The Ethereum Sharding (Sharding) of Wangmei Quenching Thirst

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The Ethereum Sharding (Sharding) of Wangmei Quenching Thirst｜Tucaojun Roast Boy

Conflux中文社区

2021-04-25 10:51

本文约2193字，阅读全文需要约9分钟

If you keep thinking about the plums in the distance, but turn a blind eye to the stream around you, you will probably die of thirst on the road.

Not long ago, Vitalik published an article entitled "Why sharding is great: demystifying the technical properties (Why sharding is great: demystifying the technical properties)" (https://vitalik.ca/general/2021/ 04/07/sharding.html, the Chinese machine translation traces are obvious, it is recommended to read the English version), technically explained the specific attributes and sacrifices provided by Ethereum sharding in a simple and simple way. “Sharding is the future of scalability for Ethereum, and it will be key to helping the ecosystem support thousands of transactions per second and allowing much of the world to use the platform on a regular basis at an affordable cost,” the article states.

Good article, especially by defining specific properties of Ethereum shards that draw a line from "rogue shards" ("techniques with very different and often much weaker security properties" as the original article says).

Although Baozai admires V God's ability to paint big cakes and agrees that safe and reliable sharding technology is the inevitable development direction of blockchain technology in the future, he still feels uncomfortable with some mistakes in the article.

The core logic of the article is that V God believes that it is impossible for the blockchain to obtain the three attributes of scalability (Scalability), decentralization (Decentralization), and security (Security) at the same time through "simple" technology, which is the so-called "impossible triangle". ", and sharding technology can solve these problems at the same time, so "sharding is great". This logic seems reasonable at first glance, but it is specious when you think about it carefully. There are three main loopholes: "simple" technology, "impossible triangle", and the necessity of sharding.

The first is the assertion that "simple" technology cannot achieve all three properties simultaneously. What kind of technology can be called "simple" is not defined in the article. In the actual discussion, the concept was secretly changed into three "easy solutions": traditional single chains including Bitcoin and Ethereum, composed of a few High-throughput blockchains maintained by nodes (approximately referring to EOS and alliance chains), and multi-chain ecosystems (Poca and other "rogue shards" that do not guarantee security, etc.).

The logical problem with this assertion is that "simple" does not mean "easy", and the example demonstration after changing the concept is more like picking a weak persimmon because it does not exhaust all possibilities.

Similar logic has been seen in a joke before - "How to prove that all odd numbers are prime numbers? Let's take a look: 3 is a prime number, 5 is a prime number, 7 is also a prime number, and the proof is over."

Among them, the blockchain with high throughput of the second solution ("High-TPS chains") seems to be equated with the small number of nodes in V God's concept, making a mistake of circular argumentation. In short, the discussion here certainly does not consider Conflux, a solution that can achieve thousands of TPS throughput on thousands of consensus nodes.

Perhaps God V's definition of "simple" here can directly draw a line according to the effect, and all those that can solve the "impossible triangle" are all classified as "not simple" technologies, so as to ensure that logical rigor remains invincible.

Secondly, the so-called "impossible triangle" is also a long-standing misconception. Although it is often compared with the CAP theorem of distributed systems, in fact, there has never been any theoretical proof for the "blockchain impossible triangle", and it can only be regarded as a "hypothesis" or "conjecture" at best. This kind of logic that equates "I can't do it" with "impossible" has a sense of sight that I feel constipated and complain that the earth is unattractive.

Fortunately, God V seems to realize that it is unreasonable to mention the advantages of the "impossible triangle" Ethereum sharding, so he secretly added a premise in this article-"If you insist on using simple technology, then the It is impossible to obtain three attributes at the same time."

I don’t know when we can officially change the phrase “Blockchain’s Impossible Triangle” to “Blockchain Simple Technology Can’t Achieve Triangle” to set the record straight. At the same time, it is suggested to add a line of small characters "'Simple Technology' means that it cannot be obtained at the same time. These three attributes of blockchain technology".

Finally, this article is not enough to support the necessity and urgency of sharding technology. Fragmentation can certainly break the "impossible triangle" and solve the performance problems faced by Ethereum. But this is only a sufficient condition, and it cannot explain why the sharding technology must be adopted, or even why the "impossible triangle" must be broken.

In the "impossible triangle" description, the scalability requirement is that the processing power of the entire blockchain consensus system exceeds the processing power of an ordinary consumer-grade PC or laptop as a single node. In the long run, this goal must be achieved after all, but judging from the current actual situation of Ethereum, this goal is too ambitious. With the current computer performance, a single computer is enough to process thousands or even tens of thousands of transactions per second, while Ethereum can only process no more than 50 transactions, which is far from reaching the bottleneck. Sharding based on the current performance of Ethereum is like a child who has not learned mathematics in elementary school and insists on learning advanced mathematics.

Therefore, even if sharding can solve the problems faced by Ethereum, it does not mean that sharding must be used to solve it. Compared with when the concept of Ethereum sharding was first proposed, there are now many ready-made solutions including high-performance consensus algorithms such as Conflux and second-layer expansion solutions such as Rollup. If you insist on doing sharding in a stubborn way, it means that you will go all the way to the dark.

In addition to the loopholes in the core logic, the sacrifice of the sharding itself in terms of security, reliability, and performance is also very obvious. V God has already explained it in detail in the article, so I won’t repeat it here.

There is only one point to be corrected here: sharding will inevitably reduce the user experience, and the problem of increasing the waiting time for confirming users is inevitable, and it does not only exist in the scheme of fraud proof. Although proof technologies such as ZK-SNARK can greatly improve the verification efficiency of transactions and ensure that transactions can be quickly confirmed after being uploaded to the chain, such technologies require a long time to generate proofs without exception. Therefore, from the user's perspective, the cost of using ZK-SNARK technology to reduce the waiting time after the transaction is on the chain is to increase the time to wait for the proof to be generated before going on the chain, and the overall experience may not be much improved. Those who hope to rely on ZK-SNARK to solve the delay problem caused by fragmentation should review the story of change and change.

To sum up, Bazai believes that the sharding technology of Ethereum is like the plum in the story of wishing for plums and quenching thirst. It can be inspiring but has little practical significance. If you keep thinking about the plums in the distance, but turn a blind eye to the stream around you, you will probably die of thirst on the road.

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