Sub 1s/vb transactions \ stacker news ~ideasfromtheedge

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297 sats \ 22 comments \ @88b0c423eb 3 Oct ideasfromtheedge

What can be some bad consequences and good use cases for sub 1s/vb txs? Can a mempool be attacked with too much txs? How does it affect LN? Maybe more financial tarnsactions in the timechain and less spam? Maybe more spam?

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121 sats \ 3 replies \ @Murch 3 Oct

Bitcoin Core limits the amount of memory dedicated to the mempool data structure to 300 MiB by default. When this memory limit is reached, your node will start evicting transactions with the lowest descendant feerate (a heuristic for what’s going to be mined last), and then increase its minimum feerate to the feerate of the last evicted transaction + 1×incrementalRelayTxFee. If “too many transactions get submitted”, there still will only be one block full of transactions added to the blockchain every block. More competition for blockspace means that the minimum feerate in the block is pushed up. Higher feerates means that the subjective value of transactions must be higher for the senders to bid sufficient fees for the transaction to get into the block. That’s bad news for transactions whose subjective value is low. I’ll leave it up to you to categorize whether that would apply to LN transactions or not.

Accepting transactions below 1 s/vB means that it cheaper transactions can be used to fill up the mempool. It makes the price discovery for blockspace more finegrained, but doesn’t fundamentally change the mechanism to reach the equilibrium. If there is low blockspace demand, there might be a few more transactions added to the blockchain that otherwise would not have occurred. It also makes consolidation of a lot of the UTXOs created in the past two years much more financially viable.

0 sats \ 2 replies \ @88b0c423eb OP 3 Oct

nice recall good to set the mempool at least at 2GB, but also we must aknowledge the different mempools. Those running knots are almost empty, core without filters full 300mb more or less.

0 sats \ 1 reply \ @Murch 3 Oct

I don’t understand why it would be “good to set the mempool to at least 2 GB”. Could you explain what you are trying to achieve with that?

0 sats \ 0 replies \ @88b0c423eb OP 3 Oct

To not discard txs with sub 1s/vb, they may passed at night

21 sats \ 14 replies \ @OT 3 Oct

I think it was Floppydisk who said something like it makes it 10x cheaper to attack.

My understanding is that still if someone wants to spam the chain with sub 1 sat TX you can simply outbid them by paying 2 sats/vb.

71 sats \ 8 replies \ @Scoresby 3 Oct

In my ignorance, I don't see how it makes it cheaper to attack. If the attack is filling mempools with cheap transactions, the solution is paying more for your non-attack transactions.

if you used to have to pay a minimum of 1 sat/vB and the feerate is lowered, so now everyone is paying 0.1 sat/vB, but then attackers DoS mempools with lots of these transactions so you have to pay 1 sat/vB to get your transaction confirmed...nothing happened?

0 sats \ 7 replies \ @OT 3 Oct

Yes, that's the way I see it.

Though there could be other less obvious things that it could have an effect on like sone extra compute or taking up bandwidth.

21 sats \ 6 replies \ @Scoresby 3 Oct

@murch pointed out one of the biggest effects:

I believe prior to this summer, most wallets implemented changes to fee rates in whole sat terms. So, if you wanted to fee bump your 1 sat/vB transaction, the wallet only let you choose 2 or more sats/vB.

As more wallets allow implement tooling for sub 1 sat/vB, you could conceivaly fee bump to 1.1 sats/vB.

This means miners may actually see a loss in revenue because fee rates may not escalate as quickly as they used to. (hopefully I'm recounting this correctly).

102 sats \ 0 replies \ @Murch 3 Oct

Yes, good summary.

The minRelayTxFee and incrementalRelayTxFee both express a minimum cost for relaying data across the network. It would be a bit odd to charge more for the first announcement of a transaction, but then make it cheaper to replace the transaction, or vice versa to make it cheap to make a first announcement and expensive to replace a transaction. So both mempool policies were lowered from 1 s/vB to 0.1 s/vB in Bitcoin Core 29.1 and the upcoming v30.0.

0 sats \ 4 replies \ @OT 3 Oct

I remember hearing that pleb nodes are rejecting a lot of these TX as they still have the default 1sat/vb minimum. I guess since they have swamped the mempool that they eventually get relayed to most mining pools and into a block.

102 sats \ 0 replies \ @Murch 3 Oct

Bitcoin Core 29.1 already makes up over 13% of the listening nodes according to Clark Moody’s dashboard:

As Laurent has recently demonstrated with his simulation, below 90% filters, almost all corresponding transactions reliably reach non-filtering listening nodes (which I suspect miners to be). So, at this point any listening nodes that want the low feerate transactions should be receiving them reliably before they appear in blocks.

50 sats \ 2 replies \ @Scoresby 3 Oct

Miners are already mining blocks with average fee rates that are sub 1 sat/VB transactions in something close to half the blocks. (Although past couple weeks not as much maybe)

202 sats \ 1 reply \ @Murch 3 Oct

The recent blocks were including fewer transactions below 1 s/vB, because enough transactions were bidding more than 1 s/vB:

Chart: last 24h, inverted feerate (highest feerate at the bottom), only txs offering 1 s/vB or more.

21 sats \ 0 replies \ @Scoresby 3 Oct

Markets at work! Thanks for these replies.

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0 sats \ 4 replies \ @88b0c423eb OP 3 Oct

cheaper to attack but also cheaper for transac, it depends on human action. One thing that is a problem is that bitcoin onchain is not being used much.

0 sats \ 3 replies \ @OT 3 Oct

We'll see how long it stays like this. All it takes is a major exchange or ETF fund to get hacked and we might not see sub 100sats/vb for some time.

0 sats \ 2 replies \ @88b0c423eb OP 3 Oct

Why an exchange or ETF being hacked would increase fee rates?

10 sats \ 1 reply \ @OT 3 Oct

Because they would realize why they should be holding their own keys!

0 sats \ 0 replies \ @88b0c423eb OP 3 Oct

Oh you mean a lot of people transacting at the same time, got it. But that's also a temporary problem and suply and demand for block space can be high or lower with more or less LN use also.

0 sats \ 2 replies \ @openyoureyes 3 Oct

Sub 1sat tx are not good but there is nearly no way of not allowing it. Because the miners decide what comes into next block, not the noderunners. And they will mine everything if the block has space left.

But i think it can be a attack vector. What if some bad entity with a few btc spams your address with very cheap dust tx? You realize it later when you want to spend onchain and you move these utxo. When we are back at 100sat or 1000sat/vbyte these people will lose a big amount to miners.

0 sats \ 0 replies \ @88b0c423eb OP 3 Oct

This desribed kind of attack is very niche and hard to see in the wild, overall imo sub 1s/vb is a positive thing for the majority of people, and precisely because of that likely there will be much more txs onchain, but it will always be low because of LN , so 1000/vb may never come. Then there's CISA that may change things a lot again.

0 sats \ 0 replies \ @Murch 3 Oct

When someone sends you dust outputs, you can simply choose not to spend those outputs specifically, especially if they cost more than they are worth.