An Incomplete Guide to Ethereum Rollups • Hacker News Board

Re: An Incomplete Guide to Ethereum Rollups

#21

Post by dboreham » Wed, Jan 06, 2021, 2:42 PM UTC

DennisP wrote: post #17

dboreham wrote: post #16

Earlier quoted context omitted.

Not sure about pseudo-science, but I have found blockchain writings to be on the abstract side. Try this interpretation: The Ethereum blockchain hosts serious money. However it has poor cost and performance characteristics for many potential use cases. One approach to work around those is to move money temporarily from Ethereum to another blockchain (let's call that the secondary chain) that's cheaper/faster; shuffle…

One difference between rollups and sidechains is that with rollups the essential data is stored on the main chain, in compressed form.

Fwiw I disagree that the "data availability" concern is real. My take is that anyone with an interest in having some data will go ahead and store that data. If data integrity needs to be preserved under consensus then publish a hash to a blockchain. Possibly we're actually agreeing on this in your use of "essential"?

Re: An Incomplete Guide to Ethereum Rollups

#22

Post by DennisP » Thu, Jan 07, 2021, 11:14 PM UTC

dboreham wrote: post #21

DennisP wrote: post #17

Earlier quoted context omitted.

One difference between rollups and sidechains is that with rollups the essential data is stored on the main chain, in compressed form.

Fwiw I disagree that the "data availability" concern is real. My take is that anyone with an interest in having some data will go ahead and store that data. If data integrity needs to be preserved under consensus then publish a hash to a blockchain. Possibly we're actually agreeing on this in your use of "essential"?

By "essential" I mean all the data required to recover complete state.

Holding the data you need yourself might work ok for your own personal ETH balance, assuming you have some way to prove the absence of any outgoing transfers. In fact, that's how one variant of Plasma works.

But with smart contracts, it gets a lot more complicated. It's way simpler if you can just know that any data you need will be on the network.

Re: An Incomplete Guide to Ethereum Rollups

#23

Post by simonebrunozzi » Sat, Jan 09, 2021, 11:49 AM UTC

xorcist wrote: post #13

Why not use a sidechain instead? They can compress transactions at least as effective, and have more simple security properties. The main drawback with sidechains are that they are hard to run decentralized in any credible sense. Basically just as hard as the blockchain in the first layer sense. They seem to be identical in this regard.

As HN user timdaub stated earlier in the thread,

> in order to transact "off-chain", a user had to transfer some money into a bridge

I believe that this is the main problem with side chains.

Re: An Incomplete Guide to Ethereum Rollups

#24

Post by fbrusch » Sun, Jan 10, 2021, 5:23 PM UTC

xorcist wrote: post #13

Why not use a sidechain instead? They can compress transactions at least as effective, and have more simple security properties. The main drawback with sidechains are that they are hard to run decentralized in any credible sense. Basically just as hard as the blockchain in the first layer sense. They seem to be identical in this regard.

Sidechains have different security properties. You probably know xdai (https://www.xdaichain.com/), where you can transact tokens that "wrap" dais from Ethereum mainnet. The sidechain is secured by a proof of authority consensus, where you require a fraction of validators to behave honestly. If a certain number of validators collude, they can do nasty things, such as censoring transactions from a certain address, or keeping the chain from making progress. This is not possible in a rollup, either optimistic or zk, because any single user can always commit a batch or report fraud on L1, so you just need a single honest actor for things to work.