Fuel Founder Nick Didson points out that most of the technical solutions for blockchain scalability have been found, but there is no proper way to handle the issue of state expansion. What is state expansion? How can this problem be reduced? These are questions that every decentralized network will need to consider sooner or later.
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State expansion is the ultimate boss of scalability
Key technologies for blockchain scalability
No solution for state growth currently
Rollups cannot solve the problem of state growth
The higher the efficiency, the larger the state
Possible solutions for state expansion
Allowing state development
Cost of state space
Stateless design
Un-Merkalizing the state
Application-level state compression
State expansion is no longer a future problem
The Web3 industry has been striving for efficiency for many years and seems to be approaching the end. However, the ultimate boss on the road to blockchain scalability, state expansion, currently does not have a solution. Perhaps this problem will become the final and biggest bottleneck in scalability.
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Key technologies for blockchain scalability
In terms of blockchain scalability, there are three main technical issues that need to be addressed: execution efficiency, data availability (DA), and state size control. So far, the first two have clear solutions:
Execution:
Ensuring the correct synchronization, verification, and block creation of transactions in decentralized networks. This bottleneck has been resolved, for example, with the introduction of more efficient virtual machines (FuelVM, Stylus, SVM, MoveVM) on the market, or parallel transaction execution methods, and better pre-compilation.
Data availability and storage:
Ensuring synchronization with the blockchain network during state transitions and supporting fraud-proof or validity-proof verification of rollups. Similarly, there are many solutions to this problem, such as the introduction of the Cancun upgrade EIP-4844, sharding design, and external data availability layer provided by Celestia, EigenDA, and Avail.
State:
State refers to the “latest ledger information of the decentralized network,” which includes all account data and token distributions in the network. In order to allow nodes to access it quickly, state data usually needs to be accessed on disks, making it the slowest process in transactions, apart from signature and hashing. As the network’s usage time increases, the state size continues to expand.
Among them, the state grows over time and is often seen as a “future problem” that is ignored. The problem of state growth currently has almost no good solutions in all fields. If this problem cannot be mitigated, it will slow down blockchain transaction times and increase storage costs, gradually burdening node operations, and ultimately hinder the wider adoption of blockchain technology.
Rollups cannot solve the problem of state growth
Existing solutions for Rollups only address the execution layer issue, and some modular solutions such as Celestia further address the data availability issue. However, if these new solutions cannot solve the core problem of state expansion, the blockchain industry will return to a zero-sum game.
If state growth cannot be resolved, all scalability technology iterations so far will be in vain. Regardless of the network, they will eventually be limited by state expansion, regardless of how the execution or data environment is designed.
Nick believes that solving the problem of state growth will become the next catalyst for the Rollup ecosystem, which is equally important as the past revolutionary changes in Rollup’s execution layer technology.
The size of the state usually grows in correlation with the speed of execution. When the performance of the blockchain is higher, the resulting state size tends to be larger, resulting in various decentralized networks claiming to have high execution efficiency, such as BNB Chain, Sei, and Base, all facing the problem of rapid state expansion.
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Changes in the state size of various blockchains
Why does Bitcoin have slower state growth? Aside from the lower network efficiency, it is because it uses the UTXO account model, and accounts without balances do not need to be recorded in the state, minimizing the problem of state growth. This makes the UTXO model relatively easier to manage but sacrifices programmability.
In contrast, Ethereum’s state model is a rich ecosystem composed of account balances, smart contract codes, and countless contract states. Due to the growth in network accounts, tokens, and contracts, the state of the network continues to increase rapidly.
In blockchain based on the account model, the state expands with each execution and transaction of smart contracts, leading to a bloated network, increased storage requirements, slower processing times, and inhibiting innovation and user adoption.
Therefore, most blockchains currently face the problem of state growth.
Possible solutions for state expansion
Although there is no clear solution mentioned above, developers have been discussing and proposing several strategies for managing state expansion in the future. However, many of these technologies are still in the theoretical or discussion stage, or have other drawbacks:
Allowing state development
Some people believe that accepting state growth in exchange for greater bandwidth usage is an option. However, Nick believes this is not a good choice because it would increase the hardware requirements for all nodes and reduce the decentralization of the network.
Charging users for storing state data to balance the problem of storing old data and excessive space usage. However, this approach needs to consider how to remove old data without affecting the storage of other data, as the state is recorded using a data tree, and the loss of intermediate data would break some branch paths.
Stateless design
Consider a design where full nodes do not need to store the state but rely on state proofs included in transactions and blocks. This essentially transfers the state from Layer1 to Rollups. Although this is the direction of Ethereum’s development (verkle tree), there are still many unresolved issues regarding its efficiency and maintainability.
Recommended reading:
Not Just Blockchain! How Stateless Infrastructure Brings Efficient Decentralized Networks
Reason for recommendation: In the case where state growth cannot be resolved, the “stateless infrastructure” that does not pursue consensus may have the opportunity to become a decentralized network that replaces the blockchain. This is also a topic that some developers are currently discussing.
A technology that manages state data in a different way. It uses full nodes to verify all contents or uses lightweight clients to sample transactions and completely discard the state tree.
Application-level state compression
Using call data technology to compress state data can be seen as trading bandwidth for state size. For example, compressed NFT (cNFT) on Solana stores the ownership proofs of NFT in a Merkle Tree. If you need to read it, you need to rely on the node’s bandwidth to call the data externally.
Compressed NFT stores ownership proofs in a Merkle Tree
(Source)
However, higher bandwidth requirements can limit the network and may affect the robustness and efficiency of the infrastructure.
Currently, the state size of Ethereum is approximately 267 GB, and it is growing at a rate of about 2 GB per month. If the number of network users and contracts increases in the future, this growth rate will be faster. The growth of the state will gradually become a burden for blockchain network nodes that need to pursue consensus.
Most of the existing solutions are still in the theoretical stage or have obvious shortcomings, and there is no clear consensus on the market. However, it is certain that the issue of state expansion is receiving more and more attention, and it can be expected that further solutions will emerge in the future. The latter part of the article also introduces innovative solutions proposed by Fuel Network, which will be explained in another article.
Fuel Network
Nick Didson
state
scalability
state expansion
Further Reading
Core Developer: Adjusting Block Space Size Requires Consideration of Multiple Factors, Gas Limit is not a Parameter to be Adjusted at Will
Vitalik Buterin: Scalability is One of the Biggest Challenges, Layer2 is the Future of Ethereum Scalability