> A Header-PoW-verifying client could still be given all transactions in a recent block, from which it can see the in-band fees directly. 

You don't know the fees paid by any given transaction unless you also have all it's inputs. Transaction inputs do not include an amount. You could however get the average fee-per-kb paid by all transactions in a block by looking at the coinbase transaction, subtracting the block reward, and dividing by the size of block minus the header.


Aaron Voisine
co-founder and CEO
breadwallet.com

On Thu, Jun 11, 2015 at 11:30 AM, Nathan Wilcox <nathan@leastauthority.com> wrote:
On Wed, Jun 10, 2015 at 2:03 PM, Peter Todd <pete@petertodd.org> wrote:
On Wed, Jun 10, 2015 at 02:00:27PM -0600, Nathan Wilcox wrote:
> On Wed, Jun 10, 2015 at 1:19 PM, Aaron Voisine <voisine@gmail.com> wrote:
>
> > It could be done by agreeing on a data format and encoding it in an
> > op_return output in the coinbase transaction. If it catches on it could
> > later be enforced with a soft fork.
> >
> >
> Sounds plausible, except SPV protocols would need to include this coinbase
> txn if it's going to help SPV clients. (Until a softfork is activated, SPV
> clients should not rely on this encoding, since until that time the results
> can be fabricated by individual miners.)

Fee stats can always be fabricated by individual miners because fees can
be paid out-of-band.


This is a point I hadn't considered carefully before. I don't understand the marketplace here or why miners would want to move fees outside of explicit inband fees. Implicit in this proposal is that the statistics only cover in-band data, because that's the scope of consensus rules, and thus the proposal is only as useful as the information of in-band fees is useful.

I've also noticed a detracting technical argument given a particular tradeoff:

A Header-PoW-verifying client could still be given all transactions in a recent block, from which it can see the in-band fees directly.  The trade-off is the size of those transactions versus the need to alter any consensus rules or do soft forks.

Notice how this trade-off's costs change with maximum block size.


 
--
'peter'[:-1]@petertodd.org
00000000000000001245bd2f5c99379ee76836227ded9c08324894faabc0d27f



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Nathan Wilcox
Least Authoritarian

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