
> How would this work?: Once block 1000 has been created, the network
> would be waiting for a special "pruned block", and until this block
> was created and verified, block 1001 would not be accepted by any nodes=
=2E
>
> This pruned block would prune everything from block 2 to block 1000,
> leaving only the genesis block. Blocks 2 through 1000, would be
> calculated, to create a summed up transaction of all transactions
> which occurred in these 999 blocks.
>
> <BR>
>
> And its hash pointer would be the Genesis block.
>
> This block would now be verified by the full nodes, which if accepted
> would then be willing to accept a new block (block 1001, not including
> the pruned block in the count).
>
> <BR>
>
> The new block 1001, would use as its hash pointer the pruned block as
> its reference. And the count would begin again to the next 1000. The
> next pruned block would be created, its hash pointer will be
> referenced to the Genesis Block. And so on..
>
> <BR>
>
> In this way the ledger will always be a maximum of 1000 blocks.
>
>
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Pruning is already implemented in the nodes... Once enabled only
unspent inputs and most recent blocks are kept. IIRC there was also
a proposal to include UTXO in some blocks for SPV clients to use,
but that would be additional to the blockchain data.<br>
<br>
Implementing your solution is impossible because there is no way to
determine authenticity of the blockchain mid way. The proof that a
block hash leads to the genesis block is also a proof of all the
work that's been spent on it (the years of hashing). At the very
least we'd have to keep all blocks until a hard-coded checkpoint in
the code, which also means that as nodes upgrades and prune more
blocks older nodes will have difficulty syncing the blockchain.<br>
<br>
Finally it's not just the addresses and balance you need to save,
but also each unspent output block number, tx position and script
that are required for validation on input. That's a lot of data that
you're suggesting to save every 1000 blocks (and why 1000?), and as
said earlier it doesn't even guarantee you can drop older blocks.
I'm not even going into the details of making it work (hard fork,
large block sync/verification issues, possible attack vectors opened
by this...)<br>
<br>
What is wrong with the current implementation of node pruning that
you are trying to solve?<br>
<br>
--<br>
Thomas<br>
<br>
<div class="moz-cite-prefix">On 26/08/17 03:21 PM, Adam Tamir
Shem-Tov via bitcoin-dev wrote:<br>
</div>
<blockquote
cite="mid:CACQPdjphPmSC7bmicXGytuD3YAXYmsEGOECTTTuLfB_5iqDQGw@mail.gmail.com"
type="cite">
<div dir="ltr">
<p style="margin-bottom:0in;line-height:100%"><B> Solving
the Scalability issue for bitcoin </B> <BR></p>
<p style="margin-bottom:0in;line-height:100%">I have this idea
to
solve the scalability problem I wish to make public.</p>
<p style="margin-bottom:0in;line-height:100%">If I am wrong I
hope
to be corrected, and if I am right we will all gain by it.
<BR></p>
<p style="margin-bottom:0in;line-height:100%">Currently each
block
is being hashed, and in its contents are the hash of the block
preceding it, this goes back to the genesis block.</p>
<p style="margin-bottom:0in;line-height:100%"><BR></p>
<p style="margin-bottom:0in;line-height:100%">What if we decide,
for example, we decide to combine and prune the blockchain in
its
entirety every 999 blocks to one block (Genesis block not
included in
count).</p>
<p style="margin-bottom:0in;line-height:100%"><BR></p>
<p style="margin-bottom:0in;line-height:100%">How would this
work?: Once block 1000 has been created, the network would be
waiting
for a special "pruned block", and until this block was
created and verified, block 1001 would not be accepted by any
nodes.</p>
<p style="margin-bottom:0in;line-height:100%">This pruned block
would prune everything from block 2 to block 1000, leaving
only the
genesis block. Blocks 2 through 1000, would be calculated, to
create
a summed up transaction of all transactions which occurred in
these
999 blocks.</p>
<p style="margin-bottom:0in;line-height:100%"><BR></p>
<p style="margin-bottom:0in;line-height:100%">And its hash
pointer
would be the Genesis block.</p>
<p style="margin-bottom:0in;line-height:100%">This block would
now
be verified by the full nodes, which if accepted would then be
willing to accept a new block (block 1001, not including the
pruned
block in the count).</p>
<p style="margin-bottom:0in;line-height:100%"><BR></p>
<p style="margin-bottom:0in;line-height:100%">The new block
1001,
would use as its hash pointer the pruned block as its
reference. And
the count would begin again to the next 1000. The next pruned
block
would be created, its hash pointer will be referenced to the
Genesis
Block. And so on..</p>
<p style="margin-bottom:0in;line-height:100%"><BR></p>
<p style="margin-bottom:0in;line-height:100%">In this way the
ledger will always be a maximum of 1000 blocks.</p>
<br>
</div>
</blockquote>
<br>
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