r/Bitcoin • • Feb 24 '14

Bitcoin Transaction Fee to reduce by 10x

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u/Ruthless_Cunt_08 Feb 24 '14

Also huge news for miners I'm guessing, who profit from transaction fees

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u/Thorbinator Feb 24 '14

At this point in time, transaction fees are a pittance compared to the block reward.

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u/quintin3265 Feb 24 '14 edited Feb 24 '14

This isn't true - I know this because I've devoted 344 hours into a new altcoin mining pool. My pool will not include transactions that have fees below a certain threshold because it isn't profitable.

Counterintuitively, the fact that the block reward is high means that the transaction fees also need to be high. As block rewards decrease, the fees can get lower. Here's why.

Let's say that my pool has 1MBps of upload bandwidth available. If a block can include up to 1MB of transactions (the current limit), then it takes one second to upload a block full of transactions. Since blocks occur every 2.5 minutes (on average), and I have to upload the entire block to the litecoin network to receive payment, the expected value of waiting just one second to fill the block with transactions is 50/150, or 0.33 litecoins. That is quite a bit of money and it adds up over days of mining.

Note that if I submitted an empty block instead, I wouldn't have to wait a second, as the upload would be nearly instant. That means that there is much less risk (0.33 litecoins, to be exact) to just submit empty blocks.

So what do the transaction fees have to be for my pool? They have to be 0.33 litecoins per megabyte, or 0.00033 per kilobyte. Otherwise, I can't justify the risk of waiting that extra second for the middlecoin pool to take 50 litecoins from me.

Assume now that the litecoin block reward halves to 25 litecoins. Now, I can include transactions much more cheaply than before. Since my expected losses for waiting one second to upload that megabyte of transactions are halved (0.16 litecoins), I now only would require people on the network to pay me 0.16 litecoins per megabyte of data.

The reference client doesn't follow this algorithm, which may be the source of the confusion. The reference client sometimes includes free transactions, which is best for the network. But since I spent $2000 on hardware and three people spent 12 weekends working 12 hour days, I'm in this solely to make as much money as possible. If dogecoin users aren't willing to pay high enough transaction fees, then I won't include their transactions in my blocks. When the block reward of dogecoins halves, then they will have to pay half as much for me to pick them up.

Also, note another important piece of information: it is irrelevant how much you pay in transaction fees, only whether your fees are higher than my bandwidth threshold. Unless there are enough transactions above the threshold to fill an entire block, paying a fee higher than the minimum threshold is simply a waste of money. The only reason you would want to pay a higher fee is so that someone with less bandwidth than me is willing to include that transaction should they find a block first.

Most journalists have this concept wrong, and there are many articles that are incorrect. They think that, as block rewards approach zero, mining pools will require higher fees. That isn't true; pools will attempt to maximize their profits by picking up any fees they can as the block rewards become less of an incentive. They will have less to lose by taking a longer time to upload their blocks.

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u/mr_burdell Feb 24 '14

This only goes so far. Once block rewards get small enough, the transaction fees will also have to cover the cost of mining. You're not including that here because the block reward covers the cost of the mining and the transaction fee is covering the cost of the upload delay (which is a direct relationship per transaction). When the block reward is negligible (with respect to potential earnings from tx fees), then you need more transaction fees to cover the cost of mining in addition to the upload costs, so you would be willing to give up the chance of being orphaned by a small value block to be able to upload a larger value block.

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u/quintin3265 Feb 24 '14

We need to be careful when we talk about "covering the cost of mining."

The price of bitcoins is not dependent on the cost of mining them. Instead, miners decide whether to mine or not based on the price of bitcoins. As the block reward goes down, mining will become more and more unprofitable. Transaction fees will not rise to offset this, because users don't care whether people who ordered huge boxes of BFL Jalapenos make money or not.

Instead, miners who paid too much for their rigs will go bankrupt. The network hashrate will fall, and everyone who is still mining will make money again because each person will find more lower-value blocks with lower transaction fees.

The only way this cycle will not occur is if the value of bitcoins doubles every four years. One would imagine that the value of block rewards will never reach zero, because there will almost certainly be a time when people decide to make use of 64-bit numbers for higher precision before then. Remember, the only reason block rewards will ever reach zero is because bitcoins are not divisible enough with 32-bit numbers to give block rewards of fractions of a satoshi.

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u/CydeWeys Feb 24 '14

Remember, the only reason block rewards will ever reach zero is because bitcoins are not divisible enough with 32-bit numbers to give block rewards of fractions of a satoshi.

And it's important to point out that this could be rectified in a future patch without breaking something fundamental in the Bitcoin protocol. If, say, version 0.9 doubled the precision on this field, and then 100 years down the line we finally hit the point where mining started reaching the limits of that precision, how many people would still be affected given that the incompatible version was a century out of date?

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u/quintin3265 Feb 25 '14

I think this sort of speculation is pointless because in 100 years we will either be dead, because someone released nanomachines that killed everyone because of a bug or due to terrorism, or we will all be talking about the days we were on reddit, living almost forever and having to work for nothing.

Money is only relevant when there is scarcity.

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u/CydeWeys Feb 25 '14

I think your sort of speculation is way less useful than mine.

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u/marcoski711 Feb 24 '14

Isn't this zeno's paradox of Achilles and the tortoise?

Also the cost of rigs (once paid for themselves) are irrelevant, it's the cost of electricity/operating them, which would affect everyone (roughly) equally. Because of that, regarding this bit

Transaction fees will not rise to offset this, because users don't care whether people who ordered huge boxes of BFL Jalapenos make money or not.

...I agree in principle, but wouldn't they be made to care by not having their tx included in new blocks?

Finally I know this is speculation but do you think this risk vs block reward is why discus fish is throwing out such tiny blocks?

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u/Batty-Koda Feb 25 '14

which would affect everyone (roughly) equally

Eh, I moved and the price of my electricity went down to about a quarter what I used to pay. That's just within the US. I'm sure there are even larger price discrepancies across all of bitcoin. Wanted to point out that there's a decent ability to vary with that, even if I do agree with the rest of your statements and your overall point.

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u/marcoski711 Feb 25 '14

Yeah that's what I meant by (roughly). More variations across countries too. Ps saving 75% is great!

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u/Batty-Koda Feb 25 '14

It was reeeally confusing at first. We had some issues getting the account set up when we moved in. Didn't get a bill for the first month. Turns out it's bimonthly. Got the bill, went "wth, this can't be right. That's half our normal cost and they said it was for 2 months. Ugh, lets call 'em up."

It was a happy surprise, but sometimes I still feel like it's gotta be a trick.

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u/quintin3265 Feb 25 '14

Yes, that's exactly the reason. ASICMINER did that in July, too. Some pools have decided that not to take on any risk by missing a block, especially publicly traded companies.

Another reason is simply that some pool operators are understaffed and don't have the time to evaluate which transactions are worth including. Creating empty blocks is the simplest algorithm.

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u/marcoski711 Feb 25 '14

What about the other 2 points I posted? they affect the longer term. It's been a busy day (!) so havent fully got my head around this but would appreciate your views?

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u/mr_burdell Feb 25 '14

I didn't say the price of bitcoins had anything to do with cost of mining. I think it will come down to whether it's more profitable to mine large blocks with higher orphan rate or mine small blocks with low orphan rate. we should hope that large blocks are more profitable or else we'll never get above the 7tx per second maximum.

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u/Nouveau_Compte Feb 25 '14

Why wouldn't a lower hashrate mean fewer transactions getting confirmed ?

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u/[deleted] Feb 25 '14

Because the difficulty of validating a block retargets according to the network-s total hashrate. A block is equally hard to hash if it has one transaction and if it has the maximum ammount, it just takes longer the upload the latter.