Difference between revisions of "The Scalability Trilemma"
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== Basics == | == Basics == | ||
* From the [https://vitalik.ca/general/2021/04/07/sharding.html blog] of [[Vitalik Buterin|Vitalik]] (7-4-2021): | * The classic framing goes "A blockchain can only have two of these three properties: scalability, security and [[Decentralized|decentralization]]." | ||
*From the [https://vitalik.ca/general/2021/04/07/sharding.html blog] of [[Vitalik Buterin|Vitalik]] (7-4-2021): | |||
''"The scalability trilemma says that there are three properties that a [[blockchain]] try to have, and that, if you stick to "simple" techniques, you can only get two of those three. The three properties are:'' | ''"The scalability trilemma says that there are three properties that a [[blockchain]] try to have, and that, if you stick to "simple" techniques, you can only get two of those three. The three properties are:'' | ||
# ''Scalability: the chain can process more [[Transaction (Tx)|transactions]] than a single regular [[node]] (think: a consumer laptop) can verify.'' | # ''Scalability: the chain can process more [[Transaction (Tx)|transactions]] than a single regular [[node]] (think: a consumer laptop) can verify.'' | ||
# '' | # ''Decentralization: the chain can run without any trust dependencies on a small group of large centralized actors. This is typically interpreted to mean that there should not be any trust (or even honest-majority assumption) of a set of nodes that you cannot join with just a consumer laptop.'' | ||
# ''Security: the chain can resist a large percentage of participating nodes trying to attack it (ideally 50%; anything above 25% is fine, 5% is definitely not fine).'' | # ''Security: the chain can resist a large percentage of participating nodes trying to attack it (ideally 50%; anything above 25% is fine, 5% is definitely not fine).'' | ||
Latest revision as of 08:00, 31 October 2022
Basics
- The classic framing goes "A blockchain can only have two of these three properties: scalability, security and decentralization."
- From the blog of Vitalik (7-4-2021):
"The scalability trilemma says that there are three properties that a blockchain try to have, and that, if you stick to "simple" techniques, you can only get two of those three. The three properties are:
- Scalability: the chain can process more transactions than a single regular node (think: a consumer laptop) can verify.
- Decentralization: the chain can run without any trust dependencies on a small group of large centralized actors. This is typically interpreted to mean that there should not be any trust (or even honest-majority assumption) of a set of nodes that you cannot join with just a consumer laptop.
- Security: the chain can resist a large percentage of participating nodes trying to attack it (ideally 50%; anything above 25% is fine, 5% is definitely not fine).
Now we can look at the three classes of "easy solutions" that only get two of the three:
- Traditional blockchains - including Bitcoin, pre-PoS/sharding Ethereum, Litecoin, and other similar chains. These rely on every participant running a full node that verifies every transaction, and so they have decentralization and security, but not scalability.
- High-TPS chains - including the DPoS family but also many others. These rely on a small number of nodes (often 10-100) maintaining consensus among themselves, with users having to trust a majority of these nodes. This is scalable and secure (using the definitions above), but it is not decentralized.
- Multi-chain ecosystems - this refers to the general concept of "scaling out" by having different applications live on different chains and using cross-chain-communication protocols to talk between them. This is decentralized and scalable, but it is not secure, because an attacker need only get a consensus node majority in one of the many chains (so often <1% of the whole ecosystem) to break that chain and possibly cause ripple effects that cause great damage to applications in other chains."
