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From: "David A. Harding" <dave@dtrt.org>
To: Sjors Provoost <sjors@sprovoost.nl>,
	Bitcoin Protocol Discussion
	<bitcoin-dev@lists.linuxfoundation.org>
Subject: Re: [bitcoin-dev] Transaction Merging (bip125 relaxation)
Date: Sun, 28 Jan 2018 12:29:48 -0500	[thread overview]
Message-ID: <20180128172948.5y32cc6rvf3saolj@fedora-23-dvm> (raw)
In-Reply-To: <36682FF4-5C68-4610-9E82-FCE6F93E050F@sprovoost.nl>

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On Sun, Jan 28, 2018 at 05:43:34PM +0100, Sjors Provoost via bitcoin-dev wrote:
> Peter Todd wrote:
> > In fact I considered only requiring an increase in fee rate, based on the
> > theory that if absolute fee went down, the transaction must be smaller and thus
> > miners could overall earn more from the additional transactions they could fit
> > into their block. But to do that properly requires considering whether or not
> > that's actually true in the particular state the mempool as a whole happens to
> > be in, so I ditched that idea early on for the much simpler criteria of both a
> > feerate and absolute fee increase.
> 
> Why would you need to consider the whole mempool? 

Imagine a miner is only concerned with creating the next block and his
mempool currently only has 750,000 vbytes in it.  If two 250-vbyte
transactions each paying a feerate of 100 nanobitcoins per vbyte (50k
total) are replaced with one 325-vbyte transaction paying a feerate of
120 nBTC (39k total), the miner's potential income from mining the next
block is reduced by 11k nBTC.

Moving away from this easily worked example, the problem can still exist
even if a miner has enough transactions to fill the next block.  For
replacement consideration only by increased feerate to be guaranteed
more profitable, one has to assume the mempool contains an effectively
continuous distribution of feerates.  That may one day be true of the
mempool (it would be good, because it helps keep block production
regular sans subsidy) but it's often not the case these days.

-Dave

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  reply	other threads:[~2018-01-28 17:30 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-22 17:40 [bitcoin-dev] Transaction Merging (bip125 relaxation) Rhavar
2018-01-22 18:16 ` Alan Evans
2018-01-22 18:18   ` Rhavar
2018-01-22 18:50     ` Moral Agent
2018-01-22 18:59       ` Rhavar
2018-01-22 20:00 ` Peter Todd
2018-01-22 20:09   ` Rhavar
2018-01-23 16:31   ` Rhavar
2018-01-23 21:56     ` Moral Agent
2018-01-23 22:19       ` Rhavar
2018-01-23 22:49         ` Gregory Maxwell
2018-01-24  7:44           ` Peter Todd
2018-01-24 13:43             ` Alan Evans
2018-01-24 16:05               ` Rhavar
2018-01-28 16:43                 ` Sjors Provoost
2018-01-28 17:29                   ` David A. Harding [this message]
2018-01-28 17:58                     ` Rhavar
2018-01-28 18:08                     ` Moral Agent
2018-01-23 21:31   ` Gregory Maxwell
2018-01-24  7:28     ` Peter Todd
2018-01-23 23:31 Adam Ficsor

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